Evaluation of Airborne Hazards in the Workplace Flashcards by Ash Schafer

What is the difference between a grab sample and an integrated sample?

Grab sample - one time sample

Integrated sample - samples taken over a period of time (more usual since we compare to TWA)

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What is time weighted average

concentration of airborne hazard present during 8 hours

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Why are TWAs important?

Exposure may not be consistent throughout the day

Someone could be moving around, not near the hazard

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How have trends changed in terms of sampling devices?

Used to sample only, now sample and analyze

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What do sampling devices typically measure? what units?

concentration (how much dust per volume) in mg/ m3 or ug/ m3

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What is the difference between velocity and fowrate?

Velocity measures how fast air moves

Flowrate - volume that moves expressed over time (CFM)

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What is the equation for TWA?

(C1T1+C2T2+CnTn) / 8

C = concentration
T = time

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What should you refer to for proper sampling techniques?

NIOSH Manual of Analytical Methods (NMAM)

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What is the sampling “train”

Inlet –> collector and meter –> outlet

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Describe personal sampling

needs to be as close to the breathing zone as possible

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Which is better for determining the concentration that a worker is getting - air sample or personal sample

personal sample

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How does air sampling work?

place a monitor somewhere in room and it sits there

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What are considerations when sampling?

Is sample representative
how many samples?
who to sample
when to sample
efficiency
stability
safety
field ease

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Describe the set up of the filter cassette

specialized cassettes (collect a specific aerosol or dust, ie asbestos). Connected to tubing and a pump with medium flow rate sampling pump (2LPM)

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How do you determine the concentration of the substance with a filter?

Weight the filter before and after sampling

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What is the benefit of contour maps?

good for area samples

- look at highest concentrations in an area to establish the main sources

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Describe the direct reading aerosol samplers?

track dust - PM1, PM2.5, PM10, respirable, total PM size fractions

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What is PBZ?

Personal breathing zone

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What are cyclones used to measure?

Aerosol sizing

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What is the most common analysis for aerosols?

Gravimetric (weigh filter before and weigh filter after)

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What types of aerosol analysis can be used?

gravimetric
chemical analysis
Microscopy
Culture

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What would microscopic aerosol analysis be used to measure?

Asbestos, microorganisms

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What are some example of microbiological analysis?

PCR
Fluorescence
ELISA

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What should you test for in confined spaces?

Gas sampling

oxygen deficiency
% LEL
Specific gases (CO, O3, H2S)

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When should you sample confined spaces?

Before entering

What can charcoal tubes be used to sample?

vapors- like benzene

What equipment is used for aerosol sampling?

1) Personal Sampling Pump (medium flowrate) 2) Filter Cassettes 3) Cyclones (for aerosol sizing) 4) Direct Reading Aerosol Samplers (like the DustTrak)

How do you test for aerosols in ducts?

- Isokinetic sampling? | - Biosampler, like Anderson Biosampler

What equipment can be used for gas sampling?

- Sampling pump (low flowrate) - charcoal tubes- different tubes for different substance - direct reading instruments

What labs should be used for analysis?

Labs credentialed by the AIHA

What analysis is used for metals?

Atomic absorption

What analysis is used for organics?

Gas chromatography

What are the different types of lab analysis?

- atomic absorption - gas chromatography - electron microscopy - mass spectroscopy - Photometry

How can you calibrate a direct reading sampler

Zero gas or zero aerosol Known gas concentration

What way does the air move between the calibrator to the pump?

From calibrator, through filter cassette, to the pump or calibrator to cyclone to pump

Inhalable?

aerosols that can be inhaled (<100 um)

Respirable?

aerosols that can enter the pulmonary region (<10 um)

Thoracic?

aerosols that can enter the tracheobronchi region- <40 um

TWA

Time weighted average (concentration maximum averaged over 8 hours)

STEL

Short term exposure limit (concentration limit for 15 minutes)

REL

Recommended exposure limit- determined by NIOSH

PEL

Permissible exposure limit- legally binding by OSHA

TLV

Threshold limit value- ACGIH stanard

NMAM

Niosh manual for analytical methods

What are the parts of a sampling pump?

