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Occupational Noise Induced Hearing Loss and
Engineered Noise Control: Knowledge and Perception
in the Food Products Manufacturing Industry in
British Columbia
by
MUSARRAT NAHID
A THESIS SUBMITTED IN THE PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
Workplaces primarily rely on hearing protection devices (HPDs) for prevention of
occupational noise induced hearing loss (NIHL). This study was initiated to investigate the
potential barriers to the implementation of engineered noise control (ENC) which is considered
to be the best prevention measure. The study investigated knowledge and perception about NIHL
and ENC among decision-makers and workers in the food products manufacturing industry in
British Columbia.
We contacted company Health and Safety Departments. They were sent packages of
questionnaires and return envelopes for distribution among specified subjects. Follow-up phone
calls were made to increase participation. Analysis included descriptive statistics, non-
parametric methods and simple and multiple logistic regressions.
Twenty-two companies and 92 individuals participated (response rate 32.5%). Nearly
two-third of the respondents were non-management. A similar proportion was involved in health
and safety activities. The majority of the respondents perceived NIHL to be a big disadvantage
and said that they would be bothered by it. Respondents were knowledgeable about the effects of
noise exposure on health but had poor knowledge about harmful levels of noise, ENC and the
limitations of HPDs. They considered HPDs, hearing tests and education to be more effective in
preventing NIHL than ENC. Management showed poorer knowledge and lower perception than
non-management. Those involved in health and safety performed slightly better than those who
were not involved in such activities. Interventions should be undertaken to educate management
about ENC options and limitations of HPDs. Regulatory agency should create special branches
to help workplaces in choosing suitable ENC.
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Table of contents
Abstract .................................................................................................................................................................. ii
Table of contents ................................................................................................................................................... iii
List of tables .......................................................................................................................................................... vi
List of figures ...................................................................................................................................................... viii
List of abbreviations ............................................................................................................................................. ix
1.1 Occupational noise and hearing loss- the size of the problem ............................................................. 1 1.2 Noise induced hearing loss .................................................................................................................. 1 1.2.1Development of noise induced hearing loss ................................................................................ 1 1.2.2. The impacts of hearing loss on well-being ................................................................................ 2
1.3 Current interventions ........................................................................................................................... 3 1.4 Engineered noise controls .................................................................................................................... 4 1.4.1 Principles of engineered noise controls ...................................................................................... 4 1.4.2 Importance of engineered noise controls .................................................................................... 5
1.5 Current scenario regarding prevention of noise induced hearing loss ................................................................................................... 6
1.6 Research on barriers to the adoption of engineered noise control ..................................................................................................... 7 1.7 Importance of knowledge and perception ............................................................................................ 8 1.7.1 Knowledge of risk ....................................................................................................................... 8 1.7.2 Perception of risk ........................................................................................................................ 9 1.7.3 Knowledge of prevention measure ............................................................................................. 9 1.7.4 Perception of efficacy of prevention measure ........................................................................... 10 1.7.5 Importance of knowledge and perception in the context of health promotion model: the PRECEDE/PROCEED model ....................................................... 10 1.8 Research gap ...................................................................................................................................... 11 1.9 Study rationale ................................................................................................................................... 13
2. Research questions .......................................................................................................................................... 15
3.1 Ethics approval ................................................................................................................................ 16 3.2 Selection of companies ..................................................................................................................... 16 3.3 Study sample ..................................................................................................................................... 16 3.4 Recruitment and follow-up ............................................................................................................... 17 3.5 Questionnaire .................................................................................................................................... 18 3.5.1Questionnaire development ...................................................................................................... 18 3.5.2 Pretesting the questionnaire ..................................................................................................... 19
3.5.3 Questionnaire content ............................................................................................................. 20 3.5.4 Reliability of the questionnaire................................................................................................ 23 3.5.5 Delivery of the questionnaire .................................................................................................. 24 3.6 Data coding, error checking and management .................................................................................. 25
3.7 Data analysis ...................................................................................................................................... 27 3.7.1 Aggregate response .................................................................................................................. 27
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3.7.2 Response among subgroups ..................................................................................................... 27 3.7.3 Multivariable analyses ............................................................................................................. 28 3.7.3.1 Overview .................................................................................................................... 28 3.7.3.2 Knowledge of risk ...................................................................................................... 29 3.7.3.3 Perception of risk ....................................................................................................... 29 3.7.3.4 Perception of efficacy of engineered noise control .................................................... 30
5.1 Overview .......................................................................................................................................... 59 5.2 Answering the research questions .................................................................................................... 59 5.2.1 Knowledge of risk ................................................................................................................... 59
5.2.2 Perception of risk .................................................................................................................... 63 5.2.3 Knowledge of engineered noise control .................................................................................. 66 5.2.4 Perception of efficacy of engineered noise control .................................................................. 68
5.3 Recommendation .............................................................................................................................. 70 5.4 Future research ................................................................................................................................. 74 5.5 Strengths and limitations .................................................................................................................. 74
Appendices ........................................................................................................................................................... 86 A. Ethics approval ................................................................................................................................... 86 B. Invitation letter ................................................................................................................................... 87 C. Instruction sheet ................................................................................................................................. 89 D. Request for redistribution of the questionnaires ................................................................................. 90 E. Questionnaire ...................................................................................................................................... 92 F. Classification of questions ................................................................................................................ 112 G. Information letter .............................................................................................................................. 114
vi
List of tables
Table 1: Description of PRECEDE/PROCEED model ......................................................................................... 11 Table 2: Classification of questions based on contents ........................................................................................ 22 Table 3: List of subgroups .................................................................................................................................... 25 Table 4: Risk perception statements used for creating the dependent variable for MLR analyses of perception of risk ......................................................................... 30 Table 5: Demographical characteristics of the respondents .................................................................................. 33 Table 6: Characteristics of respondents in the subgroups (based on job responsibility and involvement in health and safety activities) ........................................................... 34 Table 7: Knowledge of risk (Likert scale questions) ............................................................................................ 36 Table 8: Knowledge of risk (multiple choice questions) ...................................................................................... 36 Table 9: Median and mode values of ranks for some occupational health problems ............................................ 39 Table10: Median and mode values of ranks for some chronic diseases ............................................................... 40 Table 11: Perception of risk among the respondents ........................................................................................... 41 Table 12: Knowledge of information sources of ENC ......................................................................................... 42 Table 13: Median and mode values of ratings assigned by the respondents to different prevention measures used to prevent NIHL ...................................................................................... 44 Table 14: Perception of feasibility and other benefits of ENC ............................................................................. 45 Table15: Percentage of respondents in the subgroups aware about the following facts about
noise exposure and hearing loss .................................................................................... 47
Table16: Percentage of respondents in the subgroups assigning “rank 1 (most concerning)” to hearing loss ................................................................... 49 Table 17: Percentage of respondents in the subgroups showing high risk perception regarding
the consequences of NIHL on life .................................................................................. 50 Table 18: Perception among subgroups (%) about a worker’s chance of developing NIHL and their own hearing ......................................................................................... 51
Table 19: Percentage of respondents in the subgroups aware of BC’s OHS regulations ...................................... 52 Table 20: Knowledge of information sources of ENC among respondents (%) in different subgroups .............. 52 Table 21: Percentage of respondents in the subgroups considering “ENC” as “highly effective” measure in preventing hearing loss ............................................................................. 53 Table 22: Results of simple logistic regression analyses between knowledge of risk and each independent variable
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(total number of respondents with good level of knowledge = 46) ........................... 55 Table 23: Results of MLR analyses of knowledge of risk .................................................................................... 55 Table 24: Results of simple logistic regression analyses between perception of risk and each independent variable (total number of respondents with high risk perception=74) ................................... 56 Table 25: Results of MLR analyses of perception of risk ..................................................................................... 57 Table 26: Results of simple logistic regression analyses between perception of efficacy of ENC and each independent variable (total number of respondents with high perception of efficacy of ENC=30) ........................................................................ 57
Table 27: Results of MLR analyses of perception of efficacy of ENC ................................................................. 58
viii
List of figures
Figure1: Ranks assigned by the respondents to some occupational health problems indicating how serious/concerning these were to them (with “1” being the most serious/concerning one and “5” being the least serious/concerning one) ....................................................... 38 Figure 2: Level of concern expressed by respondents if they were diagnosed with certain chronic diseases ........................................................................................... 40
Figure 3: Ratings assigned by respondents to different prevention measures in terms of their effectiveness in
noise control is not implemented ?” “implementation of noise control in workplaces”, “noise
control in workplaces”. Similar terms were used in Web of Science: “noise control AND
barriers”, “noise AND reduction AND workplace”, “noise control AND decision making” etc.
However, the literature search produced only a few relevant studies. A study (n=48 organizations
in the heavy and light engineering, 'high tech', agriculture, foundries, metal fabrication,
manufacturing, wool and textiles, oil and petrochemical industries, and local authorities in the
United Kingdom; method: audits of HCP, interviews and questionnaires), focused on the
individual and organizational factors affecting attitudes towards noise induced hearing loss
(NIHL), revealed some information on engineered noise control (33). This study reported that
the managers perceived ENC to be costly and complex. However, there was little evidence that
the managers thoroughly investigated noise control measures. They expressed the need for better
information on ENCs. Another study (n=4 workplaces: 2 sawmills and 2 machine shops in
Finland; method: workplace inspection and discussion with safety personnel and workers)
reported that a lack of knowledge of easy means to reduce noise was one of the reasons for not
implementing ENCs in workplaces (39); it suggested that the best way to promote a noise control
program was to give information and example of such programs. Thus, it is apparent that a lack
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of knowledge (information on ENCs) may be a barrier to the implementation of ENCs. An article
( based on the opinion of an individual researcher) on control of risks due to occupational noise
described step by step procedures for companies to minimize the risks of noise exposure to
workers (40); however it did not shed any light on barriers to the adoption of ENCs.
A pilot study (n=8 organizations in the food and beverage industry in BC; method: HCP audit,
interviews), focused on identifying barriers to the adoption of ENCs in workplaces (41),
identified several factors that may influence the decisions to implement ENCs in workplaces.
These were knowledge and perception of risk, expert knowledge (e.g. knowledge of prevention
measure, technical skill), corporate safety culture (e.g. avenue for worker participation in health
and safety, management’s preoccupations and priorities), socio-economic and cultural factors
(e.g. job insecurity which might prohibit workers’ from voicing concern), regulatory pressure
and technological context (e.g. enough information about noise emission on equipment to help
the management make informed decision while purchasing). This pilot study identified that
organizational decision making was a complex process in which numerous human and
organizational factors came into play. This study revealed that management taking action about
any hazard largely depended on workers identifying a problem and bringing it to the
management’s attention. The management then prioritized the hazards and made decisions.
