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SECM/13/113
RISK ASSOCIATED WITH NOISE AND VIBRATION EXPOSURES AND THEIR
EFFECTS ON HEALTH OF WORKERS IN CONSTRUCTION SITES
V.H.P.Vithrana1, G.H.M.J. Subashi De Silva
2 and G.S.Y. De Silva
3
1Department of Civil & Environmental Engineering, University of Ruhuna, Sri Lanka
Telephone: +94 712767575; Fax: +94 912245762
E-mail: [email protected] ,[email protected]
2 and [email protected]
3
Abstract
Construction industry is one of main hazard industries, due to the nature of activities involved in
construction. In Sri Lanka, there are several research works investigating this hazardous nature based
on statistical data analysis of death and injuries caused by the risk factor having acute effect such as
working in higher places. However, no attention has been paid on health effects of construction
workers due the risk factors having chronic effects such as noise and vibration exposures. Objective
of this study is to investigate workers awareness on the risk associated with construction activities,
noise and vibration exposure levels in Civil Engineering Construction sites and the effects of noise
and vibration exposures on the health of workers. A questionnaire survey was conducted among
workers in building construction sites in the Southern Province, Sri Lanka. In addition, noise
exposure was measured by using noise level meter while vibration exposure was measured by using a
seat pad accelerometer attached to tri-axial vibration meter. The Relative Important Index (RII) was
determined to rank workers awareness on risk factors. RII values for “exposure to noise” and
“exposure to vibration” were 0.22 and 0.21, respectively. It was found that, although these two values
indicate that the workers are less aware about risk of noise and vibration exposures, exposing to
severe noise and vibration for a prolonged time can lead to adverse health effects. Noise and vibration
exposure levels prevailing in construction sites and their effects on the health of workers are
discussed in this paper.
Key words: Civil engineering construction sites, Construction worker, Noise, Vibration
1.0 Introduction
Construction workers do not generally have formal education such as college or degree acquired
skills, and belongs to lower strata of economy and privileges. There are many research on developing
new building technologies and economical factors on construction industry. Although the construction
worker, for the fruition of a project, does animportant work, there are no many research works
regarding construction workers. It has been reported that the construction workers are three times
more likely to be killed and twice as likely to be injured as workers in other occupations (Okela,
2009). This may be because of construction workers are at risk of exposure to various health hazards
that can result in injury, illnesses, disability or even death. Factors affecting this severe nature of
construction industry and possible methods to overcome them have been investigated recently (
Sawacha etal., 1999;Rameezdeen etal., 2003;Ismail et al., 2011;Ahamaed etal., 2011 ).
Sawacha et al., (1999) have investigated how historical factors (background and characteristics of the
individual such as age and experience), economic factors (monetary values which are associated with
Special Session on Construction Management, 4th International Conference on Structural Engineering and Construction Management 2013, Kandy, Sri Lanka, 13th, 14th& 15th December 2013
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safety such as hazard pay), psychological factors (safety behavior of fellow workers on site including
supervisors), technical and procedural factors (the provision of training and handling of safety
equipment on site) and the organizational and environmental factors (type of policy that management
adopts to site safety) are linked with the level of site safety. The study (Sawacha et al., 1999) has
analyzed the factors using accidents of 120 operatives in construction industry and found that the most
dominant factors influencing safety performance are organizational policies: management talk on
safety, provisions of safety booklets, provision of safety equipments, providing safety environment
and appointing a trained safety representative on site.
Rameezdeen et al., (2003) examined the accidents that were taken place at Sri Lankan construction
sites as recorded in the Industrial Safety Division (ISD) of the Ministry of Labour. The study also
certifies that age affects on construction safety, as workers over 60 years of age and less than 20 years
of age have been found to be over represented among fatalities. A survey conducted in Malaysia by
Ismail et al (2011) and a survey conducted in Sri Lanka by Ahamaed et al., (2011) found that the most
influential safety factor was personal awareness. In addition, Ahamaedet al, (2011) recommended to
provide a site plan for the safe access to the site, provide fences to keep the unauthorized persons
away, display warning signs at places to instruct workers to be cautions, declare proper walking and
vehicle paths to lead safe access to working place, keep the site tidy and clean, provide sufficient light
during dark in order to improve site safety.
