Industrial Hygiene Air Sampling 101 (Basic) · 2019-04-11 · Industrial Hygiene Compliance 26 PUMP...

Your Solution for Environmental, Safety and

Industrial Hygiene Compliance

Industrial Hygiene Air Sampling 101 (Basic) Developed by: Daniel C. Maser, MS, CIH, CSP, ROH, FAIHA

President, Enviroair Consultants, Inc.

Development assistance from: Debbie Dietrich, CIH Vice-President, SKC



Before you begin an air sampling program....

It is important to determine your objectives before any sampling assessment.

Why is air sampling typically done? Lets discuss the reasons!!



REASONS TO DO AIR SAMPLING TO ENSURE COMPLIANCE WITH EMPLOYEE EXPOSURE STANDARDS

Including Both OSHA Regulations and ACGIH Standards



REASONS TO DO AIR SAMPLING

TO CHOOSE THE PROPER PERSONAL PROTECTIVE EQUIPMENT

• Historical databases on exposure levels will allow for selection of appropriate PPE for future tasks.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&docid=hH8rFr8IQjJTUM&tbnid=34xdvg2WBLiKHM:&ved=0CAUQjRw&url=http://www.dsei.com/site/index.php/services/industries/state-and-local-government&ei=bVFAU8uwJbTUsASn2YCIBA&bvm=bv.64125504,d.aWc&psig=AFQjCNHb9zIuCwNmRicYcHpgQt9O5tgmGw&ust=1396809899349952



REASONS TO DO AIR SAMPLING TO EVALUATE THE EFFECTIVENESS OF ENGINEERING CONTROLS

• OSHA requires employers to control exposures through engineering controls or work practices if feasible.

• Exposure reductions achieved from ventilation systems, or isolation barriers, other devices can be documented.



REASONS TO DO AIR SAMPLING TO EDUCATE WORKERS ABOUT THE IMPORTANCE OF SAFE WORK PRACTICES

• Air sampling results can be used to show workers the difference in exposure levels when safe work practices are used in their jobs.




TO DETERMINE THE SOURCE OF LEAKS • Direct-reading instruments can be used to

determine leak points around piping, pumps and other equipment.

• Some instruments have ultra-sensitive leak detection modes to determine “hot spots”.




TO AVOID FUTURE LITIGATION Chemical exposures that are within acceptable exposure levels and determined using validated, reliable sampling methods will reduce employers’ liability .



Now Determine How Your Chemicals of Interest Are Regulated

This will determine the type of sample you need to collect. There are three categories of exposure limits: 1. 8-hour time-weighted averages (TWAs) 2. Short-Term Exposure Limits (STELs) 3. Ceiling Values



8-Hour TWAs

All the high concentrations and low concentrations are averaged with respect to time.


Reflect the Average Full-Shift Exposure



8-Hour TWAs

where: C=Concentration of contaminant T= Incremental exposure time


Are Calculated as Follows:



STELs


Are defined as 15-minute average exposures which should not be exceeded at any time during a workday even if the 8-hour TWA is within acceptable levels.



Ceiling Values


Are concentrations that should not be exceeded during any part of the workday-- not even for an instant. Ceiling values are usually best determined with direct-reading instruments since tube & filters are normally require a 15 minute sample.



NOVEL WORK SHIFTS


OSHA and ACGIH use different approaches to calculating (extrapolating) exposures when employees work greater than 8 hour work shifts.



NOVEL WORK SHIFTS



NOVEL WORK SHIFTS The ACGIH uses the Brief & Scala Model to adjust the TWA-TLV. Generally you can use the following to adjust the TLV for extended work hours: Shift Length

(Hrs.) Brief & Scala

Method 8 1.00 9 0.83

10 0.70 11 0.59 12 0.50



CHOOSING AN AIR SAMPLING METHOD SAMPLING METHODS • National Institute for Occupational Safety and

Health (NIOSH) • Occupational Safety and Health Administration

(OSHA) • Environmental Protection Agency (EPA) • A qualified analytical laboratory can assist you in

choosing sampling methods most appropriate to the environment being sampled.



AIR SAMPLING METHOD • National Institute for Occupational Safety

and Health (NIOSH) http://www.cdc.gov/niosh/docs/2003-154/

http://www.cdc.gov/niosh/docs/2003-154/



AIR SAMPLING METHOD • Occupational Safety and Health

Administration (OSHA) https://www.osha.gov/dts/chemicalsampling/toc/chmn_T.html

https://www.osha.gov/dts/chemicalsampling/toc/chmn_T.html



20

ACTIVE SAMPLING DEFINED The collection of airborne

contaminants using a mechanical device such as a pump to draw the air/contaminant mixture into or through the sampling device such as a sorbent tube, filter, impinger, or sample bag.