However, the decision making largely depended on how noise was viewed by both the
management and workers and the management’s knowledge and perception about the efficacy of
control measures. Therefore, among all the probable barriers, the following human factors
appeared to have potential to influence the decision-making process regarding the
implementation of ENC in workplaces: 1) knowledge and perception of risk and; 2) knowledge
and perception of efficacy of prevention measure.
1.7 Importance of knowledge and perception
1.7.1 Knowledge of risk
A lack of knowledge is identified as one of the barriers to change (42). Knowledge about
occupational hazards is suggested to be a predictor of preventive behaviour at work (37)(43).
Providing knowledge about risk (such as, toxicity of lead) to workplace stakeholders (workers
(44)(45)and managers (45)) through educational intervention was found to be effective in
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reducing lead poisoning among workers. Other studies also reported similar findings. A review
published on a number of studies found that knowledge of AIDS, in general, was correlated with
AIDS-preventive behavior (46). It is suggested that knowledge of risk (means of AIDS
transmission) may be one of the necessary pre-requisites for risk-reduction behavior (46). In an
intervention study (47), designed to increase participants’ knowledge of risk regarding
cardiovascular diseases, it was found that knowledge of risk was associated with change in risk-
behaviour, which, in turn, resulted in physiologic changes in risk for cardiovascular diseases.
1.7.2 Perception of risk
Although knowledge is a necessary factor, it is not a sufficient reason to change
individual or collective behaviour. Motivation to change is dictated by a combination of factors
(48). Effective behavioural change is facilitated by greater knowledge, experience, and personal
risk perception (49). Risk perception plays a significant role as a predictor of workers’ protective
behaviour, such as, use of HPDs (50) (51)(34). A study on farmers’ use of protective equipment
regarding noise, sun, dust, pesticides, and tractors found that risk perception was strongly
associated with protective behaviour (52). Perceived risk of diseases (e.g. skin cancer) is a
motivating factor to change behaviour. Perceived severity and perceived vulnerability and
benefits are likely to motivate individuals to take preventive action (53). For example, people are
willing to pay more for products reducing the risk of skin cancer when they perceive a high level
of risk (54).These findings provide insights as NIHL is a chronic disease like skin cancer. Risk of
getting skin cancer could make people refrain from doing harmful activities such as sunbathing
(55).
1.7.3 Knowledge of prevention measures
It is suggested that risk-reduction behaviour is a result of the information people have about
prevention measures (46). This may well be true regarding the problem surrounding the adoption
of ENCs. Research suggest that a lack of information regarding easy methods of reducing noise
could hinder the realization of noise control programs in small and medium sized companies,
especially in small companies which may need the assistance of noise experts to plan and realize
a noise control program (39). Information and examples of noise control programs could
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encourage its uptake in workplaces (39). In one study involving a questionnaire survey of 48
organizations and detailed case studies of 10 organizations, it was found that the management of
most of the workplaces felt that information and practical guidance about ENC were inadequate
(33). Other studies also stressed the importance of knowledge of prevention measure. Two
studies on occupational lead exposure found that providing knowledge about prevention (how to
protect workers from lead exposure) to workplace stakeholders (workers (45) (44)and managers
(44)) induced behaviour changes among workers which reduced the risk of lead poisoning.
1.7.4 Perception of efficacy of prevention measures
Perception of efficacy of prevention measures may also be important. Perceived
ineffectiveness of the flu vaccine by health care workers was identified as one of the barriers to
its adoption (56). Perceived effectiveness of the flu vaccine is also considered to be one of the
reasons for its uptake by adults (57). One of the reasons behind choosing a particular birth
control measure by women was found to be perception of effectiveness of that measure (58).
Thus, perception of efficacy of a particular prevention measure may be an important factor to
influence people’s decision about adopting that measure.
1.7.5 Importance of knowledge and perception in the context of health
promotion model: the PRECEDE/PROCEED model
Health promotion has emerged as an important tool in combating leading causes of death
(48). Green’s PRECEDE/PROCEED model for health promotion planning has been proved to be
a successful model for health promotion in a wide variety of situations (48). It has also been
shown to be an effective tool in designing an occupational health and safety intervention1
(48)(59). The PRECEDE stage is the diagnostic or needs assessment stage and has 5 phases:
phases 6-9 belong to the PROCEED aspect of the model and deal with the implementation and
evaluation of the intervention (59). Table 1 summarizes the different phases of this model.
1 PRECEDE stands for predisposing reinforcing and enabling constructs for educational diagnosis and intervention; PROCEED stands for policy regulatory and organizational constructs in educational and environmental development
11
The PRECEDE framework helps the planner to shortlist potential factors out of a large
number factors that shape health status, as the target for intervention for improving health (48).
These factors are interrelated and can be categorized into three groups: predisposing, enabling
and reinforcing factors. As put by Green, “Any given behavior can be explained as a function of
the collective influence of these three types of factors.” Predisposing factors mainly belong to the
psychological realm and are defined as factors facilitating or impeding motivation to change.
These are knowledge, attitudes, beliefs, values and perceptions2 (48). Thus, from the above
discussion, it is apparent that knowledge and perception are important factors for improving
health conditions.
Table 1: Description of PRECEDE/PROCEED model
Phase Description
1. Social diagnosis Assessment of quality of life concerns of the community in question
2.Epidemiological diagnosis
Identification of specific health goals or problems that may contribute to the social goals or problems identified in phase 1. This is followed by a review of epidemiological and medical data, information generated through appropriate investigation. Moreover the size of the problem is also figured out to prioritize which health problem needs much attention
3. Behavioural and environmental diagnosis
Identification of the specific health related behavioural and environmental factors linked to the health problem/goal in phase 2
4. Educational and organizational diagnosis
Identification of a series of interdependent factors that influence the expected behavioural and environmental change selected in phase 3. These factors are called predisposing, reinforcing and enabling factors
5. Administrative and policy diagnosis
Assessment of organizational resources, policies and capabilities to support planned activities or interventions
6-9. Implementation and evaluation of the interventions
Implementation of the intervention, process evaluation, impact evaluation and outcome evaluation.
1.8 Research gap
Having described the occupational NIHL problem worldwide and the consequent
diminished quality of life experienced by workers (low self-esteem, difficulty in maintaining
2 Enabling factors are often conditions of living within the environment that facilitate the desired change and are
mainly created by societal forces or systems; examples being skills and resources. Reinforcing factors are the rewards or feedback received from others and social support after the change occurs
12
conversation and carrying out regular activities), other studies(16) (15) (17) have essentially shed
some light on phase 1 of the Precede/Proceed model. Phase 2 has also been investigated by other
studies which identified occupational NIHL as a contributor towards those concerns mentioned
above (16) (15) (17) and studies which defined the size of the problem (i.e. how many people are
affected) (1) (3) (4) (7) (8) (6). Environmental factors in the third phase are external to an
individual, which can be changed to facilitate the health or quality of life of the person affected.
Often these are beyond the control of the individuals-these factors may be organizational,
economic or factors in the physical environment. Phase 3 has also been investigated by other
studies (5) (41) which suggested reduction of noise through noise control solutions (i.e. ENC) as
a preventive action.
Workers’ health is not entirely dependent on workers themselves; workers seldom have
any voice in the decision to create a working environment where their hazards appear (60). It is
the firms that make major decisions about what to produce and how to produce it (60).
Availability and effectiveness of hazard control measures depend on employers (59). Other
researchers expressed similar opinions—much responsibility regarding occupational illness and
injury prevention lies on line and senior managers (61). Top management involvement in safety
was found to be associated with lower occupational accident rates (62). Thus, implementation of
ENCs in workplaces, suggested in phase 3, can only come through these people’s approval of
and support for ENCs. However, the role of joint health and safety committee (JHSC) members
is also critical in the prevention of occupational diseases and injury since they are responsible for
identifying occupational health and safety (OHS) problems and providing recommendations to
employers (63). Thus, both the management and JHSC can be considered as decision makers
regarding implementation of ENCs in workplaces.
However, to initiate and facilitate the maintenance of that behaviour (i.e. adoption of
ENCs) of the decision makers, the predisposing, enabling and reinforcing factors (of phase 4)
must be investigated. Then key factors should be sorted out to target interventions. There is an
order in how these 3 types of factors come into play to bring about a change in behaviour (48).
The first step is to facilitate the motivation to change; motivation is influenced by predisposing
factors. Then the deployment of enabling factors is needed to perform the required behaviour.
After the occurrence of the behaviour, it should be strengthened by the reinforcing factors. Thus,
13
it is apparent that, the first step regarding phase 4, should be to investigate the predisposing
factors such as knowledge and perception of decision makers.
A literature search was carried out in Pubmed, Web of Science and Google Scholar using
several combinations of the following keywords: risk perception/ knowledge, occupational
noise/NIHL, decision makers/ managers/health and safety committee. In the literature, there are a
few studies which reported findings on knowledge (64)(65) (34)and perception (34)(66,67) (24)
(68) of risk about NIHL. However, these studies involved only workers- not the decision makers.
Research involving decision makers and their knowledge and perception of efficacy regarding
ENCs is almost non-existent. A literature search using combinations of the following keywords
revealed no relevant studies: knowledge/perception of efficacy, noise control/ENC, decision
makers/ managers/health and safety committee. Only one study (33) reported management’s
perception about ENCs (cost and complexity); however, this study did not investigate
management’s knowledge and perception of efficacy of ENCs in preventing NIHL. Thus, there
is a need for research on 1) knowledge and perception of risk of NIHL and 2) knowledge and
perception of efficacy of ENC in preventing NIHL involving decision makers.
1.9 Study rationale
NIHL is a health problem that diminishes the quality of life of workers and hinders
their ability to work. Moreover, the number of NIHL claims is rising and consequently, the cost
of hearing loss claims will also rise. The best way to prevent NIHL is the elimination or,
reduction of noise in workplaces. Engineered noise controls (ENCs) hold the best promise in this
regard. According to noise regulations, the ENC option must be investigated as part of “Noise
control and Hearing Conservation Program”. However, this option is not followed by the
majority of workplaces whereas HPDs seem to dominate workplace-efforts in preventing NIHL.
After long-term existence of HCPs, both in the regulations and in workplaces, the situation still
has not improved. Thus, it is necessary to find out other ways to change this situation. Health
promotion principles, such as, Green’s PRECEDE/PROCEED model may offer an effective
solution to this problem since it has been found to be successful in dealing with a variety of
situations including occupational health problems. Important aspects in this concept are
knowledge and perception which are suggested to influence people’s motivation to change.
14
Research also suggested that knowledge and perception about risks (regarding NIHL) and
prevention measures (ENCs) were barriers to workplaces’ uptake of ENCs. According to
PRECEDE/PROCEED model, these factors should be the first foci of investigation when health
promotion approach is considered for a particular health problem. However, little research has
been done, in the context of NIHL prevention (through ENCs), to investigate the state of these
important factors among the workplace decision-makers. This study was initiated to partially fill
in this research gap. The research questions of this study are described in the next page.
