1 Industrial hygiene exposure tt l assessment tools April 1, 2009 Session SCH316 Presented by Debbie Dietrich, CIH INDUSTRIAL HYGIENE EXPOSURE ASSESSMENT TOOLS www.skcinc.com AIR TESTING EQUIPMENT: SO MANY CHOICES THE FIRST STEP SURVEY TOOLS TO IDENTIFY CONTAMINANTS TO IDENTIFY CONTAMINANTS IN THE WORKPLACE
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Industrial hygiene exposure t t lassessment tools
April 1, 2009Session SCH316
Presented by Debbie Dietrich, CIH
INDUSTRIAL HYGIENEEXPOSURE ASSESSMENT
TOOLS
www.skcinc.com
AIR TESTING EQUIPMENT:SO MANY CHOICES THE FIRST STEP
SURVEY TOOLSTO IDENTIFY CONTAMINANTSTO IDENTIFY CONTAMINANTSIN THE WORKPLACE
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GENERAL CATEGORIESOF SURVEY TOOLS FROM SKC
Colorimetric Technologies
Sensor Technologies
Detector TubesColorimetric WipesColorimetric Swabs
CatalyticInfraredPhotoionizationElectrochemical Light-Scattering
SURVEY TOOLS USING COLORIMETRIC TECHNOLOGIES
DETECTOR TUBESA FIRST LINE OF DEFENSE
Classical measurement technique with first patent in 1919Glass tube containing a chemical media that reacts with the contaminant of interest by changing colorConcentration is read directly from a printed scale on the tubeTubes now available for measurement of over 200 gases/vapors
TYPES OF DETECTOR TUBESSHORT-TERM TUBES
Used with a hand-operated pump to collect on-the-spot measurementsMeasurements typically take a few minutes to completePump and tube are calibrated by the manufacturer as a unit
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NEW DEVELOPMENTOF SHORT-TERM TUBE TECHNOLOGY
CHIP MEASUREMENT SYSTEM (CMS)
Chemical-specific capillary p p ytubes using same technology as short-term tubes10 tubes on a chipUsed with an electronic analyzer with internal pump and data recorder
SKC 802-series
APPLICATIONSSHORT-TERM TUBES AND CHIPS
Qualitative AssessmentsLeak DetectionChemical Migration
Semi-quantitativeSpot checks of area or breathing zone samplesChemical Migration
Confined Space Entry (using extension hose)Unknown Identification(using HazMat kits)
breathing zone samplesMaximum levels during various processes or worker activitiesAnalysis of sample bags containing air emissions
TYPES OF DETECTOR TUBESLONG-TERM TUBES
Used with battery operated personal sampling pumps atsampling pumps at flows of 20 ml/minSample times range from 2 to 8 hours Off-gassing occurs during color change; protect the pump by using secondary trap tube
TYPES OF DETECTOR TUBESPASSIVE TUBES
Break open one end and place in designated holderSample from 1-8 hoursLength of stain indicates air concentration in ppm-hrDivide by hours sampled to obtain ppm concentrations in air
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APPLICATIONSLONG-TERM AND PASSIVE TUBES
Measurement of TWApersonal exposures
Long-term tubes availableAmmoniaCarbon DioxideCarbon DioxideCarbon MonoxideHydrocarbonsHydrogen SulfideNitrous fumes (NOx)Sulfur Dioxide
APPLICATIONSPASSIVE COLOR TUBES
Acetic AcidAmmoniaButadiene
Hydrocyanic AcidHydrogen SulfideNitrogen DioxideButadiene
Carbon DioxideCarbon MonoxideEthanolHydrochloric Acid
Nitrogen DioxidePerchloroethyleneSulfur DioxideTolueneTrichloroethylene
SOURCES OF ERRORDETECTOR TUBES
Accuracy is limited Interfering compounds cause similar reactions and readings on tubeAffected by temperature and humiditySubjective differences in “eyeballing” the color change to determine result
COLORIMETRIC WIPESFOR CHEMICALS ON SURFACES
Chemicals in air will eventually deposit on surfaces and may pose a risk to workers by skin absorption or ingestionskin absorption or ingestion. Chemical residue on shoes, lunch boxes, and other personal items may inadvertently become a take-home toxin for worker’s family members.