A few research studies on fatal accidents and non-fatal accidents in Sri Lanka have been published
(Rameezdeen et al., 2003; Ahamaed et al., 2011). However, it is very hardly found a survey on
chronic effects from the risk factors such as noise and vibration exposures. Risk factors such as noise
and vibration exposures affect the worker, although the worker is less aware about these risk factors
than the other risk factors such as working in higher places. Eger et al., (2007) measured Whole Body
Vibration (WBV) exposure levels at the vehicle -seat interface and the operator- seat interface, during
the operation of both small and larger Load-Haul-Dump (LHD) vehicles. WBV levels have been
recorded during loading and unloading and mucking tasks of 16 different LHD vehicle models at
eight underground mining sites in Ontario and compared to the ISO 2631-1 health guidance caution
zones to determine safe exposure durations. Preliminary test results have indicated that LHD
operators were exposed to whole-body vibration levels putting them at risk for injury. ISO 2631-1
exposure guidelines for the health caution zone were exceeded during the operation of several
different vehicles. Although the situation in Sri Lanka might be the same as above, it is hardly found
any research on investigation about safety of construction workers exposed to severe vibration
exposures.
It seems that there are several noise sources in construction sectors and the noise levels are different in
each stage of a construction work. The report (Department of Environmental and Occupational Health
Science), which has been produced based on six years research in construction trades, stated that
repeated exposure to noise levels about 85 dB(A) (such as years of working around construction noise
without hearing protection) or from as little as one noise exposure above 140 dB(A) can damage
nerves in the inner ear, loosing permanent and irreversible hearing loss. Department of Environmental
and Occupational Health Sciencefurther stated that construction workers in Washington are more
likely to claimworkers’ compensation for hearing loss than that for workers in all occupations.
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Therefore, it is very important to investigate the workers awareness about the risk associated with
severe noise and vibration exposures in construction sites. In addition, it is necessary to have
quantitative estimation on possible exposure level of noise and vibration of construction workers in
Sri Lanka as it will be useful to make workers and contractors aware on possible health effects. The
relationship between the workers awareness about the risk factors and the exposing level of noise and
vibration is very important to minimize the bad health effects of construction worker. Objectives of
this study are to investigate the workers awareness about risk factors including the noise and vibration
exposure in Sri Lankan construction sites. In addition, a relationship between the noise and vibration
exposure levels and their bad health effects will be discussed.
2.0 Methodology
Workers’ awareness of risk factors wasinvestigated by conducting a questionnaire survey. Noise and
vibration exposure levels prevailing in construction sites and possible health effects were investigated
by measuring noise and vibration exposure levels in construction sites (i.e., objective responses) and
interviewing construction workers (i.e., subjective responses).
2.1 Workers’ awareness about risk factors in construction sites
A questionnaire survey form was developed for the workers in construction sites. Ten risk factors of
construction sites were identified using a literature survey and were considered in preparing the
survey form of worker. These risk factors were categorized into two, according to the time of
affecting them on the workers. Working in higher places, lifting heavy materials and electricity were
considered as risk factors having acute effects while dust, ionizing radiation and direct sunlight, hot
environments, vibratory tools, noisy environment and skin sanitizers were considered as risk factors
having chronic effects (Table 1). Each risk factor wasassessed by using three-point risk assessment
scale: high risk, medium risk and low or no risk.
Table 1: Categorization of risk factors
Risk factors
Chronic effects Acute effects
Dust Working in higher places
Ionizing radiation Lifting heavy materials
Direct sunlight Electricity
Hot environment
Vibratory tools
Noisy environment
Skin sanitizers’
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Construction sites in Galle and Matara districts were selected for this survey. The contractor of each
selected construction site is in grading M1. The survey was conducted within the period of three
months. The workers were interviewed for about ten minutes and the survey was performed in the
morning (i.e., between 9.00 am to 12.00 noon). Number of participants of the study is 100. The age of
workers, participated in the survey, is in the range between 18-67 years. Ninety percent of the workers
have studied only for G.C.E. (O/L) or less than that.
2.1.1 Relative Important Index (RII)
The Relative Important Index (RII) was determined to rank risk factors in an order of workers
awareness in particular risk factor.RII is given by Eq.(1);
(1)
where,w is the weighting assigned to each risk factor by the respondents, ranging from 1 to 5, and A is
the highest weight and N is the total number of samples. The RII was normalized as in Equation (1)so
that RII value will fall between 0 and1.