15
2. Research questions
1. What is the level of knowledge and perception of risk regarding occupational noise exposure
and NIHL among decision makers and workers in workplaces? Do subgroups of respondents
differ in their knowledge and perception?
2. What is the level of knowledge among decision makers and workers in workplaces regarding
ENCs? What is their perception of ENCs’ efficacy to prevent NIHL?
Workers, in addition to decision makers, were included in this study since the pilot study
(41) revealed that change in the workplace was highly dependent on workers’ knowledge and
perception as well. The pilot study identified that the management relied on workers identifying
and reporting hazards and offering potential solutions to them.
“Knowledge of risk” was evaluated using questions about knowledge of the level of noise
that can damage hearing, temporary loss of hearing and tinnitus due to short duration of exposure
to noise, an early sign of NIHL, non-auditory effects of noise exposure, other causes of hearing
loss, and limitations of HPDs (tightness of fit, protection lost due to not wearing HPDs for the
entire shift); moreover, questions were also formulated to investigate the respondents’ awareness
about loud noise (whether it can damage hearing) and slow pace and insidious nature of NIHL
development.
“Risk perception” was evaluated using questions about respondents’ level of concern for
NIHL, perception of impacts of NIHL on life (difficulty in conversation, loss of quality of life;
whether they considered it a handicap, or a troublesome attribute; whether NIHL may be viewed
with contempt by others), and the chance of incurring NIHL at their workplaces.
With respect to “knowledge of ENC”, we were interested in knowing whether subjects
were aware of ENC (presence in the regulation), whether they were able to provide examples of
ENCs and knew where to find information on ENCs.
Regarding “perception of efficacy of ENC”, we were interested in knowing how
effective they thought ENCs were in preventing NIHL compared to other commonly used
prevention measures.
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3. Method
This study employed a questionnaire survey and statistical analysis (descriptive statistics,
non-parametric methods and multivariable analyses).
3.1 Ethics approval
All the requirements set out by the Behavioural Research Ethics Board (BREB) of UBC
were fulfilled. The approval letter is attached in Appendix A.
3.2 Selection of companies
The target sector was the food product manufacturing industry (WorkSafeBC industry
sector: manufacturing; sub-sector: food and beverage products; classification unit 711001 to
711022). This industry is identified as one of the high-risk categories for occupational NIHL
(69). WorkSafeBC’s statistics for 2005 show that 7.5% of all audiometric tests done within the
food products manufacturing industry indicated early warning change (EWC) resulting in a total
number of 329 EWC (70) cases-- a moderately high value among all the industries. Moreover,
the previously completed pilot study was focused on this industry. As this study was initiated in
response to the results reported by the pilot study, the same industry was selected for this study.
The study sample was mainly comprised of companies with HCPs. These were identified
from WorkSafeBC’s list of companies where workers went through audiometric tests. However,
a few of the companies in the sample were not from that list--they were recruited from the online
list of BC Manufacturers’ Directory (BCMD).
Although our target was to get all the companies with HCPs, it did not materialize
because of practical reasons. In order to recruit more companies, the BCMD list was used.
Companies from this list were chosen using convenience sampling.
3.3 Study sample
The target population of this study was those with decision-making and spending power
and workers. The potential study sample was expected to include JHSC members and some
people at workplaces who were not on JHSC. As JHSC comprises of people from both the
17
management and the non-management, we wanted to make sure that the non-JHSC group was
also comprised of both groups of people i.e. the management and the non-management. Thus, the
non-JHSC group was expected to be comprised of the following people: senior managers
(production/maintenance), senior financial officers, and workers (production).
3.4 Recruitment and follow up
The study population was recruited by the person responsible for health and safety (HS)
at each company. This person served as a contact person for a company for this study. BC
manufacturers’ directory and yellow pages were used to find out contact information of
companies. The contact person was contacted first by an invitation letter, then by telephone. The
invitation letter is attached in Appendix B. Upon his/her consent, this individual was asked to
distribute questionnaires in the company according to the instructions provided in the
questionnaire package. The instruction set is attached in Appendix C. The contact person was
asked to distribute questionnaires to all the members of JHSC and the following people: a senior
production manager who was not on that committee, a senior maintenance manager who was not
on that committee, a senior financial officer who was not on that committee and two production
workers who were not on that committee. The two workers in the non-JHSC group were asked to
be chosen based on their birthdays to ensure the randomness of selection —those workers whose
birthdays were closest to the day when the contact delivered the questionnaires. The researcher
did not have access to the contact information of the actual study participants. The contact
persons themselves were not asked to participate in this survey.
Repeated phone calls were made to reach the contact person. One major difficulty faced
by the researcher during recruitment was to get in touch with the contact persons in the
companies. As the company contact persons were high ranking officials (in charge of HS), in
most of the cases, the receptionists received calls and then transferred the researcher to the
contact person’s line or voice mailboxes. A Message (about the study, researcher identity and
contact information of the researcher) was left in the voice message box in each call with a
request to return the call. The reasons provided by the contacts for non-participation were that
they thought that people at their workplaces might not be interested in completing the survey or
they did not have time to fill out the survey. In a few cases they provided no explanation.
18
Follow-up phone calls were made to the contact persons approximately three weeks after
the mailing of questionnaires with a request to remind the participants to complete and return the
questionnaires. At the last phase, a few companies, who did not send any questionnaires back,
were sent another set of questionnaires with a request to distribute these to the same set of people
who were first approached. The letter with the request to redistribute the questionnaires is
attached in Appendix D.
3.5 Questionnaire
3.5.1 Development of the questionnaire
A literature search was carried by using combinations of the following keywords in
PubMed and Web of Science databases: knowledge/perception, noise, workplace/occupational,
step to find out what approaches (Likert scale, semantic differential scale, or multiple-choice
questions) work well (81). Several individuals (n=10) of a carpentry workshop were recruited.
After they had answered the questions in the questionnaire, a group discussion was arranged. The
focus group session moved from general to specific topics. Participants were asked whether they
had any difficulty in understanding the questions. In addition, they were also asked about their
overall thoughts on the questionnaire: whether it was interesting or not; whether the layout drew
their attention; how much time they needed to complete it; and any additional comments they
wished to make. Respondents were asked about clarity/ambiguity about some specific questions
which were identified by colleagues (who participated in the pre-test before the pilot test) as
unclear. The pilot test respondents were also asked how they had interpreted those questions. A
final version was then obtained after discussions and revisions by the research team and their
colleagues.
3.5.3 Questionnaire content
Items in the questionnaire were grouped in the following main categories:
Demographics;
Knowledge of risk;
Perception of risk;
Knowledge of ENC;
Perception of ENC
Other knowledge and perception
and “Audit”.
Audit questions in the questionnaire were used to gain some background information
about the companies, e.g. noise problem, efforts to prevent NIHL, the overall health and safety
situation, etc.
The majority of the questions were close-ended. Likert scale was applied where
appropriate. This scale is suitable for perceptions or attitude measurement (81). A self-developed
rating scale was used for 3 sets of questions on ENC and NIHL. Multiple choice questions and
checklist were also used. Use of open-ended questions was minimized.
21
The questionnaire for this study is attached in Appendix E. Table 2 provides a
classification of questions based on their contents. Moreover, detailed information about each
question and the classification group it belongs to is provided in another table in Appendix F.
22
Table 2: Classification of questions based on contents
Category Sub-categories Description
Knowledge of risk To test whether subjects are aware 1. that exposure to loud noise can damage hearing, 2. of harmful level of noise that can cause hearing loss (as specified in OHS noise regulations of BC), 3. that temporary loss of hearing and tinnitus (ringing in the ear) can occur with exposure to noise for some time, 4. that NIHL develops slowly, 5. that its progression is difficult to notice, 6. of an early sign of hearing loss, 7. of a few limitations of HPD: tightness of fit, protection lost due to not wearing HPD for the entire shift, 8. of some other effects of noise exposure apart from NIHL, and 9. of other causes of hearing loss ( ototoxic chemicals)
Perception of risk *To find out whether subjects perceive that 1. NIHL may be responsible for loss of quality of life 2. they will be bothered by NIHL had they developed it, 3. carrying out conversation may become difficult due to NIHL, and 4. Signs of NIHL may be viewed negatively (e.g. jokes or laughter) by colleagues *To find out how they would rate NIHL among other diseases or health effects in terms of seriousness or level of concern *To find out the respondents’ perception of a worker’s chance of incurring NIHL at their workplaces; to find out whether they felt that their own hearing was protected
Knowledge of ENC To find out 1. whether subjects can provide some examples of ENC 2. whether subjects are familiar with noise regulations (where requirements for ENC is set out) 3. subjects’ preferred sources of information for ENC
Perception of efficacy of ENC
To find out how subjects’ would rate ENC compared to other prevention measures in terms of its efficacy to prevent NIHL
Other perceptions about ENC
Perception of feasibility
To gain some idea about subjects’ perception of complexity associated with the implementation of ENC
Perception of cost as a barrier
To have some idea whether cost is perceived as an important factor regarding the implementation of ENC
Perception of other benefits
To find out whether subjects think that reduction of noise could improve their productivity and efficiency
Other 1.To have some idea about how much trust is put on audiometric tests (AT) 2.To test subjects’ perception of the effectiveness of hearing aids in treating NIHL 3.To know whether they liked a quieter workplace 4.To find out whether the respondents perceived that NIHL was preventable through HPD
23
Table 2: Classification of questions based on contents (contd.)
Category Sub-categories Description
e) Audit 1.Company effort to reduce noise
To find out whether any noise measurement and special training about noise is done in the company and whether there is any ENC in place.
2.Corporate culture To find out whether the company itself takes any initiative to prevent health hazards or, they don’t do anything unless workers complain.
f) Demographics
To gather background information about participants: duties in the current job, involvement in health and safety activities, education, gender, age and ethnicity.
3.5.4 Reliability of the questionnaire
To check for the reliability or internal consistency of the questionnaire, three pairs of
questions-with each pair bearing a different concept- were posed in the questionnaire. In other
words, both questions in a particular pair bore the same notion. The fact that respondents’
opinions are consistent across questions in a pair would indicate reliability. This approach of
reliability check was carried out by another study; it suggested that at least 3 pairs of questions
should be checked for consistency (82).
The questions are as follows:
Pair 1:
1. a) It is a big handicap to lose part of one’s hearing
1. b) If I developed hearing loss, I wouldn’t be bothered by it
Pair 2:
2. a) If a person is exposed to high level of noise for some time, his/her hearing could be
temporarily reduced.