Inlet - pulls air in | Outlet - pushes air out

What mode are most pumps used in?

Suction mode

What pumps run on an alternating current and require an electrical outlet?

high flowrate pumps

What is the most common pump used in industrial hygiene?

Personal air sampling pump

What current do personal air sampling pumps run off of?

DC- direct current, use rechargeable batteries which take 8-16 hours to charge

Are personal sampling pumps safe to use in explosive environments?

Yes- totally enclosed and spark free

What is the most common medium and analysis for aerosol sampling?

Filters and gravimetric

How does gravimetric analysis of a filter work?

Weigh the filter before and after and the difference in weight is the weight of the aerosol. Net weight/ air volume gives the concentration.

What must be constant at both gravimetric weighings?

relative humidity

FIlters that are already weighed

matched weight filters

How does gravimetric analysis of pre-weighed filters work?

Measure difference in weight between used filter and blank filter directly from same box

What resource specifies the type of filter to use for each aerosol?

NMAM

What are the filters held in?

Filter cassettes

Why is there a backup filter in the filter cassette?

to prevent destruction by movement of air

How do you minimize sample lises?

Make sure the cassette is well sealed

What are the types of cassettes?

closed face- very small opening (minimizes loss of sample) | open face- large opening

Which cassette type is required for microbiological analysis?

open faced

What is the equation for flowrate?

Flowrate = volume/ time

What devices measure flowrate?

Flowrate meters

What are the simple/ more complext flowrate meters called?

primary- simple | secondary- more complex (only secondary if it holds a calibration well)

What is the concern with more complex flowmeters?

they do not hold calibration well

Describe the relatioship between the flowmeter and the pump

Some flowmeters built into the pump while others are put in the sampling train upstream from the pump

Describe the sampling train for a flowmeter

air enters --> collector --> flowrate meter --> pump --> air exits

Describe the calibration train

air enters calibrator --> collector --> flowrate meter --> pump --> air exits

How close a measurement is to the true value

accuracy

What is the calculation for % error. what does it help to measure

(Calibraory avg reading (LPM) - Device Avg reading) / calibratory avg reading * 100 Helps to measre accuracy

What is the calculation for estimate of accuracy?

100% - % error Need to calculate the % error first

indicates how close replicate values are to each other

precision

What equation is used to measure precision?

RSD- relative standard deviation

How do you determine from the RSD if the reading is precise?

The lower the RSD, the more precise the measurements

What is the equation for the RSD?

Standard Deviation/ mean

What is the difference between replicability and reproducibility?

replicability- within analyst' RSD (ie 4 students repeat the same measurement) Reproducibility- among laboratories' RSD

What is the TWA for: 8AM -10 AM : 3 mg/m3 10AM - 4PM : 2mg/ m3

((3mg / m3* 2 hrs) + (2 mg/ m3*6 hrs)) / 8 hrs= 2.25 mg/ m3

How do detector tubes/ charcoal tubes work? What type of analysis?

Have granules that absorb gas (use arrow to make sure air is moving the correct way) Connect tye to black filter side (sucks the air through) Break tips before- when done, cap Ship to the lab- analytical

Are you supposed to weigh the support pad with the filter?

What is the sample train between the filter and support pad?

Air is sucking so inlet --> filter pad --> support pad --> outlet

What is the purpose of the cyclones?

It removes all aerosols that are larger than respirable size

What calibration do you use for particle counters?

zero calibration

What is the particle counter that we have in the lab?

Dustrak

How can you prevent impact of relative humidity in gravimetric analysis?

Let the filters sit 24 hours before weighing before sampling and 1 hour after sampling

Evaluation of Airborne Hazards in the Workplace Flashcards

(84 cards)