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FULL DISCLOSURE WIPESFOR LEAD ON SKIN OR SURFACES
Developed by US NIOSH; NIOSH Method 9105Licensed by SKCScientific breakthrough Colorimetric wipe for lead onScientific breakthrough- Colorimetric wipe for lead on skin or surfacesBehavior modification tool-Allows workers to determine if their hand washing has been thorough enoughLimit of ID is 18 ug of lead
LEAD WIPE KIT FROM SKC
Step 1 Step 2 Step 3
SKC 550-001
COLORIMETRIC SWYPES®
FOR SURFACE OR SKIN SCREENING
For use on surfaces:spray the developer solution, wipe with the Swype for the target compound, look for color change.For use on skin:Wipe skin with Swype, immerse in developer solution, and look for color change. SKC 769-series
COLORIMETRIC SWYPES®
APPLICATIONS
AminesIsocyanates
Assess engineering controlsDetermine effectiveness of
HydrazineAcid/Base
Determine effectiveness of cleaning and decontamination regimensMonitor non-controlled areas for contaminant migrationEvaluate gloves and PPE
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COLORIMETRIC SWABSFOR CHEMICALS ON SURFACES
Self-contained sampling swabs for rapid screening of specific contaminants Squeeze the swab to release the test reagents and then wipe the surface with the swabObserve color change
SKC 225-2404 series
COLORIMETRIC SWABSAPPLICATIONS
Lead-including lead in paint or lead dust on surfacesChromate-including hexavalent chromium dust on surfacesNickelMercuryCadmium
SOURCES OF ERRORCOLORIMETRIC WIPES AND SWABS
Cross-sensitivitiesExtremely heavy soiling or other contaminants on the test surface may interfere with color developmentPersons with color blindness may not be able to detect the color development.
SURVEY TOOLS USING SENSOR TECHNOLOGIES
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CATALYTIC SENSORSCOMBUSTIBLE GAS MONITORS
Commonly used since 1959Test gas or vapor is heated to combustion (burned) and the instrument translates the resulting increase in temperature/resistance as a percentage of the lower explosive limit (LEL).Oxygen (>10%) is required for the catalytic sensor to operate properly.
APPLICATIONSCATALYTIC SENSORS
Non-specific measurement of high, explosive concentrationsexplosive concentrations of gases/vapors in air:
Confined space entryEmergency response
Handheld 4-Gas Monitor including catalytic LEL sensor
SOURCES OF ERRORCATALYTIC SENSORS
Poisoning or degraded performance can occur when sensor is exposed to certain compounds such as lead containingcompounds such as lead-containing compounds, silicones, sulfur-containing compounds, and halogenated hydrocarbons.Oxygen deficient environments will cause the instrument to produce erroneous readings.
INFRARED SENSORSSTABLE AND RELIABLE DETECTORS
Infrared (IR) radiation of a specific wavelength is shined through a test gas or vapor and the amount of radiation absorbedvapor and the amount of radiation absorbed is proportional to the concentration of target compound.There are no requirements for a minimum level of oxygen like with catalytic sensors.
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APPLICATIONSINFRARED SENSORS
Combustible gasesCarbon dioxideRefrigerant gases (CFCs)
X-am 7000 monitor has choice of IR or catalytic LEL sensor
SOURCES OF ERRORINFRARED SENSORS
Will not detect non-hydrocarbon combustible gases such as hydrogen gas Condensing humidity can hurt performanceDust/dirt can coat the optics and impair response
PHOTOIONIZATION DETECTORSBROAD SPECTRUM VOC MONITORS
Based on the principle that some chemicals can be ionized when hit with high-energy UV light The instrument measures the resultinglight. The instrument measures the resulting current which is proportional to concentration of the gas/vapor in air. Instrument manufacturers publish technical documents with lists of chemicals that can be detected using UV lamps with various energy levels.