2.2 Noise and vibration exposure levels, and their effects on workers
A building construction site, in the Galle district, operated under a construction company having
grading M1 was selected. Foundation work was the major construction activity going on this building
site at the time when it was selected for measuring noise and vibration exposure levels.
Vibration exposure levels of Excavator operator and Soil Roller Compactor operator were measured
for a period of 30 minutes and 15 minutes, respectively. The excavator operator excavated the
construction site and the soil roller compactor operator leveled the ground of the construction site
when the measurements were recorded. Vibration exposure levels of the operators were measured at
the driver-seat interface during actual operating conditions according to the recommendations of the
International Standard ISO 2631-1997(International organization for standardization, 1997).Tri-axial
vibration meter and seat pad accelerometer were used to measure the vibration exposure level of
worker. The seat pad accelerometer was placed on the seat of the operators (Figure 1(a)) and it was
connected to tri-axial vibration meter (Figure 1(b)). Then, the operator was instructed to sit on the seat
pad accelerometer (Figure 1(c)).
In the tri-axial vibration meter, frequency weighting of Wd, Wk, and measurement range of 10 ms-2
were selected. As the worker is in seated position, frequency weighting,Wd, was used to weight the
vibration in X and Y directions. Frequency weighting, Wk., was used to weight the vibration in Z
direction. Figure 2 shows the basic centric axis (X,Y and Z axis) at seat back, seat surface and feet of
the human body in seated position.
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Figure 1: Procedure of measuring vibration exposure level of an operator (a) Seat pad
accelerometer on the seat of the operators, (b) Seat pad accelerometer with the tri-axial
vibration meter, (c) Operator sit on the seat pad accelerometer
Figure 2: Basic centric axes of the human body in seated position (ISO 2631-1, 1997)
Directional factors kx, ky and kz were set as 1.4, 1.4 and 1.0, respectively. Measured vibration
exposure levels were assessed by limit boundaries of vibration exposures as defined by the ISO -2631
(International organization for standardization, 1997) (Figure 3).
SL-1350(CUSTOM) sound level meter, which is capable in measuring noise in frequency range of
31.5 Hz to 8 kHz, was used to measure the noise level of construction sites and the noise exposure
level of operators. The sound level of the construction site was measured during two days for a period
of 20 minutes in randomly selected locations within daytime and was considered as an ambient noise.
During measuring the ambient noise level, an excavator, a soil roller compactor, an electric wood
cutter and an electric bar cutter were operated in the site.
Noise exposure level of Excavator operator, Soil Roller Compactor operator, Concrete mixing
operator, electric wood cutter operator and bar cutter operator was separately measured for twenty
minutes during the operation of their assigned tasks. “A” frequency weighting was selected in the
instrument to measure sound levels, as the human ear is less sensitive to low audio frequencies.
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Figure 3: Limit boundaries of vibration exposures as defined by the ISO -2631 (International
organization for standardization, 1997)
In practice, when measuring noise it is possible to take Leq (Equivalent Continuous Sound Pressure
Level)readings, with instrument, of short duration, i.e. <5 minutes, providing all variations of noise
emissions are covered.
Adding Leq values requires taking an anti-log of each value. The addition can be performed as shown
in Eq. (2) and the average noise level can be calculated. (Castle group, 2013)
10 Leq1/10
+10 Leq2/10
+10 Leq3/10
+…+10 Leqn/10
) / (2)
Here n is the total number of samples.
A questionnaire form was developed for the equipment operators in construction sites so as to record
subjective responses. Noise or vibration exposing hours per day, working experience and noise or
vibration related symptoms of the worker were found through the questionnaire survey. It was
recorded whether the workers have worn Personal Protective Equipments also.
3.0Results and discussion
3.1 Workers’ awareness about risk factors in construction sites
Figure 4 shows the Relative Important index (RII) of risk factors determined based on workers
responses. It verifies that the workers’ perceptions of the risk factors are poor as none of RII value of
risk factors percept by workers exceeded the limit 0.5. It has been identified that “working in higher
places” and “hot environment” are the most significant risk factors in construction sites: RII values
are 0.42 and 0.45, respectively.
