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SIZE-SELECTIVE SAMPLING OF PARTICULATE MATTER FOR OCCUPATIONAL HYGIENE Presented by SKC Inc.

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Presentation on theme: "SIZE-SELECTIVE SAMPLING OF PARTICULATE MATTER FOR OCCUPATIONAL HYGIENE Presented by SKC Inc."— Presentation transcript:

1 SIZE-SELECTIVE SAMPLING OF PARTICULATE MATTER FOR OCCUPATIONAL HYGIENE Presented by SKC Inc.

2 AIRBORNE PARTICLES Include solid and liquid matter such as: Dusts- solid particles that become airborne during crushing of rock-like material Fumes- microscopic particles generated during welding and other operations Mists- liquid droplets in air Smokes- particles generated from incomplete combustion or burning

3 CLARIFICATIONS The word dust is used in the occupational health and safety profession and throughout this training module as a general term for particulate matter and airborne particles. Do not be confused by the general use of this term. Asbestos and other fibers are also hazardous particulate matter found in the workplace. Fibers however will not be covered in this training module.

4 HEALTH EFFECTS OF AIRBORNE PARTICLES Are determined by three parameters: Chemical Composition-What is the chemical makeup of the particulate matter? Mass Concentration-How much particulate matter is being inhaled by exposed persons? Size Characteristics-How big are the individual particles?

5 PARTICLE SIZE: A CRITICAL PARAMETER The size of the airborne particles will determine where they will deposit in the respiratory system. Smaller particles are more hazardous as they will deposit deep into the lower regions of the lung and can enter the bloodstream.

6 PARTICLE SIZE: DETERMINES HEALTH EFFECTS Government regulations and exposure guidelines have been issued for some compounds based on their particle size. These size-selective exposure limits specify different allowable levels for smaller versus larger particles of the same material.

7 DEFINING AND MEASURING PARTICULATES IN THE OCCUPATIONAL ENVIRONMENT TRADITIONAL APPROACH

8 PARTICULATES IN THE WORKPLACE Have traditionally been defined as: TOTAL DUST RESPIRABLE DUST

9 TOTAL DUST Is collected by using a filter of a type and pore size as specified in the published sampling and analytical method for that compound. The filter is loaded into a cassette and connected to a sampling pump that has been calibrated to a flowrate of at least 1 L/min. Samples are collected in a fixed point location or in the breathing zone of workers.

10 37-mm FILTER CASSETTE WITH FILTER Inlet of Cassette Filter Support Pad Outlet of Cassette

11 TOTAL DUST SAMPLING IN THE BREATHING ZONE Reference NIOSH Method 0500

12 RESPIRABLE DUST Is also collected onto a filter of a type and pore size that is specified in the sampling and analytical method for designed compounds. Preceding the filter, however, is a size-selective sampler such as a cyclone that will separate the respirable fraction from the non-respirable fraction when connected to a pump sampling at the designated flow rate for that specific device.

13 RESPIRABLE DUST SAMPLING WITH CYCLONES Reference NIOSH Method 0600

14 CYCLONE OPERATION Function on the same principle as a centrifuge. When the air comes in through a small slit opening on the side, cyclonic action occurs within the stem of the sampler. Large (non-respirable) particles hit the side of the cyclone and fall into the cap (grit pot) at the bottom of the cyclone and are discarded. Smaller respirable particles are thrown upwards onto the filter and are analyzed.

15 DEFINING AND MEASURING WORKPLACE PARTICULATES NEW CONCERNS, DEFINITIONS, AND SAMPLERS

16 NEW CONCERN WITH TRADITIONAL FILTER CASSETTES US NIOSH and OSHA scientists have been addressing sample losses with traditional 37-mm filter cassettes. Of particular concern, are sample losses that occur from particles that adhere to the interior cassette walls and are not analyzed.