APPLICATIONSPHOTOIONIZATION DETECTORS
Non-specific measurement of ppm concentrationsconcentrations of gases/vapors in air:
Leak DetectionPersonal ExposuresSpill DelineationHazMat Response
www.raesystems.com
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SOURCES OF ERRORPHOTOIONIZATION DETECTORS
Non-specific-can not identify specific VOCDoes not detect all VOCs or compounds such as carbon monoxide, hydrogen, methane, oxygenHumidity can cause lamp fogging resulting in lower readingsSensor drift
ELECTROCHEMICAL SENSORSSPECIFIC TO TARGET COMPOUNDS
Contain components designed to react with a specific gas or vapor. The reaction generates a current which is translated intogenerates a current which is translated into concentration in air. Sensors available to measure about 20 compounds in the ppm range.Some cross-sensitivities can occur from other compounds.
APPLICATIONSELECTROCHEMICAL SENSORS
Measurement of ppm concentrations of target gases/vapors inof target gases/vapors inair:
Leak DetectionPersonal ExposuresConfined Space EntrySpill DelineationHazMat Response
4-gas monitor
Single-gas monitor
SOURCES OF ERRORELECTROCHEMICAL SENSORS
Cross-sensitivitiesSensor performance and lifetime can be affected by very dry or very humid environments or by brief exposures to high concentrations
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AEROSOL PHOTOMETERSMEASURE AIRBORNE DUST LEVELS
A light beam is shined through air containing particulate matter. The particulate matter scatters the light beam and the amount ofscatters the light beam and the amount of light scattering is measured on a photocell and displayed as mg/m3 concentrations. Commonly known as “light scattering” instruments
APPLICATIONSAEROSOL PHOTOMETERS
Screening tool evaluating personal dust levels SKC 770-seriesPerimeter samplingInternal dataloggers allow for TWA or peak determinationsInternal pumps allow for concurrent sample collection using filters
SOURCES OF ERRORAEROSOL PHOTOMETERS
Test dust does not produce the same results as the calibration dust; correction factor needs to be determinedneeds to be determinedDoes not respond to fibrous dusts like asbestos or to small ultrafine dustsAccuracy is not suitable for compliance purposes
CALIBRATION IS CRITICAL
All direct-reading instruments must becalibrated properly andcalibrated properly andregularly.
Both factory and usercalibrations are required.
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THE NEXT STEP
SAMPLE COLLECTIONUSING VALIDATED METHODS FORUSING VALIDATED METHODS FOR SAMPLING AND LAB ANALYSIS
VALIDATED SAMPLING AND ANALYTICAL METHODS
Published by government or other scientific agenciesDefine all the critical sampling parameters for accurately measuring exposures of specific chemicalsMost reliable means of evaluating exposures, but lab analysis takes time
COMMONLY USED SAMPLING AND ANALYTICAL METHODS
NIOSH Manual of Analytical Methodshttp://www.cdc.gov/niosh/nmam/
US OSHA Analytical Methods Manualhttp://www.osha.gov/dts/sltc/methods/toc.html
GENERAL CATEGORIESOF SAMPLING EQUIPMENT
Active Sampling for Gases/Vapors or
Passive Sampling for Gases/Vapors
ParticulatesPumpCollection MediaPump Calibrator
Badge with sorbentBadge with chemically treated filter paper
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AIR SAMPLE COLLECTION DEVICES
Active Sampling
ACTIVE SAMPLING
The collection of airborne contaminants by use of ani li Thair sampling pump. The
pump produces a forcedmovement of air to collectand/or concentrate thechemical of interest ontothe sampling media.
SAMPLING PUMPSTHE HEART OF ACTIVE SAMPLING
For most IH applications-GASES AND VAPORS are sampled at low flow rates to allow effective adsorption to occur onto the sorbent material.PARTICULATES are sampled at high flow rates so that airborne particles can be effectively trapped onto the filter material.
PUMP CALIBRATION
Set and verify the flowrate of the pump to that required in the qsampling methodShould be done before and after every sampleThe average of the pre- and post-flowrates is used in calculations of air volume
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TYPES OF CALIBRATORS
PRIMARY STANDARDS
SECONDARY STANDARDS
involve the direct measurement ofvolume on the basis ofthe physical dimensions of anenclosed space which do not change over time.
trace their calibration to primary standardsand have shown tomaintain theiraccuracy withreasonable handlingand care in operation.