2. b) Check all that apply:
Some effects of exposure to high level of noise for some time are:
* Slow reflexes
* Temporary reduction of hearing
* Pain inside head
* Permanent loss of hearing
* Tinnitus (ringing in the ear)
* Don’t know
Pair 3:
3. a) Hearing loss is preventable by wearing hearing protectors
24
3. b) Please indicate how effective it (each of the prevention measures: HPD, ENC, job rotation,
annual hearing test and education of employees) is in preventing hearing loss: Not at all
effective, somewhat effective, moderately effective and highly effective.
Both questions in pair 1 are Likert scale questions; however, both pair 2 and pair 3
contain questions of different designs—in each of those pairs, “a)” is a Likert scale question
whereas “b)” is either a multiple choice question or a rating question.
Cronbach’s alpha was also calculated for Pair 1. Cronbach's alpha is a useful statistic for
investigating the internal consistency of questionnaire answers (83)(84)(85). It is often used
when items in an instrument are not scored right versus wrong, for example, an instrument using
Likert scale (86) and items under the same construct. Cronbach's alpha will generally increase
when the correlations between the items increase.
3.5.5 Delivery of the questionnaire
A paper-based mail-out survey was chosen for this study. The questionnaire was
accompanied by a one-page cover letter explaining the purpose and the importance of the study
and assuring the participants of confidentiality and anonymity. The cover letter also included
details of the amount of time needed to fill out the questionnaire and contact information of the
researchers. A return envelope with paid postage was sent along with each questionnaire. In
addition to the instruction set for distributing the questionnaire, an information letter (Appendix
G) was sent to the contact person. The information letter was sent to thank the contact persons
for their help and also to refresh their memories about what the study was about. A package was
made up all these materials (information letter, questionnaires, return envelopes, instruction set)
and this package was mailed to the contact person.
As an incentive, study subjects were invited to participate in a raffle draw for an iPod
(CAD $200). The participants were asked to include their names and contact information on a
separate page. This page was severed from the questionnaire to ensure anonymity and was used
just for the purpose of the raffle draw. The University of British Columbia considers any raffle
draw a lottery if the draw does not include those who decline to participate. So, it was decided
that all the participants, including those who had not completed the questionnaire, would be
considered for the raffle draw. Only the winner was contacted
25
3.6 Data coding, error checking and management
Codes were assigned to individual companies. The questionnaire sent to a particular
company bore the corresponding code number. Within each company, each person was assigned
a code number to maintain confidentiality. A questionnaire ID was formulated combining both
the company code and the person codes. Each question in the questionnaire was given a distinct
code. Answer options in a particular question were assigned distinct numbers as codes.
First, data were entered in MS Excel by the researcher. Then a subset of questionnaires
(n=11) was checked for errors. Approximately 0.5 % of the data had errors. As the proportion of
error was very low, the accuracy of the original dataset seemed reliable. The dataset was
imported to STATA for analysis. In STATA, the data set was checked for out of range or
erroneous values. A few errors were found and corrected by the researcher.
Each demographical question in the questionnaire had a number of categories. Those
categories were combined into fewer subgroups. Table 3 provides a list of these subgroups. The
focus of the comparison, however, was subgroups based on job responsibility and involvement in
health and safety activities.
Table 3: List of subgroups
Characteristic Name of the subgroups
Job responsibility Management
Non-management
Involvement in health and safety activities Yes
No
Education Secondary or less
Post-secondary (non-degree)
Post-secondary (degree)
Age <=39 years
>=40 but<50 years
>=50 years
Ethnicity Caucasian from Canada
Other
Gender Male
Female
26
The groups are described below:
1. Responsibility in the current job:
� Management: This group was comprised of mostly managers; other type of jobs that were
included in this group were directors of finance, chief financial officer, and chief
engineer.
� Non-management: The remaining respondents were categorized as the “Non-
management”. This category included supervisors, foremen, technician, customer
service/sales, office administrative/accounting assistants, lead hands, drivers, machine
operators, warehouse, and others.
2. Involvement in health and safety activities: Two groups were created based on “involvement
in health and safety activities”: Yes and No.
� No: If a respondent chose “none” as an answer to the question “Have you been involved
in any of the following occupational health and safety activities over the last year ?”,
he/she was categorized as “No”
� Yes: The rest of the respondents were categorized as “Yes”.
3. Education: The 3 levels of education were created based on the researcher’s judgment.
Statistic Canada’s opinion about the variable containing information (which was gathered
through census) on a person's most advanced certificate, diploma or degree is as follows (87):
“There is an implied hierarchy in this variable (secondary school graduation, registered
apprenticeship and trades, college, university), … … …it is a general rather than an absolute
gradient measure of academic achievement.” Based on this, the following hierarchy in education
levels was assumed:
� Secondary education or less: some high school or high school graduate, Trade certificate,
midway through apprenticeship, Steam certificate and trade techno[logist].
� Post secondary education (non-degree): some college credit but no degree, college
The majority in the groups based on job responsibility and involvement in health safety
activities were from companies with HCPs (87% of the management, 84% of the non-
management, 81% of the group involved in health and safety activities, and 93% of the group not
involved in such activities).
35
4.6 Aggregate response
4.6.1 Knowledge of risk
Results on knowledge of risk are shown in Table 7 and Table 8. The respondents’
knowledge of risk was evaluated using questions in the area of effects of noise exposure on
hearing, a sign of hearing loss, development of hearing loss, the harmful level of noise exposure,
and limitations of HPD. Moreover, questions regarding knowledge of risk also included
knowledge of non-auditory effects of noise exposure and other causes of hearing loss apart from
noise exposure.
It appears that there was a high awareness among the respondents about the harmful
effect of noise exposure: damage to hearing capability (Table 7). Moreover, most of them were
aware about temporary effects of noise exposure on hearing (tinnitus i.e. ringing in the ear,
temporary loss of hearing) (Table 8) and an early sign of hearing loss (Table 8). There was also a
high awareness among the respondents about some facts about NIHL development: slow and
insidious nature of NIHL development (Table 7). However, there seemed to be widespread
ignorance among the respondents about the maximum noise level specified by the regulatory
agency- WorkSafeBC (Table 8).
Most of the respondents were aware of some non-auditory effects of noise exposure
(hypertension (Table 8), stress (Table 8), and annoyance (Table 7)). However, the majority
seemed to be unaware about other causes of hearing loss, for example, exposure to solvents
(Table 8).
The respondents were aware of the variability of the effectiveness of HPDs with tightness
of fit (Table 7). Although they appeared to know the importance of wearing HPDs throughout
the entire duration of noise exposure (Table 7), they did not have knowledge about the degree of
protection lost due to not wearing HPDs for only a short period of time (Table 8).
36
Table 7: Knowledge of risk (Likert scale questions)
Statement SD or D %
NAD %
SA or A %
DK %
n
Exposure to loud noise at work can hurt my hearing. 0 1 99 0 91
If a person is exposed to high levels of noise for some time, his/her hearing could be temporarily reduced.
7 1 92 0 89
The progression of hearing impairment is difficult to notice. 17 6 73 6 91
Hearing loss develops slowly with continuous noise exposure. 4 7 86 3 91
High levels of noise can cause annoyance at work. 0 4 96 0 90
Exposure to loud noise at a young age builds resistance to hearing loss. 80 2 10 8 91
If one really wants to keep one’s hearing, it is important for one to wear hearing protectors every time one is around loud noise.
1 6 93 0 91
Hearing protectors’ effectiveness could greatly vary with tightness of fit. 0 4 91 4 91 +SA: Strongly agree, A: Agree, NAD: Neither agree nor disagree, D:Disagree, SD: Strongly disagree, DK: Don’t
know, n: total number of respondents answering this particular question
Table 8: Knowledge of risk (multiple choice questions) Correct
Knowledge %
No Knowledge %
Wrong answer
n
According to BC regulations, the maximum level of noise that a worker can be exposed to for 8 hours (full shift) is 85 dBA
28 49 23 90
Some chemicals have shown to make ears more sensitive to noise. Tick all that you believe are related to hearing loss: Solvents (toluene, isocyanite)
15 75 10 92
Some effects of exposure to high level of noise for some time are: Temporary reduction of hearing, Tinnitus (ringing in the ear)
Tinnitus Temporary loss of hearing
76 67
7 8
18 25
92
An early sign of hearing loss is: Inability to hear high-pitched sound
68 19 13 91
Occupational noise can cause: Hypertension, Stress
Hypertension Stress
48 80
11 11
41 9
92
If you normally wear hearing protectors for a full 8-hour shift, how much protection do you think you will lose if you forgot to wear it 10% of the shift (30 minutes)?
Answer: 45-55%
6.5 40 53.5
37
4.6.2 Perception of risk
The respondents’ perception of risk was evaluated in different ways: level of concern for
hearing loss compared to other occupational health problems and chronic diseases and perception
of negative consequences of hearing loss on their lives. The results on risk perception are shown
in tables 9-11 and figures 1-2. Moreover, the respondents’ perception about the likelihood of a
worker’s chance of developing NIHL and perception about the safety of their own hearing were
also evaluated.
The respondents were asked to rank some occupational health problems to indicate how
serious or concerning these were to them. The health problems were as follows: hearing loss,
stress, chemical burns, repetitive strain injury (RSI), and accidents; the diseases were chosen on
the basis of number of claims accepted by WorkSafeBC for short term disability (STD), long
term disability (LTD) or survivor benefits for the year 2005 (93). Accidents were included as an
option because they resulted in several thousand claims in 2005 (94). A rank of 1 indicated
highest degree of concern and a rank of 5 indicated lowest degree of concern. Figure 1 shows
how the respondents assigned different ranks to these occupational health problems. While
comparing how the respondents assigned a rank of 1, it becomes clear that the proportion of
respondents who chose hearing loss as the most concerning health problem was lower than those
who selected accidents as the most concerning health problems. Moreover, while comparing the
median and mode ranks (Table 9), it appears that hearing loss received higher ranks compared to
both accidents and chemical burns; however, it received lower ranks compared to RSI and stress
(Table 9). These findings indicate that hearing loss was a matter of lower concern compared to
accidents and chemical burns but was of higher concern compared to stress and RSI among the
respondents.
38
Figure 1: Ranks assigned by respondents (%) to some occupational health problems
indicating how serious/concerning those were to them (with “1” being the most
serious/concerning one and “5” being the least serious/concerning one)
Table 9: Median and mode values of ranks for
some occupational health problems
Health effects Median rank
Mode rank
n
Chemical burns 2 2 89
Stress 4 5 90
Repetitive strain injury 4 4 89
Hearing loss 3 3 89
Accidents (e.g. struck by/against) 2 1 90
N.B. “1” being the most serious/concerning one
and “5” being the least serious/concerning one
39
The respondents were asked to indicate how worried they would feel if they were
diagnosed with the following chronic diseases: skin cancer, lung cancer, memory loss, hearing
loss, arthrhitis, and chronic depression. Figure 2 shows how the respondents assigned different
ratings (extremely, moderately, somewhat, or not at all worried) to different diseases. It is clear
that the proportion of respondents who assigned an “extremely worried” rating to hearing loss is
much lower than the proportions of respondents who assigned such a rating to lung cancer,
memory loss and skin cancer. The median and the mode values of ranks for hearing loss were
also lower than those of lung cancer, memory loss, and skin cancer (Table 10) (a larger rating
value indicates a higher level of concern). These findings indicate that hearing loss was
considered to be of lower level of concern by the respondents compared to those diseases.