21

THREE KEY COMPONENTS FOR ALL ACTIVE SAMPLING

• A sampling pump Something to pull or push air • A calibrator (flowmeter) Something to indicate how much air has been

pulled or pushed • The sampling media Something to pull or push the air through or

into for analysis



FIRST KEY COMPONENT: SAMPLING PUMP

22



23

CHOOSING A PUMP: FLOWRATE OPTIONS • GASES AND VAPORS are sampled on sorbent at low

flow rates (ml/min) to allow effective adsorption to occur onto the sorbent material. If impingers are used the flowrate is again normally less than 1 L/min. (What happens when sampling too fast with an impinge or bubbler?)

• PARTICULATES are sampled at higher flow rates (L/min) so that airborne particles can be effectively captured and drawn onto the filter material.



24

SAMPLING PUMPS: PERFORMANCE FEATURES

• Constant Flow-Is there an internal mechanism to compensate for restrictions to flow?

• Electromagnetic Susceptibility-Is there shielding from RFI/EMI?

• Backpressure-What is the maximum pressure drop that the pump can handle?

• Temperature and Pressure Correction – Most pumps do not do this!



SECOND KEY COMPONENT: CALIBRATOR (FLOWMETER)

25



26

PUMP CALIBRATION CLARIFICATION

• Done by the user to set and verify the flowrate of the pump to that required in the sampling method.

• Should be done before and after every sample.

• The average of the pre- and post- sample flowrates is used to calculate the air volume. Pre & Post should be within 5%!



HERE’S HOW THE PUMP CALIBRATION DATA IS USED

-The pump flow rate measured by your pump calibrator is multiplied by the total sampling time. Flow rate (L/min) X Time (min) = Air Volume (L) –This air volume is provided by you to the laboratory with your sample collection media. -The lab will then measure the amount of contaminant in mg or µg on the sample collection media and will use the air volume supplied to calculate concentration of the contaminant in air.

27



CALIBRATOR CLASSIFICATIONS: PRIMARY STANDARDS Historically, our profession has defined calibrators as PRIMARY STANDARDS if they involve the movement of a bubble or piston in a chamber of a known fixed volume.

28

EXAMPLES INCLUDE: • Soap bubble

meters/Film flowmeters • Electronic bubble

meters (Buck, Gilibrator) • Electronic piston meters

(Defender)



CALIBRATOR CLASSIFICATIONS: SECONDARY STANDARDS

• Calibrators that must be regularly calibrated to a primary standard are called SECONDARY STANDARDS.

• Rotameters are an example of a secondary standard.

29

If you use a 2nd Standard for Field Calibration – develop a calibration curve! • Affected by temperature and atm pressure



CALIBRATION SET-UP • Set up the pump and

sample media like its ready to place on the worker.

• Then attach the calibrator to the open end (inlet) of the sample media.

• Let your pumps run 5 minutes before calibration after removing them from the battery charger to let the flow stabilize.



31

FLOWRATE CALCULATION

Question: If it took 128 seconds for the bubble to travel a 500 ml volume, what is the flowrate? 500 ml X 60 sec = 234.4 ml/min 128 sec min



32

ELECTRONIC CALIBRATOR OPTIONS

• It is important to send pump calibrators used for critical flowrate measurements to an ISO 17025 calibration laboratory on annual basis for recertification to a national standard such as NIST.

• Users can then recalibrate their field devices (such as rotameters) themselves using their certified calibrator as the reference instrument.



TIP IN CALIBRATION SET-UP • If the sampler can not be

attached directly and it has no calibration adapter, use a calibration jar of a size to fit the sampler.

33



TRUE FIELD AIR VOLUME Lets review how not considering such issues can influence your results.

Assume you calibrate your pumps to 2 L/min at the office with a temperature of 750 F and a BP of 29.22” Hg, but the weather is changing and in the field the temperature is about 380 F and the BP changes to 30.22” Hg. Analytical results showed you had 23.50 µg of contaminant. What is the true exposure results!



TRUE FIELD RESULTS •

Does changes in Temp and ATM Pressure change our results – lets see!!



TRUE FIELD RESULTS

•


What was the STP field sample air volumes???



TRUE FIELD RESULTS

•

We need to get this back to Field conditions!!