17 OSHA STATEMENT: HEXCHROME METHOD ID 215; VERSION 2 Tests showed that Cr (VI) equivalent to 0 to 123% of the amounts found on the PVC filter were present on the interior walls of cassettes used for compliance samples. It is now routine procedure to wipe interior walls of sampling cassettes for all metal samples analyzed. Source: United States. Occupational Safety and Health Administration. Hexavalent Chromium. 30 Apr 2009

18 NIOSH STATEMENT IN AIHA JOURNAL ARTICLE Dust deposits on the walls of filter cassettes were 19% of the total sample for lead and 25% of the total sample for copper. Filter cassettes should be rinsed and wiped prior to analysis. Source: Ashley, Kevin, Harper, Martin and Demange, Martine. Concerning Sampler Wall Deposits in the Chemical Analysis of Airborne Metals. Journal of Occupational and Environmental Hygiene 4:9 Sept 2007: D81 - D86

19 ACCU-CAP EMERGES TO ADDRESS CONCERNS Filter insert that is placed into a 2-piece cassette with support pad. Consists of a clear plastic dome heat-sealed to a filter. Dust is collected onto the filter or within the dome for gravimetric analysis. SKC GLA PVC Filter

20 A NEW SOLU-CAP EMERGES IN 2013 Designed for the measurement of metals using chemical analysis Acid digestible dome material heat sealed to mixed cellulose ester filter Pre-loaded into 2-piece cassettes with support pads (SKC ) Eliminates the need to wipe the inside of the cassette for analysis Ensures all collected sample is analyzed

21 NEW SIZE FRACTIONS FOR PARTICULATES Many occupational hygiene agencies and standard setting bodies around the world have abandoned the 2 traditional size fractions of total and respirable dust and have instead defined 3 particulate size fractions.

22 NEW SIZE FRACTIONS FOR PARTICULATES Inhalable Particulate Matter Thoracic Particulate Matter Respirable Particulate Matter Note that U.S. OSHA and MSHA have not adopted these new size fractions for particulates. They still measure and regulate total and respirable fractions. ACGIH has adopted these new size fractions for their Threshold Limit Values (TLVs ® ).

23 Illustration of the 3 new particulate fractions adopted by most occupational hygiene organizations and standard setting bodies around the world including ACGIH, ISO, and CEN.

24 NOTES ABOUT CUT-POINT You will frequently see the term 50% or median cut-point used to describe the performance of size-selective samplers like cyclones. It is important to understand this term.

25 NOTES ABOUT CUT-POINT Sampling devices are not 100% efficient in collecting all sizes of particles from microscopic fumes to large dusts. The particle size that the sampling device collects with a 50% efficiency is described as the 50% or median cut-point.

26 CONSIDER A VACUUM CLEANER Vacuum cleaners do not pick up all sizes of particles with the same efficiency. A vacuum cleaner may be 100% efficient in collecting a small piece of dust; 0% effective for a big stone. There is a size where the vacuum is 50% efficient.

27 NOTES ABOUT CUT-POINT A size-selective sampler will always have the 50% cut-point specified for a designated flowrate. Particles smaller than the 50% cut-point will be collected with an efficiency greater than 50%. Particles larger than the 50% cut-point will be collected with an efficiency less than 50%.

28 INHALABLE PARTICULATE: A NEW PARTICULATE SIZE-FRACTION The new term for total dust. Is defined as dust that is hazardous when deposited anywhere in the respiratory system including the nose and mouth. Is collected using a sampler designed and tested to capture this size of particulate matter. Inhalable samplers have a 50% cut-point of 100 um.

29 IOM SAMPLER: A GOLD STANDARD FOR INHALABLE DUST SKC A

30 USING THE IOM SAMPLER: GRAVIMETRIC ANALYSIS Load a 25-mm filter into the cassette using forceps and wearing gloves. Equilibrate the filter/cassette assembly overnight under controlled conditions, then weigh them as a unit. Collect the sample at 2 L/min. Equilibrate and weigh again for sample analysis.

31 THE IOM ADVANTAGE: NO SAMPLE LOSS Since the filter and cassette are weighed together, all particles which are drawn in through the sampling inlet are part of the analysis. Any particulate dislodged from the filter due to accidental knocking, will be retained inside the cassette and weighed.