However, hearing loss seemed to be of similar level of concern compared to chronic depression
and stress (medians and modes were the same for all these three conditions; in addition, the
proportions who assigned an “extremely worried” rating to these conditions were almost the
same except for stress).
40
Figure 2: Level of concern expressed by respondents if they were diagnosed with certain
chronic diseases
Table 10: Median and mode values of ranks for some chronic diseases
Diseases Median rank Mode rank n
Skin cancer 4 4 89
Lung cancer 4 4 89
Hearing loss 3 3 88
Memory loss 4 4 88
Arthritis 3 3 88
Chronic depression 3 3 88
N.B. Not at all Worried = rank1, Somewhat Worried = rank2, Moderately Worried = rank3, Extremely Worried = rank4
41
The respondents were asked to provide their opinion on the following risk perception
statements (Table 11). A response of strongly agree or agree indicates a high risk perception in
all the statements except statement 2 where a response of strongly disagree or disagree indicates
a high risk perception. Overall, the majority of the respondents showed high risk perception
about the impact of NIHL on quality of life. The majority perceived that hearing loss would be
an impediment to carrying out conversation with people and considered it to be a major
disadvantage. These findings are consistent with the fact that the majority opposed the idea that
they would not be bothered by hearing loss had they developed it. There seemed to be a mixed
opinion among the respondents about how a hearing loss victim would be treated by his/her
colleagues: a modest proportion of the respondents thought that signs of hearing loss may be
viewed with contempt by co-workers; a small fraction disagreed/strongly disagreed with this idea
and the rest remained neutral to this idea. The majority, in general, perceived noise to be a
significant cause of loss of quality of life.
Table 11: Perception of risk among the respondents
Risk perception statement SD or
D
%
NAD
%
SA or
A
%
DK
%
n
1. Losing part of my hearing would make it harder for people to talk to me.
2 1 97 0 91
2. If I developed hearing loss, I wouldn’t be bothered by it. 89 0 11 0 91
3. It is a big handicap to lose part of one’s hearing. 1 7 92 0 90
4. Signs of hearing loss are often met with jokes by co-workers/colleagues
20 33 43 4 91
5. Noise is a major contributor to loss of quality of life 2 7 90 1 90 +SA: Strongly agree, A: Agree, NAD: Neither agree nor disagree, D: Disagree, SD: Strongly disagree, DK: Don’t
know, n: total number of respondents answering this particular question
Greater than half (59%) of the respondents disagreed/strongly disagreed that a worker’s
chance of developing NIHL was low at their respective workplaces. The majority (81.5%), in
general, felt that their own hearing was protected.
42
4.6.3 Knowledge of engineered noise control
The respondents’ knowledge of ENCs was evaluated using an open-ended question
which asked them to provide examples of ENCs. In addition, the respondents’ awareness about
OHS regulations on noise was also evaluated. It was assumed that familiarity with noise
regulation might indicate the respondents’ awareness about ENCs and when to implement them.
Moreover, respondents’ knowledge about sources of information on ENCs was also investigated.
Only three respondents could provide “good” examples of ENCs (enclosure of workers,
equipment or foam insulation); very few respondents (n=3) had “some” knowledge of ENCs (use
of less reflective material on the wall, closing of noisy areas, insulation, loud printers and
machines in separate room from desk areas). Here, “good knowledge” implies respondents’
ability to provide concrete examples of ENCs (e.g., enclosure) and “some knowledge” implies
their ability to provide ideas (i.e. closing of noisy areas) which somewhat matches with the
principle of ENCs rather than exact examples of ENCs. However, many of the respondents
provided examples that can be categorized as administrative controls (purchasing of new
equipment, replacing the noisy one with a quieter one, good maintenance of equipment, job
rotation, moving the noisy machine where there are less workers, education of employees and
even changing jobs). Many of the respondents provided the same examples as provided by the
researchers at the beginning of “ENC” section in the questionnaire. A point to note here is that
out of 92 respondents, only 28 attempted to answer this question.
The majority of the respondents (65%) never read or saw OHS regulations of BC on
noise. The popular sources of information for ENC seemed to be Internet followed by workers’
compensation board, health and safety professionals, and JHSC respectively (Table 12).
Table 12: Knowledge of information sources of ENC
% of respondents
Internet 64
Workers Compensation Board 59
Health and safety professional 50
Joint health and safety committee 42
Acoustical consultants 27
Workers’ union 9
Other 3
43
4.6.4 Perception of efficacy of engineered noise control
The respondents’ perception of efficacy of ENC was evaluated using a question which
asked the respondents to assign ratings (highly, moderately, somewhat or not at all) to commonly
used prevention measures in terms of their effectiveness in preventing NIHL. The following
options were included in that question: HPD, ENC, education of employees, so that they can
protect themselves from noise exposure, annual hearing tests of employees, and job rotation.
Figure 3 shows how the respondents assigned different ratings to those measures. Going through
the “highly effective” ratings, it appears that the proportion of respondents assigning a “highly
effective” rating to ENC is lower than that of HPD, education, and hearing tests. Moreover, the
median and mode values for ENC were lower than those measures (except for hearing tests for
which the median value was the same as ENC) (Table 13). A larger rating value indicates a
higher level of perception. From these findings, it appears that the respondents had lower
perception of efficacy of ENC compared to HPD, education, and hearing tests. However, ENC
was thought to be more effective than job rotation by the respondents.
44
Figure 3: Ratings assigned by respondents to different prevention measures in terms of
their effectiveness in preventing NIHL
Table 13: Median and mode values of ratings assigned by the respondents to different
prevention measures used to prevent NIHL
Median Rank Mode Rank n
Hearing Protective Devices 4 4 89
Job rotation 2 2 89
Educating employees so that they can protect themselves from noise exposure
4 4 90
Engineered noise control 3 3 91
Annual hearing tests of employees 3 4 89
N.B. (1 = not at all effective, 2 = somewhat effective, 3 = moderately effective, 4 = highly effective)
45
4.6.5 Other perceptions about engineered noise control
Table 14 shows results on other perceptions about ENCs. ENCs were thought to be
beneficial to the improvement of workers’ productivity and efficiency by the majority of the
respondents. However, it appeared that there were mixed opinions among the respondents about
the complexity associated with ENC installation: a small fraction of the respondents thought that
installation of ENCs was difficult and complex; however, a similar proportion of the respondents
remained neutral to this idea and a similar proportion opposed this idea. Approximately half of
the respondents did not seem to have any opinion or know whether cost could be a major factor
in their decision to implement ENCs. However, a similar proportion was opposed to the idea that
they would not install ENCs because of its cost.
Table 14: Perception of feasibility and other benefits of ENC
Statement SD or D %
NAD %
SA or A %
DK %
n
Installing engineered noise control is complex and difficult. 33 15 34 18 91
I wouldn’t consider adoption of engineered noise control because it is expensive.
46 24 15 12 91
Reduction of noise to a comfortable level may improve workers’ productivity and efficiency.
According to BC regulations, the maximum level of noise that a worker can be exposed to for 8 hours (full shift) is 85 dBA
23 30 36* 10* 29 22 34 32 17 26 31 22 15 39
Knowledge about protection lost due to not wearing HPD just for 10% (30 minutes) of an 8-hour workshift
1 8 7 7 3 5 13 6 8 9 3 11 5 5
*p<0.05
48
4.7.2 Perception of risk
Table 16, 17 and 18 summarize results on perception of risk among subgroups. There was
no statistically significant difference among subgroups based on job responsibility and
involvement in health and safety activities in terms of level of concern for hearing loss (Table
16) and perception of negative consequences of hearing loss on their lives (Table 17). However,
more respondents in the non-management group showed high concern for NIHL than the non-
management. The majority in all those subgroups seem to perceive the negative consequences of
NIHL on life, however, the non-management and the group involved in HS activities seemed to
perceive the negative consequences more than their counterparts.
There was, again, no significant differences among these subgroups in terms of their
perception of a worker’s chance of developing hearing loss in their workplaces and their
perception regarding the safety of their own hearing (Table 18) except that the subgroups based
on involvement in health and safety activities differed significantly on their perception about the
safety of their own hearing. The proportion of those involved in such HS activities, who felt their
hearing was protected, was larger than their counterparts.
Other subgroups did not differ significantly on any perception question.
49
Table 16: Percentage of respondents in the subgroups assigning “rank 1 (most
concerning)” to hearing loss
Responsibilities
in the current job
Involvement in
health and
safety activities
Age (years) Gender Ethnicity Education level
Man
ager
ial
No
n-m
anag
eria
l
Yes
N
o
<=
39
>
=4
0 b
ut<
50
>=
50
mal
e
fem
ale
Cau
casi
an
fro
m
Can
ada
O
ther
s
S
PS
(n
on
-deg
ree)
PS
(deg
ree)
13 27 23 21 31 25 4 23 21 16 34 15 25 27
N.B. Mann-Whitney (for 2 group comparisons) and Kruskal-Wallis (for 3 group comparisons) tests were used to find out difference among subgroups in terms of ratings assigned to NIHL. These tests include all the different ratings (1-5) assigned to NIHL; however, in this table, proportions across subgroups are shown for “Rank 1=Most concerning” rating only just for simplicity
50
Table 17: Percentage of respondents in the subgroups showing high risk perception
regarding consequences of NIHL on life
Risk perception statement Responsibilities in the current job
Involvement in health and safety activities
Age (years) Gender Ethnicity Education level
Man
ager
ial
No
n-m
anag
eria
l
Yes
N
o
<=
39
>=
40
bu
t<5
0
>=
50
mal
e
fem
ale
Cau
casi
an
fro
m C
anad
a
O
ther
s
S
PS
(n
on
-deg
ree)
PS
(deg
ree)
Noise is a major contributor to loss of quality of life
93 93 94 79 93 92 91 91 96 91 82 92 93 87
Losing part of my hearing would make it harder for people to talk to me.
100 95 98 90 100 97 91 97 96 93 100 92 98 100
It is a big handicap to lose part of one’s hearing.