PRIMARY STANDARDS
Film flowmeters or bubble burettesElectronic bubble metersElectronic “near frictionless” piston meters
SOAP FILM FLOWMETERS
Pump pulls air through a volumetric glass tubeTh li id b bbl i t d i t thThe liquid-a soap bubble-interposed into the flow pathThe air flow causes the film to move from one volume mark to anotherThe travel time is measured with a stopwatchBy knowing the travel time and the tube volume, the flow rate can be calculated
ELECTRONIC BUBBLE METERS
Work on the same principle as a manual film flowmeterInfrared sensors electronically time the bubbleInfrared sensors electronically time the bubbleMicroprocessor instantly calculates flow rate and displays it digitally
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NEAR-FRICTIONLESS PISTON METERS (DRYCAL TECHNOLOGY)
The flow of the pump causes the piston inside a chamber to rise and fall.Photo optic sensors sense the rise and fall ofPhoto-optic sensors sense the rise and fall of the piston.An electronic timer combine with a microprocessor to automatically measure traveltime and calculatethe flowrate.
SECONDARY STANDARDS
RotametersInternal flow sensorInternal flow sensor of an air sampling pump
COMMON MISTAKESIN PUMP CALIBRATION
Not calibrating pumps with a primary standard
Calibration should be done using a primarystandard or by aprimary standard
or a calibrated secondary standard
standard or by asecondary standardsuch as a rotameterthat traces itscalibration to a primary standard andis regularly recalibrated.
COMMON MISTAKESIN PUMP CALIBRATION
Using a rotameter at a different temperature and atmospheric
Rotameters are affected by atm pressure andtemperature Rotametersand atmospheric
pressure than those that existed during rotameter calibration using a primary standard
temperature. Rotametersshould be calibrated usingprimary standards under conditions of use ora mathematical correctionof the readings should bemade.
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COMMON MISTAKESIN PUMP CALIBRATION
Not calibratingwith the
Various types of samplingmedia produce pressure drops for which the pump
representative sampling mediain-line
drops for which the pumpmust compensate. For thisreason, it is recommendedthat pumps becalibrated to within +/-5%of the recommended flowrate with the media in-line.
PROPER CALIBRATIONENSURES ACCURACY
Air Volume Measurement of exposure level
Flow Rate X Time=Air VolumeMass of contaminant/Air Volume==
SAMPLING MEDIA FOR GASES AND VAPORS
SOLID SORBENTSINTRODUCTION
Most widely used media since 1973 Consist of small granulesConsist of small granules or beadsAdsorb the contaminant onto the surface Packed into tubes to collect various amounts and types of chemicals
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SAMPLE COLLECTIONWITH SORBENT TUBES
SOLID SORBENTSSPECIFIED IN SAMPLING METHODS
Trap and retain the contaminant even in the presence of other contaminantsAllow desorption of the contaminant Have sufficient capacity to retain enough contaminant for analysisDo not cause a chemical change of the contaminant
SOLID SORBENTSCOMMONLY USED TYPES
Activated Charcoal
Other CommonSorbent Materials
Most widely used solid sorbentHigh adsorptive capacity Derived from coconut shells
Silica GelTenax XAD-2Chromosorbs
SOLID SORBENTSSPECIALTY TYPES
SORBENTSSpecial Washings
APPLICATIONSInorganic Acid GasesAldehydes, Sulfur and
Special CoatingsBeaded SorbentsMicroporous SorbentsPolyurethane Foam (PUF)
Aldehydes, Sulfur and Nitrogen Dioxides, Methyl, Ethyl AlcoholFreons, Vinyl Chloride
Pesticides, Dioxins
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SOLID SORBENTSSPECIALTY TYPES
Sorbent/Filter Combination Tubes
Useful in evaluating contaminants in multiple phases or to scrub out interfering compoundsTubes available for collection of pesticides and hydrogen sulfide
SOLID SORBENTSSPECIALTY TYPES
Thermal Desorption Tubes
ApplicationsAmbient sampling of volatile organic
Use heat and a flow of inert gas to extract organic compounds from the sorbentNo dilution with solventMeasure sub-ppb levels
volatile organic compounds (VOCs)Indoor air studiesScreening for multiple compounds Low level personal sampling in the workplace
TUBES WITH SOLID SORBENTSADVANTAGES
Sample is integrated over the entire period of exposure.Published methods exist with extensivePublished methods exist with extensive testing and documentation of reliability.Workplace compliance officers typically use this sampling method. Air flow is calibrated and measured.Backup layer indicates sample breakthrough.