32 USING THE IOM SAMPLER: FOR CHEMICAL ANALYSIS For this application, the stainless steel cassette is frequently used. The stainless steel cassette is often preferred since the lab will use chemical solvents to rinse the cassette for analysis.

33 IOM SAMPLER FOAM DISCS: FOR SIMULTANEOUS INHALABLE AND RESPIRABLE SAMPLING Multi-Dust Foam Discs Developed by the UK Health and Safety Laboratory A foam plug ( SKC ) is inserted into the IOM cassette in front of the filter Larger particles are trapped in the foam plug; smaller particles in the filter. Dust collected on filter only is the respirable fraction. Filter plus foam is inhalable fraction.

34 IOM SAMPLERS FROM SKC Plastic Sampler with Plastic Cassette- SKC A Lightweight for gravimetric analysis. Plastic Sampler with Stainless Steel Cassette- SKC A Suitable for chemical or gravimetric analysis.

35 IOM SAMPLERS FROM SKC Stainless Steel Sampler with Stainless Steel Cassette- SKC A Can be autoclaved for bioaerosol sampling.

36 ALTERNATIVE INHALABLE SAMPLER Button Sampler Inlet has a screen to keep out large, non-inhalable particles. Uses higher flow rate which enhances sensitivity of measurement for compounds with low exposure limits. SKC

37 USING THE BUTTON SAMPLER: SAMPLE LOGISTICS Unscrew the sampler inlet and remove the O-ring. Place a 25-mm filter on the stainless steel support screen, replace the 0-ring and the sampler inlet. Collect the sample at a flowrate of 4 L/min. After sampling, remove and transport the filter only to the laboratory.

38 USING THE BUTTON SAMPLER: SAMPLE LOGISTICS A filter with a pore size of 1.0 um or larger is recommended to keep pressure drop low. Otherwise, the pump may fault with any accumulation of sample on the filter due to excessive backpressure. Since there is no cassette with the Button Sampler, users will need to have a device to transport the filters with collected sample to the laboratory. Options include conductive filter transport cases (SKC ).

39 TIPS ON CALIBRATION SKC offers calibration adapters that allow the IOM and Button Samplers to be directly attached to external flowmeters including the Defender primary flow calibrators. CALIBRATION ADAPTER for the IOM Sampler is SKC CALIBRATION ADAPTER for the Button Sampler (shown here) is SKC

40 THORACIC PARTICULATE Defined as those 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. Thoracic region includes bronchioles as well as air sacs in the lower lung.

41 THORACIC TLVs AS OF 2014 Sulfuric acid- TLV of 0.2 mg/m3 as thoracic particulate. Cotton Dust- TLV of 0.1 mg/m3 as thoracic particulate.

42 THORACIC NIOSH METHOD Metalworking Fluids NIOSH Method 5524, Issue 1 specifies a 2-um PTFE filter in a 37-mm filter cassette with an optional thoracic particulate sampler. At the time the method was published, the only thoracic sampler available commercially was a cyclone from BGI Incorporated.

43 SKC THORACIC SAMPLERS Thoracic Parallel Particle Impactors (PPI) Designed to give a precise match to the thoracic criteria Used with any suitable 37-mm filter at 2 L/min SKC thoracic PPIs are not listed in the NIOSH method for metalworking fluids since the samplers were developed after the method was published.

44 SKC THORACIC PPIs REUSABLE SAMPLER Made of anodized aluminum DISPOSABLE SAMPLER Made of conductive plastic SKC SKC

45 Plate with four suitably sized inlet orifices Plate with disposable, pre-oiled porous plastic impaction substrates and outlet orifices Main collection filter (37mm) and filter support pad or screen Outlet to pump 2 LPM PPI SCHEMATIC

46 COLLECTION EFFICIENCY CURVES OF THORACIC SAMPLERS

47 DEFINITIONS OF RESPIRABLE PARTICULATES Throughout the history of occupational air sampling, several definitions of respirable particulate matter have been adopted by various organizations around the world. All definitions describe respirable particulate as that small enough to reach the gas-exchange region. Differences involve the 50% (median) cut-point of respirable dust samplers.