90 93 94 89 97 89 91 91 96 89 97 90 95 91
If I developed hearing loss, I wouldn’t be bothered by it
83 92 92 82 81 78 83 78 88 81 79 78 83 83
Signs of hearing loss are often met with jokes by coworkers/colleagues
33 48 44 39 45 38 48 42 46 46 39 42 49 35
“*” p<0.05
51
Table 18: Perception among subgroups (%) about a worker’s chance of developing NIHL
and their own hearing
Responsibilities in the current job
Involvement in health and safety activities
Age (years) Gender Ethnicity Education level
Man
ager
ial
No
n-m
anag
eria
l
Yes
N
o
<=
39
>
=4
0 b
ut<
50
>=
50
mal
e
fem
ale
Cau
casi
an
fro
m
Can
ada
O
ther
s
S
PS
(n
on
-deg
ree)
P
S(d
egre
e)
A worker’s chance of getting hearing loss is very low at this workplace (Strongly disagree or, disagree)
47 65 53 71 55 61 61 62 46 62 55 72 56 55
Do you feel that your hearing is protected? (yes)
90 77 92* 58* 72 83 91 74 83 83 79 78 85 82
*p<0.05
4.7.3 Knowledge of engineered noise control
The analysis on the major knowledge of ENC question (open-ended question asking for
examples of ENCs) did not seem reasonable as only very few respondents provided correct
answers. Table 19 and Table 20 show results on other knowledge of ENCs. There was no
statistically significant difference among subgroups in their knowledge of BC’s OHS regulations
on noise; however, the management and the respondents involved in HS activities were more
aware about these regulations than their respective counterparts (Table 19). There was no
statistically significant difference among groups in terms of their knowledge of information
sources of ENCs except the group based on ethnicity (Table 20).
52
Table 19: Percentage of respondents in the subgroups aware of BC’s OHS regulations
Responsibilities
in the current
job
Involvement
in
health and
safety
activities
Age (years) Gender Ethnicity Education
level
Man
ager
ial
No
n-m
anag
eria
l
Yes
N
o
<=
39
>
=4
0 b
ut<
50
>=
50
mal
e
fem
ale
Cau
casi
an
fro
m
Can
ada
O
ther
s
S
PS
(n
on
-deg
ree)
PS
(deg
ree)
Have you ever seen or read Occupational Health & Safety regulations of BC on noise? (yes)
38 30 40 24 29 35 44 40 21 35 36 35 36 35
Table 20: Knowledge of information sources of ENC among respondents (%) in different
subgroups
Responsibil
ities
in the
current job
Involvement
in
health and
safety
activities
Age (years) Gender Ethnicity Education
level
What sources would you use to access information about suitable ENC for your workplace? M
4.7.4 Perception of efficacy of engineered noise control
Table 21 shows results on perception of efficacy of ENC. There was no statistically
significant difference among any subgroups in their perception of efficacy of ENC in preventing
NIHL. However, going through the “highly effective ” ratings, it can be seen that more
respondents in the non-management group and in the group involved in HS activities considered
ENC to be highly effective than their respective counterparts.
Table 21: Percentage of respondents in the subgroups considering “ENC” as “highly
effective” measure in preventing hearing loss
Responsibilities
in the current job
Involvement in
health and
safety activities
Age (years) Gender Ethnicity Education level
Man
ager
ial
No
n-m
anag
eria
l
Yes
N
o
<=
39
>
=4
0 b
ut<
50
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N.B. Mann-Whitney (for 2 group comparisons) and Kruskal-Wallis (for 3 group comparisons) tests were used to find out difference among subgroups in terms of ratings assigned to ENC. These tests include all the different ratings (1-4) assigned to ENC; however, in this table, proportions across subgroups are shown for “highly effective” rating only just for simplicity.
4.7.5 Other findings
There was no statistically significant difference among the subgroups based on job
responsibility and involvement in HS activities regarding their perception about HPD. However,
the majority of the management (90%) and the group involved in HS activities (95%) believed
that NIHL was preventable through the use of HPD (results not shown).
54
4.8 Multivariable analyses
4.8.1 Association between independent variables
Only ethnicity and education were found to be significantly associated with each other
(p<0.01). Ethnicity was found to be a predictor of risk perception in a few studies (95) (96) (97).
So, it was initially included in the MLR model for risk perception; education was not considered
for this analysis. The same approach was taken for all the other MLR analyses.
4.8.2 Knowledge of risk
4.8.2.1 Univariate analyses
Results on the relationship between knowledge of risk and each independent variable are
shown in Table 22-odds ratio (OR) and 95% confidence intervals (95% CI) are provided. Two
independent variables were significantly associated with knowledge of risk- involvement in HS
activities and ethnicity. People involved in HS activities were more likely to have greater
knowledge of risk than those who were not involved in such activities (OR>1). Again,
Caucasians from Canada were more likely to be knowledgeable about risk than other people o
other ethnicity (OR>1).
55
Table 22: Results of simple logistic regression analyses between knowledge of risk and each
independent variable (total number of respondents with good level of knowledge = 46)
Since high-perceived risk could engender greater concern about a health hazard (53) and
as greater concern about a health problem (e.g., NIHL, skin cancer, and respiratory diseases) is a
motivational factor in taking preventive actions (54), the above result is meaningful. If the people
in the at-risk group consider that they are not at risk, the possibility of them being concerned for
themselves is low. If they do not feel concerned, they may not even have the motivation to report
the hazard to the appropriate authority in their workplaces.
Although this study did not carry out any on-site measurement of employees’ exposure to
noise, the noise levels in the majority of the companies may well be above the regulatory limit
since the majority of those companies have HCP (19 out of 22 companies) and HCP is required
when noise level exceeds the regulatory limit. However, only a small proportion of the
respondents in the decision making subgroups (the management and the group involved in HS
66
activities) appeared to perceive that their workers were at risk for NIHL (not all respondents in
these groups perceived this risk and only about half understood). If these groups do not think that
their workers are potentially at risk, it is less likely that they will be motivated to look for
prevention measures to put in place.
In conclusion, the respondents did not show high risk perception.
5.2.3 Knowledge about engineered noise control
Knowledge of ENC appeared to be very poor among the respondents. Overall, very few
respondents could cite concrete examples, could give ideas about ENC or were aware of OHS
regulations on noise which has a noise control component as the first priority. The decision-
making subgroups seemed to have poor knowledge about ENC since they showed poor
awareness about OHS regulations on noise (less than half were aware of OHS regulations).
Only a small proportion of the respondents would consider approaching acoustical
consultants to gain information about suitable ENC for their workplaces. Most popular sources
for information seem to be the internet and WorkSafeBC.
A review of literature revealed this to be the first study to particularly investigate
knowledge about ENC. Thus, it is difficult to conclude how our findings compare with existing
knowledge. However, a few studies revealed relevant findings that are concurrent with ours. The
pilot (41)study which was conducted in a similar sample revealed similar findings: weak
understanding of ENC among decision makers and also workers. The study in steel rolling mill
reported information on knowledge about prevention measure (66). It revealed that knowledge
about ENC among workers was poor (2% were aware of isolation of noisy machines as a
prevention measure) but knowledge of other prevention measures was better (98%, 55% were
aware about HPD, training of workers on hazards of noise). Moreover, a study (region:
Washington State in US) on NIHL in the workplaces (n=10) in an industry (foundry) with high
rates of NIHL claims revealed that no interviewed management representatives possessed a copy
of the regulations, or had read them (30).
Only a few respondents (n=3) answered the knowledge question correctly. The poor
response on the knowledge question may also point to another issue- whether the knowledge of
ENC question was well-designed in our questionnaire. The respondents might have skipped this
67
question because it was open ended; however, looking at the responses of another open-ended
question in this study (“what language do you speak at home?”), this does not appear to be the
case. One may again argue that use of unfamiliar terms such as “engineered noise control” might
have confused the respondents, but this term was explained at the beginning of the ENC section
in the questionnaire. Moreover, the pilot test provided no such indication of lack of clarity. The
large number of missing values, on the other hand, may just point to the overall state of poor
knowledge among the respondents—they might have skipped this question because they did not
have an answer.
The lack of knowledge about ENC among the respondents can also be partially verified
by the gathered data. It was found that the majority of the respondents used HPD and had their
hearing tested (slightly greater than half of the respondents used HPD and about nine-tenth of the
respondents had their hearing tested). Moreover, almost all said that NIHL was preventable
through HPD and that hearing tests gave advance warning of NIHL. In other words, there
appears to be high awareness about HPD and hearing tests. However, when asked whether there
was any ENC in their workplace, around half said that they did not know. This may point to a
lack of knowledge of ENC. However, a similar proportion said yes and a smaller proportion said
no. There were conflicting answers from the respondents within the same company and thus, we
cannot say for sure whether their answers are proof of their knowledge about ENC. Since the
respondents showed very poor awareness with OHS regulations on noise (which has a section on
noise control), it is likely that the awareness about ENC was poor among the respondents.
Moreover, the majority (two-third) of the respondents had a belief that ENC was complex and
difficult; but, in fact, ENC can be as simple as a thick carpet or a heavy curtain. A lack of
knowledge about ENC might have formed this notion.
OHS regulations on noise lay out all the steps including ENC necessary to prevent NIHL.
Since there was poor awareness about OHS regulation on noise among the group involved in HS
activities and the management (two-fifth of each group were aware), it is not unreasonable to
assume an incomplete implementation of HCP in the workplaces. This may be true since the
pilot study (41) (n=8 companies with HCP) revealed that HCPs were only partially implemented
in those companies. Moreover, the study in Washington State in an industry with high rates of
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NIHL claims revealed that all inspected companies (n=10) were out of compliance with hearing
conservation regulations (30).
Risk reduction behavior is supposed to be influenced by knowledge of prevention
measure (46,57). People need to know what prevention measures are available; if they are not
aware of a particular measure, it stands to reason that it will not be on their list of potential
choices. The poor awareness about ENC revealed by this study is, thus, a matter of concern. If
the management and those involved in HS activities are not aware of ENC, ENC may not even
be on their list of potential prevention measures. Moreover, people engaged in HS activities had
poor knowledge about ENC but they were pointed out as the preferred sources of information on
ENC. If these people are not knowledgeable, they obviously cannot guide the management or
other groups who seek advice on prevention measures, such as, ENC.
To sum up, we conclude that the knowledge of ENC was poor among the study
respondents.
5.2.4 Perception of efficacy of engineered noise control
The respondents’ perception of efficacy of ENC in preventing NIHL was very poor. They
considered it less effective than HPD, education of employees, and annual hearing tests. Both the
management and the group involved in HS activities had poor perception of efficacy of ENC
(only one-fifth of the management and two-fifth of the group involved in HS activities
considered ENC to be highly effective). After adjusting for the effects of age, gender, ethnicity,
education and involvement in HS activities, job responsibility was found to be associated with
perception of efficacy of ENC- the management was less likely to have high perception of
efficacy of ENC compared to the non-management. Involvement in HS activities was not,
however, associated with perception of efficacy after adjusting for age, gender, ethnicity,
education and job responsibility.