TUBES WITH SOLID SORBENTSADVANTAGES
Known contaminants can be quantified easily and economically using tubes with a single type of a specific sorbent.specific sorbent.Unknown contaminant mixtures can be identified and quantified using specialty thermal desorption tubes.Complex contaminants can be collected using sorbent/filter combination tubes.
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CHEMICALLY TREATED FILTERSINTRODUCTION
Filters are used as a substrate for liquid media that can trap contaminants.pLiquid media will chemically derivatizethe contaminant of interest.Result is a more stable compound for storage and analysis.
SAMPLE COLLECTIONWITH COATED FILTERS
TREATED FILTERSSPECIFIED IN SAMPLING METHODS
Serve as an alternative to wet chemistry methods using impingersEliminate storage instability problems encountered with some chemicals using sorbent tubes
TREATED FILTERSCOMMONLY USED TYPES
Chemical Treatment of
Applications
Glass Fiber Filters2,4 DNPH1-(2-pyridyl) piperazineSulfuric AcidMercuric Acetate
GlutaraldehydeDiisocyanates(HDI,MDI,TDI)Aromatic AminesMercaptans
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TREATED FILTERSADVANTAGES
Sample is integrated over the entire period of exposure.P bli h d th d i t ith t iPublished methods exist with extensive testing and documentation.Workplace compliance officers use these methods for some compounds.Air flow is calibrated and measured. Front and back filter can be used in one cassette to determine breakthrough.
SAMPLE BAGSINTRODUCTION
Used since the 1950’s to collect a fixed volume of an air-contaminant mixture intoair-contaminant mixture into a flexible container for subsequent analysisCalled “grab” samples in industrial hygiene and “whole air” samples in environmental field.
SAMPLE COLLECTIONWITH SAMPLE BAGS
Positive Pressure Negative Pressure
SAMPLE BAGSSPECIFIED IN SAMPLING METHODS
Benzene in NIOSH 3700
Nitrous Oxide by NIOSH 6000Sulfur hexafluorideCarbon Dioxide in
OSHA ID 172Carbon Monoxide in OSHA ID 210Ethylene Oxide in NIOSH 3702
Sulfur hexafluoride in NIOSH 6602Trichloroethylene in NIOSH 3701Various hydrocarbons in EPA 0040 and EPA SOPs
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SAMPLE BAGSAPPLICATIONS
Leaks, spills, emergency situations requiring rapid collection and analysis Peak concentrations from specific plant processes or worker tasksField applications using on site portable, direct-reading instrumentsGases or highly volatile compounds for which sorbent tubes are not available
SAMPLE BAGSADVANTAGES
Rapid analysis can be done in the field using direct-reading instruments.Economical as they can be reused a few times after cleaningInstantaneous concentrations can be determined.Collect “all” airborne contaminants
IMPINGERSINTRODUCTION
Impingers are specially designed glass bottlesthat are filled with athat are filled with acollection liquidspecified in the samplingand analytical method forthe collection of specificair contaminants.
NOTES ABOUT IMPINGERS
In some cases, the impingernozzle is fritted or modifiedwith thousands of smallholes. This dispersesthe air and allows for bettercontact between the airsample and the impingerliquid.
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SAMPLE COLLECTION WITH IMPINGERS
A sample pump is used tobubble air through theimpinger which contains aimpinger which contains aliquid reagent that has been specified in themethod. The liquid willphysically dissolve orchemically react with thechemical of interest.
SAMPLING MEDIA FOR PARTICULATES
PARTICULATESINTRODUCTION
Solid and liquid matter such as:Dusts-particles rendered airborne during crushing
i di f k lik t i lor grinding of rock-like materialFumes-airborne solid particles formed above molten metalMists-droplets rendered airborne by bubbling, boiling, spraying or splashingSmokes-particles resulting from incomplete combustion of organic matter
THE HAZARD POTENTIAL OF AIRBORNE PARTICULATES
Determined by:Chemical compositionpMass concentrationSize characteristics
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SIZE CHARACTERISTICS OF AIRBORNE PARTICULATES
Determine thedeposition site inthe respiratory tract. Smallerparticles will tendto deposit deep intothe gas exchangeregion of the lung.