TRUE FIELD AIR VOLUME •

So, if these were silica results from a construction project, would it matter? (OSHA Action Limit = 2.5 μg/m3)


Industrial Hygiene Compliance 39

SAMPLING MEDIA: ACTIVE SAMPLING OF GASES AND VAPORS



40

DEFINING GASES AND VAPORS • A substance is considered a GAS if this is its

normal physical state at room temp (25o C or 77o F) and one atm. (760 mm Hg or 29.92” Hg) pressure (Example: Carbon monoxide)

• If the substance is a liquid at normal temp and pressure, then the gaseous component in equilibrium with its liquid (or solid) state is called a VAPOR. (Example: Benzene or Mercury)



SOLID SORBENTS INTRODUCTION

• Most widely used sample media for gases/vapors

• Consist of small granules or beads • Adsorb the contaminant onto the

surface • Packed into tubes to collect various

amounts and types of chemicals for lab analysis

41 Not the same as colorimetric

detector tubes.



42

SAMPLE COLLECTION WITH SORBENT TUBES

Most tubes have 2 sorbent layers: • Larger section serves as the

primary collection layer • Smaller section is the back-

up layer The arrow on the tube indicates the direction of air flow.



MORE ON SORBENT LAYERS • Both sorbent layers are analyzed by the lab and

used to calculate exposure levels. • Breakthrough (sample loss) is indicated when

contaminant levels on the backup layer are ≥ 25% of the levels found on front sorbent layer.

• Samples are not valid when breakthrough occurs.

43



POSSIBLE CAUSES OF SAMPLE BREAKTHROUGH • High concentrations of target compound • High concentrations of similar compounds • High humidity

NOTE: When a high concentration is found on the backup layer, there is a concern that some chemicals escaped completely from the tube.

44



SORBENT TUBES FOR PPM LEVEL MEASURMENTS • After sampling, you will seal the glass tubes with

caps provided, label the tube, and send to the lab.

• The lab will break open the tube, pour the

sorbent into vials, add a liquid solvent, and shake for a while so that the solvent extracts the contaminant from the solid adsorbent and into the liquid for GC analysis.

45



46

SPECIALTY OVS SORBENT TUBES Sorbent/Filter

Combinations- Specified in OSHA and NIOSH methods for pesticides:

Internal filter captures aerosol phase of the contaminant.

Sorbent material collects vapor phase of the contaminant.



47

TYPES OF SORBENT MATERIAL: CARBON BASED SORBENTS

• Activated charcoal-Most widely used solid sorbent suitable for collection of non-polar organic compounds including benzene, toluene, and xylene.

• Anasorb® 747-Beaded carbon material that can collect a variety of both nonpolar and polar organic compounds.

• Carbotrap® and Carbosieve® -High surface area; useful for very volatile compounds (PPB Range).



48

TYPES OF SORBENT MATERIAL: INORGANIC SORBENTS

• Silica gel-Used to collect polar organic compounds such as alcohols, amines, and phenols.

Side Note: Electronic products are often packaged with a silica gel pouch as a dessicant since it readily adsorbs water vapor.



49

IMPINGERS INTRODUCTION

Impingers are specially designed glass bottles that are filled with a collection liquid specified in the sampling and analytical method. The fritted bubbler disperses the air and allows for better contact between the air sample and the impinger liquid.



50

SAMPLE COLLECTION WITH IMPINGERS A sample pump is used to bubble air through the impinger which contains a liquid reagent that has been specified in the method. The liquid will physically dissolve or chemically react with the chemical of interest.

Everyone hates impingers!



51

SAMPLE BAGS - INTRODUCTION • Used since the 1950’s to

collect a fixed volume of an air-contaminant mixture into a flexible container for subsequent analysis

• Called “grab” samples in industrial hygiene and “whole air” samples in environmental field.



52

SAMPLE COLLECTION WITH SAMPLE BAGS

Positive Pressure Negative Pressure



53

SAMPLE BAGS SPECIFIED IN SAMPLING METHODS

• Benzene in NIOSH 3700

• Carbon Dioxide in OSHA ID 172

• Carbon Monoxide in OSHA ID 210

• Ethylene Oxide in NIOSH 3702

• Nitrous Oxide by NIOSH 6000

• Sulfur hexafluoride in NIOSH 6602

• Trichloroethylene in NIOSH 3701

• Various hydrocarbons in EPA 0040 and EPA SOPs



TYPES OF SAMPLE BAGS Tedlar®

• Most commonly used sample bag

• Classic bag for 1-2 day storage of organic vapors

• Available with polypropylene or stainless steel fittings in a wide range of sizes

54

Standard FlexFoil-Suitable for gases and compounds not stable in Tedlar such as CO, CO2, H2,, methane, hydrogen sulfide or sulfur hexafluoride.