No previous study focused particularly on the perception of engineered noise control.
Only three studies revealed some information regarding ENC, but none of these investigated
respondents’ perception of efficacy regarding ENC (39) (33) (40). However, high perception of
effectiveness of HPD revealed in this study is concurrent with other studies. The pilot study
(41)reported that there was a belief that the hazard of noise was “adequately managed” by HPD
69
and hearing tests; HPD was described as a sufficient protection against noise and most of the
respondents thought it to be the best measure. The study on Swedish manufacturing workers (67)
and Michigan firefighters (24) revealed that the majority believed that NIHL was preventable
through HPD.
Perception of effectiveness of prevention measures plays an important role in people’s
decision about which to choose (57) (58). The findings of this study, therefore, are of
importance. If the management and the group involved in HS activities do not view ENC to be
highly effective in preventing NIHL, it may not be their highest priority while making decisions
about preventive actions against NIHL. Since the pilot study revealed that the management
wanted the workers to recommend potential solutions, it is important that workers also have high
perception about ENC’s effectiveness.
HPD was thought to be much more effective than ENC by the respondents although ENC
is considered to be the most effective measure to prevent NIHL by experts. ENC received even
lower rating (in terms of the perceived level of effectiveness) than education and audiometric
tests. The low rating of ENC may, partly, be a reflection of the respondents’ lack awareness of
ENC. If they do not know what ENC is, it stands to reason that they will not have high regards
for it.
Almost all (greater than or equal to 90%) of the management and HS respondents
believed that NIHL was preventable through HPD. It is possible that they might have a notion
that their workers were already protected from NIHL. Why would they consider searching for
other prevention measure when they believed that the current one was providing enough
protection?
In conclusion, the respondents had very low perception of efficacy of ENC.
The important findings emerging from this study are summarized below:
The respondents seemed to have a lack knowledge on important areas, such as,
limitations of HPD and harmful level of noise. There seemed to be a lack of understanding of
ENC among the respondents. The respondents considered it to be less effective than HPD,
hearing tests and education. In fact, HPDs seemed to be very highly regarded by the respondents.
70
With respect to subgroups, both the management and HS groups lacked knowledge about
important facts. Both of these groups had poor knowledge and perception of efficacy of ENC and
perceived that their workers might not be at risk for NIHL.
5.3 Recommendations
Health education is suggested to be an important tool in the prevention of occupational
diseases (45). Thus, an educational campaign should be undertaken to educate workplace
stakeholders about NIHL and ENC.
The campaign should focus on educating workplace stakeholders about ENC and its
effectiveness. They should also be made aware of the place of HPD in the hierarchy of control
measures. Moreover, they also need to be educated about the limitations of HPD and what
impact these limitations (tightness of fit and protection lost due to not wearing HPD for the entire
shift) have on the effectiveness of HPD. They should also be educated about the effectiveness of
hearing tests. The respondents in this study thought that audiometric test (AT) was a better
measure than ENC. Moreover, they believed that AT gave advance warning of hearing loss. But
researchers argue that these tests cannot detect hearing loss at an early stage (32).
Additional recommendations regarding educational campaign are that workplace
stakeholders should be informed about what level of noise is hazardous to hearing. Moreover,
they should be educated on how to subjectively judge the level of noise. This may be useful
when noise measuring equipment is not available right away. Training campaigns should also
focus on educating the workplace stakeholders about NIHL-how it develops and the importance
of taking precautions (since NIHL is irreversible and early signs are not easily noticeable, it is
important to take early actions). Particularly, the decision makers should be aware about how
NIHL can affect both the workers in respect to the loss of quality of life and the organization in
respect to financial loss due to accepted claims.
Since the study pointed out that the management had poor knowledge and perception
about ENC and poor knowledge and perception about risks regarding NIHL, this group should
be particularly targeted for educational campaigns. In another study, similar recommendations
were made “the need for more education and motivation of senior managers as the priority in
improving standards of hearing conservation and noise control” (33). Since management controls
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the resources, their knowledge and perceptions are utterly important. Other researchers also
implied similar opinion- education (44), training (103) (104) and support (44) (103)of the
management is important in maintaining health and safety at workplaces. The previous pilot
study indicated that the management depended on workers identifying hazards and offering
possible solutions and reporting those to them. It is unlikely that the management will trust
workers’ recommendation unless they understand the importance of prevention, are
knowledgeable about the best solution, and believe in its effectiveness.
Our study also pointed out the need for educating the group involved in health and safety,
since the results of this study indicated that the state of knowledge of risk and knowledge and
perception of ENC was also poor in this group. This group is partly responsible for workplace
health and safety. Moreover, HS professional and JHSC members were identified as two popular
sources of information regarding ENC and were considered to be responsible for identifying a
workplace hazard by the majority of the respondents. Thus, it is important that educational
intervention is directed towards this group as well.
Since the majority of the respondents chose Internet and WorkSafeBC as their sources of
information on ENC, policy makers should focus on developing online information sources and
special brochures on ENC and make them available through WorkSafeBC. These resources
should be designed, in such a way that it can provide easy to understand but thorough knowledge
of ENC, such as, what it is, how they work, benefits, price range, installation complexity,
consultants who can provide guidance on which ENC to implement, and stores that sell ENC.
Information on cost should be provided, as cost appears to be an important factor to the
respondents in making decisions about the implementation of ENC. Efforts should be taken to
make the HS people aware of these information sources so that they can learn about ENC and
provide guidance to those who seek advice regarding prevention measures. Easy access to
information may clear away subjects’ confusion about ENC. We recommend setting up of a
specialized branch within WorkSafeBC which will provide guidance and information on ENC to
those asking for help. A similar attempt was taken by WorkSafeBC a long while ago (Noise
Control Compliance Plan in 1980), but it was abandoned later. We recommend creation of a
similar branch.
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Since regulatory context was considered to be a barrier to the implementation of ENC in
the pilot study, we recommend a slight change in regulations: companies with noise levels
exceeding the permissible level should be required to contact the specialized branch of
WorkSafeBC. Moreover, WorkSafeBC should also offer educational workshop on ENC and
NIHL and require the attendance of JHSC members, health and safety personnel and the
management of such workplaces at these workshops.
It is our opinion that there should be a reward system for companies that implement ENC.
According to Green, a desired behavior will not sustain unless it is strengthened by
reinforcements, for example, rewards (48). According to us, the rewards for adopting ENC may
come in inexpensive ways. The regulatory agency or the government may hold a symposium to
confer awards, such as, certificates lauding these companies’ endeavors. This type of activities
carried out by the government or the regulatory agency will encourage other companies to adopt
ENC. In Singapore, the Ministry of Manpower, held such conferences and provided awards to
companies that controlled noise using ENC (26) and over the years, it was shown that more
companies implemented ENC. We suggest that the government considers making the cost of
ENC tax deductible or the regulatory agency considers reduction in the assessment rate for
companies implementing ENC.
Another way of promoting ENC will be to provide examples about what other companies
are doing- as suggested by another study (39). This may have great effects – if people see the
proof that ENC is effective, they are likely to be encouraged to adopt it.
Some other recommendations coming out of this study are briefly mentioned here:
One way to improve occupational health and safety situations in workplaces is by
enforcing laws by regulatory agency (105). A study in Oregon showed that increased regulatory
enforcement (e.g.safety inspections in areas known to be especially problematic, penalties
against employers that violated existing safety and health regulations ) along with government
initiatives to encourage management and labor to improve workplace safety resulted in a
decrease in NIHL claims rate- there was a 600% increase in the number of citations issued by the
regulatory agency against employers for safety violation after the enactment of law to augment
enforcement (106). Better enforcement is needed from WorkSafeBC. It should routinely visit
workplaces to check for records of noise measurement and implementation of other components
73
of HCP. As this study pointed out poor awareness among the decision-makers about OHS
regulations on noise, it is possible that they might be unaware about HCP, and thus, it is likely
that components of HCP, such as, noise measurement, may be missing. But, noise measurement
is an important step to identify whether the workers are at risk.
Moreover, WorkSafeBC should also make labeling of the noise level of machines
mandatory for companies that produce machines so that workplaces can make informed
decisions about choosing a low-noise machine.
More importantly, WorkSafeBC should change its impression about its focus regarding
NIHL prevention. We searched its web page on “NIHL Prevention” under the “Safety at Work
(by topic)”, but, looking at this page, it appears that WorkSafeBC’s focus is on HPD and
audiometric tests rather than ENC. This page contains information on various topics except
ENC. Information on HPD and AT seems more readily accessible than ENC, since these two are
shown on the first page. Information on ENC is located in a page that is far behind the other
pages. There is a lot of information on HPD (types of HPD, statistics on HPD usage by various
industry, working group, etc.) and audiometric tests (AT authorization, good booth, information
on records of these tests, etc.) but information on ENC seem to be smaller compared to AT and
HPD. All these may give a lay person an idea that WorkSafeBC gives more importance on HPD
and AT rather than on ENC. Thus, more online information should be provided on ENC, and this
should be made easily accessible. Moreover, during routine inspections, WorkSafeBC should
emphasize the need for implementation of ENC to the decision makers.
Above all, researchers should put their attention to the promotion of ENC. It appears that
HPD has been a topic of more extensive research compared to ENC. Research should guide
policy. In the absence of research on this topic, new and effective recommendations will not
emerge. The amount of HPD research done may give a lay person an idea that HPD is a very
important issue and that ENC is probably less important than HPD. If researchers are focused on
HPD, how can we expect to see a better picture among the lay persons, such as, workplace
stakeholders?
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5.4 Future research
It was not possible to know whether the companies had ENC or had high noise
levels. So, in future, a field investigation can be carried out to perform an inventory of ENC and
measurements of noise for such a study. The study can be replicated in a randomly selected
group of respondents with a revised questionnaire. The revised questionnaire may include
questions about the respondents’ idea of “loudness”. Respondents can be asked if they would
consider the presence of TTS or tinnitus to be concerning phenomena since some researchers
noted that TTS was not viewed as a matter of concern by people (34). If possible, an interview
method can be used rather than the questionnaire survey to have an in-depth understanding of the
respondents’ knowledge of ENC.
By identifying predisposing factors, this study partly completed the last phase of Precede
aspect of Green’s Precede/Proceed model. To make the phase 4 complete, the researcher
recommends future studies to investigate two other factors, namely enabling and reinforcing
factors, since behaviour is caused by the “collective influence of these three types of factors”
(48). After identifying all three types of factors, the next step should be to set priorities among
and within the categories and high priority factors should be targeted for intervention. This will
make the phase 4 complete. Then, the subsequent phases, phase 5 (assessment of organizational
resources, policies and capabilities to support recommendation) and phases 6-9 (implementation
and evaluations of interventions), should be carried out. After implementing the interventions in
a number of companies in the food products manufacturing industry, outcome should be
evaluated and the results should guide policymakers in formulating strategies regarding the
implementation of ENC and thereby preventing NIHL.