SIZE-SELECTIVE EXPOSURE GUIDELINES
To more appropriately assess the possiblehealth effects of airborne particulate matter,exposure guidelines have been issued for different sizes of particles.
TRADITIONAL PARTICULATESIZE-SELECTIVE CRITERIA
Total Dust Respirable Dust
TOTAL DUSTINTRODUCTION
Dust that is captured onto a 37-mm filter loaded into a cassette and connected to a sampling p mp calibrated to a flo of at leastsampling pump calibrated to a flow of at least 1 L/min. The filter should be of a type and pore size appropriate to the particulate being sampled.Samples are collected in an area or in the breathing zone of workers.
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SAMPLE COLLECTIONFOR TOTAL DUST
RESPIRABLE DUSTINTRODUCTION
Is also collected onto a filter of a type and pore size that is appropriate for the particulate being sampled.Preceding the filter, however, is a particle size-selective device, typically a cyclone, that will separate the respirable fraction from the non-respirable fraction when connected to a pump sampling at the designated flow rate.
SAMPLE COLLECTIONFOR RESPIRABLE DUST
CYCLONESFOR RESPIRABLE DUST
Function on the sameprinciple as a
Large (non-respirable) particles hit the side of thecyclone and fall into the “gritcentrifuge. When
the air comes in through a small slit or opening on the sidea whirling action occurs within thestem of the cyclone.
cyclone and fall into the “gritpot” at the bottom of thecyclone and are discarded.Smaller respirableparticles are thrownupwards onto thefilter and are analyzed.
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CYCLONES LISTEDIN CURRENT NIOSH METHODS
Nylonat 1.7 L/min
Higgins-Dewellat 2.2 L/min
•SKC Aluminumat 2.5 L/min
SAMPLE COLLECTIONWITH CYCLONES
ALL CYCLONES ARE NOT CREATED EQUAL!
Each cyclone has different operating specificationsEach cyclone has different operating specifications and performance criteria. Be sure you know the flow rate specified to achieve the desired cut-point before using a cyclone. Be sure to leave the grit pot in place during sampling.
AIR SAMPLE COLLECTION DEVICES
Passive Sampling
PASSIVE SAMPLING
The collection of airborne gases and vapors ata rate controlled by a physical process such asdiffusion through a static air layer orpermeation through a membrane without theactive movement of air through an airsampling pump.
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PASSIVE SAMPLINGINTRODUCTION
Most passive samplers used in the workplace are based upon diffusionupon diffusion.
These devices rely upon themovement of contaminantmolecules across aconcentration gradient whichcan be defined by Fick’s FirstLaw of Diffusion.
IN OTHER WORDS...
Chemicals will diffusefrom an area of high concentration in theair to an area of low concentration on the sampler and the rate of diffusion forindividual chemicalshas be determined.
DETERMINATION OF SAMPLING OR UPTAKE RATES
Mathematical calculation based pon the theoretical
It is very important to know how thesampling rate wasupon the theoretical
diffusion coefficientMeasured sampling rate determined experimentally
sampling rate wasdetermined. This willgive insight intothe reliability of the sample.
DIFFUSIVE SAMPLERSSPECIFIED IN OSHA METHODS
Ethylene Oxide by OSHA 49 using 3M
Tetrachloroethylene and Trichloroethylene by OSHA 1001 i SKC
gInorganic Mercury by OSHA ID140 using SKCToluene by OSHA 111 using 3M or SKC
OSHA 1001 using SKCXylenes and ethyl-benzene by OSHA 1002 using SKCMEK and MIBK by OSHA 1004 using SKC or 3M
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DIFFUSIVE SAMPLERSSPECIFIED IN OSHA METHODS
Benzeneby OSHA 1005
FormaldehydeBy OSHA 1007 usingby OSHA 1005
using SKC 575-002 or 3M
SKC Umex 100,Assay Technology,or Supelco diffusivesamplers
DIFFUSIVE SAMPLERSTYPES AND APPLICATIONS
Solid SorbentNon-specific
Solid SorbentSpecific
DIFFUSIVE SAMPLERSTYPES AND APPLICATIONS
ChemicallyTreated Paper
DIFFUSIVE SAMPLERSADVANTAGES
Easy to useR i l t i iRequire less trainingEconomicalLess burdensome to workerShort and long-term sampling
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