FOR PARTICULATES



56

DEFINING PARTICULATES Solid and liquid matter such as: • Dusts-particles rendered airborne during

crushing or grinding of rock-like material • Fumes-airborne solid particles formed

above molten metal, plastics or acid • Mists-droplets rendered airborne by

bubbling, boiling, spraying or splashing • Smokes-particles resulting from

incomplete combustion of organic matter



TYPES OF FILTER MEDIA MIXED CELLULOSE ESTER

APPLICATIONS • Asbestos, Fibers

25-mm with Conductive Cassette • Metals

37-mm with Clear Styrene Cassette • Oil Mist (Mineral)

37-mm with Clear Styrene Cassette 57



TYPES OF FILTER MEDIA POLYVINYL CHLORIDE

APPLICATIONS

• Particulates, Not Otherwise Classified • Chromic Acid and Hexavalent Chromium • NOW also being used by some labs for

metals • Silica with a respirable dust sampler

58



TYPES OF FILTER MEDIA GLASS FIBER/QUARTZ APPLICATIONS • Pesticides • Coal Tar Pitch Volatiles, Selected PAHs • PCB’s • Mercaptans, Isocyanates and more when

chemically coated • Diesel Particulate Matter (DPM)

59



TYPES OF FILTER MEDIA PTFE (TEFLON) APPLICATION • Specified in EPA methods for environmental

sampling of particulates in indoor or ambient air particulates.

• Specified in NIOSH methods for some

polyaromatic hydrocarbons (PAHs), Sodium Hydroxide and Metal Working Fluids.

60



61

CLOSED-FACE VS OPEN-FACE SAMPLING WITH CASSETTES

• Closed-face sampling refers to sample collection with the inlet piece of the filter cassette in place (and only the small plug removed).

• Open-face sampling refers to

sample collection with the entire inlet removed. This approach is used for asbestos using 25-mm conductive cassettes.



62

THE HAZARD POTENTIAL OF AIRBORNE PARTICULATES

Determined by: • Chemical composition • Mass concentration • Size characteristics



63

TRADITIONAL PARTICULATE SIZE-SELECTIVE CRITERIA • Total Dust

• Respirable Dust



64

TOTAL DUST SAMPLING IN THE BREATHING ZONE

INLE

T



Some regulations require the measurement of respirable dust.

Respirable dust is dust so small in size that it can get through the protective mechanisms of the human body and get down deep into the gas exchange region of the lung. To sample respirable dust, you will need to use a cyclone.

The smaller respirable particles will be collected onto the filter for subsequent analysis. Larger particles will fall into the grit pot and will be discarded.

Be sure to calibrate your pump to the flow rate specified to achieve the desired 50% cut-point.



When sampling with cyclones for Respirable Particulate

• NIOSH and ACGIH recommend a 4 micron cut-point. To achieve this the cyclone needs to be calibrated to the correct flowrate. ISO 7708 specifies a 50% (median) cut-point of 4 um.

The SKC aluminum cyclone – 2.5 l/min

Dorr-Oliver cyclone – 1.7 l/min



FOR ANY REGULATED CHEMICAL THE EXPOSURE LIMIT IS THE DRIVING FORCE

OSHA PERMISSIBLE EXPOSURE LIMIT (PEL) • 50 ug/m3 as an 8-hr TWA for all forms of

silica including quartz, cristobalite, and trydymite for all industry sectors covered by the rule.

• 25 ug/m3 action level (same as current TLV)

SO HOW CAN YOU SAMPLE SILICA TO MEET THE OSHA FINAL RULE?



INHALABLE SAMPLERS IOM SAMPLER FOR: THORACIC TLVs

Sulfuric acid • TLV of 0.2 mg/m3 Cotton Dust

• TLV of 0.1 mg/m3 Hard Metals containing Cobalt and Tungsten carbide as Co • TLV of 0.005 mg/m3


Industrial Hygiene Compliance 69

THORACIC PARTICULATE DEFINED

• Materials that are hazardous when deposited anywhere within the lung airways and the gas-exchange region.

• Thoracic samplers have a 50% cut-point of 10 um.



• Industrial Hygiene • Risk & Loss Control

• Safety • Indoor Air Quality

• Expert Testimony • Fit-Testing

Thank you !

Industrial Hygiene Air Sampling 101 (Basic) · 2019-04-11 · Industrial Hygiene Compliance 26 PUMP...

Documents

Transcript of Industrial Hygiene Air Sampling 101 (Basic) · 2019-04-11 · Industrial Hygiene Compliance 26 PUMP...