The workers have the least awareness about risk of sever noise and vibration exposures. The RII value
corresponding to risk factors of noise and vibration are 0.22 and 0.21, respectively.The workers tend
to believe that when these vibratory tools are familiar for them, the risk is reduced. This is possibly
because they are mainly concern about acute effects due to injuries caused by vibratory tools.
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Although the noise of construction sites is generally high, workers have the same idea as for the effect
of vibratory tools: as these equipments are familiar with them there is no risk for the worker.
However, workers should be educated with the possible health effects of severe noise and vibration
exposure and most of health effects are irreversible.
Figure4: RII values of perception of workers
3.2 Noise and vibration exposure levels, and their effects on workers
Vibration exposure levels
Table 2(a) shows root mean square value, peak value,crest factor, vibration dose value, maximum
transient vibration value for X, Y and Z-axis.
It can be seen from Table 2(a) that for Soil Roller Compactor operator, the RMS value of vibration
exposures in Z-axis and X-axis exceeds 2.00 ms-2
. This magnitude of vibration (measured in RMS)
should be extremely uncomfortable for the worker (Mansfield, 2005). RMS value of X, Y and Z-axis
for both Excavator operator and the Soil Roller Operator exceeds the value 0.8 ms-2
. So that the
operators are in uncomfortable condition when they are operating the equipments (Mansfield, 2005).
However, operators judgment on “discomfort” would be highly subjective, as this may be mainly
depend on personal level of expectation.
0 0.05
0.1 0.15
0.2 0.25
0.3 0.35
0.4 0.45
0.5
RII
Val
ue
Perciption of the worker
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Table2 (a): Vibration exposures of the two operators
Op
erat
or
Ax
is o
f v
ibra
tion
Fre
qu
ency
-wei
gh
tin
g
Ro
ot
Mea
n S
quar
e
val
ue(
RM
S)
m/s
2
Pea
k v
alu
e
m/s
2
Cre
st f
acto
r
Vib
rati
on
Do
se V
alue
(VD
V)
m/s
1.7
5
(Max
imum
Tra
nsi
ent
Vib
rati
on
Val
ue
(MT
VV
)
m/s
2
Excavator
operator
X Wd(a) 1.24 20.00 16.13 20.00 4.83
Y Wd(a) 0.86 14.74 17.21 11.35 3.77
Z Wk(a) 0.61 7.19 11.88 13.28 3.95
Soil Roller
Compactor
operator
X Wd(a) 2.74 20.00 7.31 19.79 4.98
Y Wd(a) 1.19 18.45 15.45 10.58 4.25
Z Wk(a) 2.12 11.37 5.37 15.37 5.57
The RMS method of assessing vibration underestimates the effects of vibration with substantial peaks
(International organization for standardization, 1997).So that, it is recommended to use the crest
factor and it is defined as the ratio between the peak value and RMS value for the period of
measurement, T. For a more impulsive vibration, its crest factor is high. Health assessment based on
crest factor may be more appropriate for impulsive vibrations, because impulsive vibrations are
considered as more harmful than non-impulsive vibrations. The crest factor is often considered as a
good indicator of the harmful content of a vibration. It was found that the crest factor is greater than 9
for all the axis of Excavator operator. Vibration Dose Value (VDV) of each axis is greater than 9.1
ms-1.75
(exposure action value (Mansfield, 2005)). For the excavator operator, the crest factor of Y-axis
is greater than 9 and VDV value also exceeds the exposure action value of 9.1 ms-1.75
.
Mansfield (2005) explains .although there is a way to calculate MTVV; no guidance has been given
on how to interpret it. Therefore, the combined vibration value was calculated for each operator to
assess the vibration exposure based on the guidelines given in ISO 2631-1. Calculated combined
vibration value (av)for each operator is presented in Table 2(b). This value is also known as the
vibration total value of weighted RMS acceleration.
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Table 2(b): Calculated Combined Vibration Value for the two operators
Operator Excavator
operator
Soil Roller Compactor
operator
kx(directional factor for x axis) 1.4 1.4
ky(directional factor for y axis) 1.4 1.4
kz(directional factor for z axis) 1.0 1.0
Calculated combined vibration value
av[ (kxawx)2 + (ky awy)2 +(awz)2]1/2
m/s2(International organization for standardization,
1997)
2.20 4.69
Calculated Combined Value of Excavator operator and Soil Roller Compactor operator are 2.20 ms-2
and 4.96 ms-2
, respectively. Comparison of these values and limit boundaries of vibration exposures
as defined by the ISO -2631 (Figure 2), it can be identified that the both excavator operator and the
soil roller compactor operator are in caution zone according to the ISO 2631 guidelines if they are
exposed to 30 minutes and 15 minutes, only.