5.5 Strengths and limitations
The majority of the (n=78, 85%) respondents worked in companies with hearing
conservation programs; in other words-the majority of respondents belong to companies with
apparently high noise levels. Thus, the results may not be generalizable to the entire industry.
However, the responses of the study sample are still considered useful—the results of this study
may help formulate strategies to protect the workers potentially at risk of NIHL.
75
Since the respondents were chosen using convenience sampling, there may have been a
selection bias. The contact person might have given the questionnaires to those who were
interested in the survey, and thus, there may have been volunteer bias present. However, we
think that the results still provide useful insights. It is our assumption that people who are
conscious about health will be more interested to participate in a survey like this than those who
are not. Thus, we think that this study has captured the responses from health conscious group of
people. If this group has a poor state of knowledge and perception, it is likely that the responses
from those who are not conscious about heath would have been worse.
Response rate for individuals was 32.5 %. A scarcity of questionnaire survey research on
risk perception and knowledge on occupational noise and ENC and unavailability of response
rate data from such studies made it difficult for us to compare our response rate to that of other
studies. However, response rates for mail-out questionnaire surveys tend to be poor; without any
offer of incentive, the response rate may often be no more than 20%. Even with incentives and
follow-up phone calls, the response rates for such surveys can be quite low (107). The range of
response rates for mail-out questionnaire survey tends to fall between 10% to 50% (90).
Considering these, the response rate of this study can be considered good. The sample size (total
respondents) seemed moderate (n=92); one other study on knowledge and attitude on
occupational noise had a sample of 116 workers (66).
It is assumed that ENC is not in place in the participating companies and noise level is
high in these companies. As no field investigation was done, this assumption cannot be verified.
However, a study in the Washington State found that noise levels in workplaces in an industry
(foundry) with high rate of NIHL claims routinely exceeded 85 dBA (30) and that all workplaces
(n=10) were out of compliance with HCP. Moreover, none of those evaluated companies had
made any substantial past effort or future plans to reduce noise levels (30). Since the majority of
companies (86%) and the respondents (85%) of our study are from companies with HCP, those
above assumptions appear to be reasonable.
The study carried out a detailed investigation on perception and knowledge of noise risk
and ENC. It gathered data on a number of aspects of NIHL, ON and ENC. Moreover, it is unique
in the sense that according to our literature review, no other study focused particularly on
knowledge and perception on engineered noise control among decision makers.
76
The questionnaire used for this study seems to have fair reliability. It was developed and
reviewed by experts; so it seems to have construct validity.
77
6. Conclusions
The study reports perception and knowledge about occupational NIHL and ENC among
decision makers and workers in some food products manufacturing companies. Overall, it
appears that the respondents had very good perception of the negative consequences of NIHL on
life. However, they considered NIHL to be of lower concern compared to other health effects.
Respondents were knowledgeable about the effects of noise exposure on their health and also
aware of the insidious onset and slow developmental pace of NIHL. However, they had poor
knowledge about the harmful level of noise and the limitations of HPD. Respondents had poor
knowledge about ENC as well. There was very poor perception among them about the efficacy
of ENC to prevent NIHL. Compared to HPD, education of employees and annual hearing tests,
ENC was thought to be less effective by the respondents. Hearing protection devices were
thought to be the most effective measures. The management showed poorer knowledge and
lower perception in most cases compared to its counterpart. Most of the companies in the study
were from WorkSafeBC’s list of companies with hearing conservation programs, and as such, it
is not reasonable to make a generalization of the findings for the entire industry. As this study
appears to be the first of its kind, the results should be validated by further studies in future.
78
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Appendices
Appendix A: Ethics approval letter
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Appendix B: Invitation letter
School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address
Re: A study on noise at workplaces and engineered noise control
Dear Mr. < name >, We would like to invite your company to participate in a research study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. Your company was randomly chosen through BC Manufacturers’ Directory or Yellow Pages. Participation is simple. If you agree, we will send you a package of questionnaires, and ask you to distribute these to
• The members of your company’s joint health and safety committee
• A few other managers (preferably head of maintenance, head of production, financial officer) who are not on that committee
• Two production workers who are not on that committee.
The participants complete the questionnaire (it takes no more than 20 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire. There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative
88
impacts on the lives of the sufferers but also incurs huge financial loss to employers. Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain under-utilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. We hope you will help us in our effort to create a noise-free working environment .Looking forward to hearing from you soon. If you have any question, please email at [email protected], or call (604)827-4017. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia
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Appendix C: Instruction sheet
Instructions for distributing the questionnaires: Thank you for agreeing to participate in our survey. Please follow the instructions below
carefully:
• Please give one questionnaire to each of these following:
� All the members of your company’s joint health and safety committee � A senior production manager who is NOT on that committee � A senior maintenance manager who is NOT on that committee � A senior financial officer who is NOT on that committee � Two production workers who are NOT on that committee and selected as follows:
� To ensure a random selection, please select two workers whose birthdays
are closest to the date you deliver the questionnaire. If you have any questions about who to select, please call at (604)822-6777 or email at [email protected]
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Appendix D: Request for redistribution of the questionnaire
School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address
Re: A study on noise at workplaces and engineered noise control
Dear Mr. < name >, I am an M. Sc. student at the School of Environmental Health in the University of British Columbia (UBC). I contacted you some time ago about my thesis study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. You kindly offered your support for this study and I sent you a package of questionnaires after our discussion over the phone. I am hoping to get back as many questionnaires as possible to maximize the response rate which is very important for the successful completion of my thesis. For that reason, right now I am again sending questionnaires to the companies that I recruited. My aim is to reach out to those who probably couldn’t manage time to complete my questionnaires last time. I would greatly appreciate if you could distribute these questionnaires to the same persons you delivered the questionnaires last time but who did not have a chance to complete those. I hope this will allow them an opportunity to complete the questionnaires this time. Please note that the questionnaires must be given to the same persons. So contacting new persons is not necessary. Participation is simple. Please follow the Instructions for distributing the questionnaire attached with this letter. The participants complete the questionnaire (it takes no more than 15 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire.
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There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative impacts on the lives of the sufferers but also incurs huge financial loss to employers. Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain under-utilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. I greatly appreciate your kind support for this research. I hope you will help us in our effort to create a noise-free working environment. If you have any question, please email at [email protected], or call (604)827-4017. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia
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Appendix E: Questionnaire
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
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Appendix F: Classification of questions
Table: classification of questions into different categories Category Sub-category Question
number description
Risk perception 1,page5 Perception of the impacts of NIHL on life
5,page6 Perception of the impacts of NIHL on life
7,page6 Perception of the impacts of NIHL on life
10,page6 Perception of the impacts of NIHL on life
11,page6 Perception of the impacts of NIHL on life
1,page 9 perception of the level of concern for NIHL compared to other health effects
2,page 9 perception of the level of concern for NIHL compared to other diseases
9, page 6 perception of worker’s chance of NIHL
10,page 2 perception of own hearing
Knowledge of risk 1,page 8 knowledge of the level of noise that can cause damage to hearing
2, page 10 knowledge that temporary loss of hearing and tinnitus may occur with exposure to noise for some time
2, page 5 for reliability check---knowledge that temporary loss of hearing may occur with exposure to noise for some time
3, page 5 knowledge of some other effects (non-auditory) of noise exposure
6,page6 knowledge of risk of exposure to loud noise
1, page 10 knowledge of some other effects (non-auditory) of noise exposure
3, page 10 knowledge of other causes of hearing loss
12, page 6 knowledge that the progression of NIHL is difficult to notice
13,page7 knowledge of risk of exposure to loud noise
14, page7 knowledge that NIHL develops slowly
1, page 11 Knowledge of limitation of HPD
4, page 12 Knowledge of limitation of HPD
2, page 8 knowledge of an early sign of hearing loss
Knowledge of ENC open-ended Q, 14
what ENC is
1, page 15 knowledge of OHS noise regulation
2, page 15 knowledge of information sources
Perception of efficacy of ENC
1st Q, page13
perception of efficacy of ENC in preventing NIHL compared to other prevention measures
Other perceptions about ENC
perception of feasibility
1, page 13 perception of feasibility
perception of cost as barriers
2, page 14 perception of cost as a barrier
perception of other benefits
3, page 14 perception of other benefits
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Table: classification of questions into different categories (contd.) Category Sub-
category Question number
description
other 4, page 6 perception about audiometric testing
9, page 6 perception about the effectiveness of hearing aids in treating NIHL
3, page 12 Knowledge that HPD should be used continuously in noise
1, page12 Reliability check —effectiveness of HPD
Audit 9 of page 6, 1-4 of page16, 5 of page 17
background information about companies
Demographics 1-11 (except 10) of pages 18-20
personal characteristics of respondents
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Appendix G: Information letter
School of Environmental Health 3rd floor-2206 East Mall Vancouver, B.C. Canada V6T 1Z3 www.soeh.ubc.ca Tel: (604)822-9595 Date Name of the contact person Designation Company Address
Re: A study on noise at workplaces and engineered noise control
Dear Mr. < name >, Thank you very much for agreeing to participate in the research study on noise at workplace and engineered noise controls. Through this study, we are trying to understand how we can better reduce noise at workplaces. Your company was randomly chosen through BC Manufacturers’ Directory or Yellow Pages. Participation is simple. Please follow the Instructions for distributing the questionnaire attached with this letter.
The participants complete the questionnaire (it takes no more than 20 minutes) and then mail it back to us. A postage paid return envelope is attached to each questionnaire. There is no cost to the participant, and everyone who is asked to participate can have their name entered in a draw for an Apple iPod (value $300). However, providing names or contact information is optional. All the answers are kept confidential. Nobody will be able to identify any of the participants. The information provided will be grouped with other participants. Hearing loss caused from noise exposure at workplaces resulted in several hundred claims accepted by WorkSafeBC in the year 2006 alone. This not only causes significant negative impacts on the lives of the sufferers but also incurs huge financial loss to employers.
115
Research shows that reducing noise (i.e. using engineered noise control) shows the best promise to prevent hearing loss. However, in most workplaces engineered noise controls remain under-utilized, while the incidence of noise induced hearing loss remains high indicating the need for a new approach. This study is very important as it will help formulate strategies to create a safe and healthy working environment free of hazardous noise. We hope you will help us in our effort to create a noise-free working environment. If you have any question, please email at [email protected], or call (604)822-6777. Sincerely Musarrat Nahid, M.Sc. candidate, School of Environmental Health University of British Columbia