48 DEFINITIONS OF RESPIRABLE DUST SAMPLERS The British Medical Research Council (BMRC) originally defined respirable dust samplers as having a 50% cut-point of 5 microns. In the US, OSHA/MSHA define respirable dust samplers as having a 50% cut-point of 3.5 microns. OSHA is trying to change/update this definition in their 2013 Notice of Proposed Rulemaking on silica.

49 A CONSENSUS DEFINITION ON RESPIRABLE DUST SAMPLERS In an attempt, to reach a global consensus on the definition of respirable dust in the workplace, a compromise definition was developed for respirable dust samplers specifying a 50% cut-point of 4 microns.

50 SKC CYCLONES AND FLOWRATES FOR 50% CUT-POINT OF 4 UM SKC Aluminum Cyclone at 2.5 L/min SKC mm SKC mm

51 SKC CYCLONES AND FLOWRATES FOR 50% CUT-POINT OF 4 UM SKC GS-3 Cyclone at 2.75 L/min SKC mm SKC mm

52 SKC CYCLONES AND FLOWRATES FOR 50% CUT-POINT OF 4 UM SKC GS-1 Cyclone at 2.0 L/min SKC Plastic Cyclone at 2.2 L/min (From SKC Ltd. in UK) SKC SKC

53 A NEW RESPIRABLE DUST SAMPLER FROM SKC SKC has developed a new impaction based sampler for respirable dust called the Parallel Particle Impactor or PPI. The PPI was designed to improve performance characteristics evidenced with older traditional cyclones.

54 SKC RESPIRABLE PPI: FUNCTIONALITY The disposable models of the PPI look and function very much like a traditional 37-mm cassette. But the inlet comes pre-loaded with size-selective impactor plates that scrub out non-respirable dust. PPI samplers are smaller than traditional cyclones and can fit under a welders helmet or other PPE.

55 SKC RESPIRABLE PPI: FLOWRATES Single-use, disposable PPI models are available for use at either 2, 4, or 8 L/min. This provides flexibility in pump option and sample duration for various airborne concentrations. A calibration adapter (SKC ) is also available for the disposable PPI. 4 L/min: L/min: L/min:

56 PPI SAMPLER PERFORMANCE COMPARED TO CRITERIA

57 SUB-MICRON RESPIRABLE DUST: DIESEL PARTICULATE MATTER (DPM) In a coal mine, workers may be exposed to both respirable coal dust and respirable DPM. Sampler was developed by NIOSH to separate these two contaminants based on particle size. DPM is less than 1.0 um in size Coal dust is greater than 1.0 um.

58 SKC DPM Cassette with cyclone

59 DPM SAMPLER UTILIZES THREE STAGES Cyclone Removes non-respirable particles that may overload the filter Impactor inside the filter cassette Removes respirable particles greater than 1.0 um in diameter Heat-treated quartz filter Collects particles less than 1.0 um in diameter for analysis of total or elemental carbon by NIOSH Method 5040

60 PORTABLE INSTRUMENT FOR MONITORING DUST EXPOSURES SKC

61 HAZ-DUST IV Real-Time Dust Monitor based on light scattering (aerosol photometer) Displays TWA, STEL, MIN, and MAX levels in mg/m 3 Internal pump to collect sample with filter cassette simultaneously Can add IOM sampler or GS cyclone to inlet for size-selection

62 NOTE ON CALIBRATION OF HAZ-DUST IV Calibration Standard (SKC ) is a metal adapter that causes a known value to appear on LCD. The instrument will have a k value assigned by the factory when it is new. The k value should not deviate more than 10% during subsequent checks.

63 NOTE ON CALIBRATION OF HAZ-DUST IV Haz-Dust monitors are factory calibrated using Arizona Road Dust (ARD). For higher accuracy, users can collect concurrent samples using filter cassettes, compare lab results to LCD readings, and generate a correction factor for their particular dust under study.

64 THANK YOU FOR TAKING THE TIME TO COMPLETE THIS TRAINING MODULE! If you have further technical questions, SKC at


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