It was found that the daily exposure value for excavator operator is 0.55 ms-2
while the daily exposure
value for soil roller compactor operator is 0.8291 ms-2
. Both exposing level of excavator operator and
the soil roller operator exceed the daily exposure action value, which is 0.5ms-2
(European Agency for
Safety and health at work, 2008).
Noise exposure levels
The ambient noise level of the construction site was 71.17 dB (A), implying that the noise exposure
level of a general worker might not cause for any hearing loss, although it can be an annoyance to
workers (i.e., exceed the recommended level of environmental noise in commercial area, 65 dB (A))
(The Ministry of Transport, Environmental and Women’s Affairs; 1996).Noise exposure levels of
Electric wood cutter operators’ helper, Electric wood cutter operator, Electric bar cutter operator, Soil
Roller Compactor operator and Concrete mixture machine operator exceeded 85dB(A). This may
imply that all operators are at health risk due to severe noise exposures.
Noise exposing hours per day, working experience and whether they had wore earmuffs or not are
presented in Table 4. Any of the operators have not worn earmuffs. However, each worker exposes
higher level of noise (Table 3). These workers are exposing noise for a considerable period. As an
example Excavator Operator, Electric woodcutter operators’ helper, Electric woodcutter operator and
Soil Roller Compactor operator expose to noise for 8- 9 hours per day.
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Table 3: Noise exposure levels of operators
Equipment Operator Position of the sound level
meter Noise Level dB(A)
Excavator operator
0. 3 m away from the
operators’ ear
80.26
Electric wood cutter
operators’ helper 93.09
Electric wood cutter operator 101.5
Electric bar cutter operator 94.38
Roller operator 87.12
Concrete mixture machine
operator
1m away from the operators’
ear
At the side of
the engine
Other side
from the
engine
93.26 87.04
Table4: Working environment and the behaviour of the workers
Equipment Operator
Daily duration of
noise exposure (hr/
day)
Working Experience Wearing ear
muffs
Excavator Operator 8 8 years No
Electric wood cutter
operators’ helper 9 6 years No
Electric wood cutter
operator 9 3 years No
Electric bar cutter
operator 2-3 3 years No
Roller operator 8 6 years No
Concrete mixture machine
operator
The operator did not
provide the data
The worker did not provide
the data No
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Health effects
None of the operators did complain about hearing lose and about back pains (Table 5).
Table 5: Subjective responses about hearing lose and back pain
Equipment Operator Complains about Back pain Complains about hearing
lose
Excavator Operator No No
Electric wood cutter operators’ helper Not relevant No
Electric wood cutter operator Not relevant No
Electric bar cutter operator Not relevant No
Roller operator No No
Concrete mixture machine operator Not relevant No
According to Table 2(b), Calculated Combined Value of vibration exposures of Excavator operator
and Soil Roller Compactor operator are 2.20 ms-2
and 4.96 ms-2
, respectively. Comparison of these
values and limit boundaries of vibration exposures as defined by the ISO -2631 (Figure 2), it can be
identified that the excavator operator is in caution zone but Soil Roller Compactor operator might not
be in the caution zone , according to the ISO 2631 guidelines. Nevertheless both the Excavator
operator and the Soil Roller Compactor operator did not report any back pain (Table 4).
When vibration exposure levels exceed the limit boundaries, workers are at risk. Vibration induced
from construction machines may affect on major part of the worker’s body or only a particular organ
to vibrate. As a result, workers exposed to two different types of vibrations: segmental vibration and
whole- body vibration. When the Whole Body Vibration (WBV) energy enters the body through a
seat or a floor, it affects the entire body or a number of organs in the body (Griffin, 1996). Both
operators of excavators and soil roller compactors exposed to WBV mainly through the seats. The
symptoms of WBV are not so readily recognizable and are often mistaken for other unrelated
conditions. The health outcomes are non-specific and can be difficult to identify, manage and control.
Although the frequency of vibration exposures were not measured in the current study, the back of the
human body is especially sensitive to the vibration in the frequency range of 4-12 Hz then the spinal
column disease and complaints are most common. When the stomach exposes to frequencies between
4 and 5 Hz, digestive system diseases are often observed in persons. Prolonged exposure to WBV, at
frequencies below 20 Hz, caused for cardiovascular system problem. These result in hyperventilation
increased heart rate, oxygen intake, pulmonary ventilation and respiratory rate.The frequency of
vibration exposures of the operators, who work in construction sites, will be investigated in future
studies.
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As a general rule, workers are advised to used earmuffs whenever they are exposed to noise levels of
85dB (A) (Department of Environmental and Occupational Health Sciences; 2004). In this site, the
electric wood cutter operator, concrete mixture operator, concrete mixture operator, electric wood
cutter operator and soil roller compactor operators are exposed a noise level above 85 dB(A),
although they were not wearing earmuffs. Earmuffs can be used to control worker’s exposure to noisy
equipment and work areas.Exposing to 100 dB (A) for 1 hour is leading to hearing lose (Department
of Environmental and Occupational Health Sciences; 2004). However, the electric wood cutter has
been exposed to the noise level of 101.5 dB (A) for 9 hoursper day since 6 years and did not complain
about hearing lose, possibly because the worker has less awareness on health risk, often identifies as
annoyance or discomfort until permanent damage to hearing has occurred.
Permanent hearing loss is usually caused by long-term exposure to excessive noise. Excessive noise
causes to physical damage to the human hearing mechanism, which is incontrovertible (European
Agency for safety and health at work, 2005). This hearing impairment is known as Noise Induced
Hearing Lose (NIHL) that often progress slowly over many years and may go unnoticed until
permanent damage has occurred. The report (European Agency for safety and health at work, 2005)
further explains that excessive exposures to noise are probably the most common cause of hearing
loss due to damage of the inner ear. Prolonged exposure to sound level of more than 85dB (A) is
potentially hazardous although the important factor is total amount of exposure given by the level and
length of exposure time.
Noise can cause more harm than hearing loss, it can be a casual factor in work related stress, work
related voice disorders loss and can be a factor in work place accidents.
4.0 Conclusions
Most of the construction workers are not well educated although they are at risk of exposure to
various health hazards that can result in injury, illnesses, disability or even death. Although
construction workers make significant contribution to succeed engineering projects, less attention has
been paid for safety and health effects of the workers. .
In this study, site visits were made, questionnaire survey and interviews were conducted among 100
workers in construction sites to determine workers’ awareness of possible risk factors during their
construction tasks. Relative Importance Index (RII) was used to rank the possible risk factors. Noise
exposure level and vibration exposure level of construction workers were measured and their effects
on health risk were investigated through a questionnaire survey.
It was found that RII values for “Working in higher places” and “exposure to hot environment” were
0.42 and 0.45, respectively, implying that these two risk factorsare the most significant risk factors in
construction sites identified by workers. RII values for “exposure to noise” and “use of vibratory
tools” were 0.22 and 0.21, respectively, implying that workers were less aware about risk factors
having chronic effects.
Combined Vibration Value of Excavator operator and Soil Roller Compactor operator are 2.20 ms-2
and 4.96 ms-2
, respectively. Comparison of these values and limit boundaries of vibration exposures
as defined by the ISO -2631 standard, it can be identified that the both excavator operator and the soil
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roller compactor operator are in caution zone, although further investigations with many number of
operators are necessary. Construction workers who are operating electric woodcutter, electric bar
cutter, soil roller compactor operator and concrete mixture operator expose to a noise level greater
than 85dB(A) implying these operators are at risk, although any worker did not wore earmuffs.
Despite, being a well- known hazard, construction workers who are exposing to noise and vibration
are in risky. However prolonged exposure to vibration may cause cardiovascular system problem,
hand arm vibration syndrome while prolonged exposure to noise may cause Noise induced hearing
loss and even permanent hearing loss.
Acknowledgement
The study presented in this paper was conducted under the financial support received from
Transforming University of Ruhuna into International States (TURIS) project. The authors wish to
express their special thanks to TURIS for providing necessary funds to carry out this research work.
In addition, special thanks go to site engineers and the construction workers of the sites, which were
selected for this research, for their support and corporation.
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