SIZE-SELECTIVE SAMPLING OF PARTICULATE MATTER

FOR OCCUPATIONAL HYGIENE

Presented by SKC Inc.

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

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.

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?

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.

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.

DEFINING AND MEASURING PARTICULATES

IN THE OCCUPATIONAL ENVIRONMENT

TRADITIONAL APPROACH

PARTICULATES IN THE WORKPLACE

Have traditionally been defined as:

TOTAL DUST RESPIRABLE DUST

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.

37-mm FILTER CASSETTE WITH FILTER

Inlet of Cassette

Filter

Support Pad

Outlet of Cassette

TOTAL DUST SAMPLINGIN THE BREATHING ZONE

Reference NIOSH Method 0500

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.

RESPIRABLE DUST SAMPLINGWITH CYCLONES

Reference NIOSH Method 0600

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.

DEFINING AND MEASURING WORKPLACE PARTICULATES

NEW CONCERNS, DEFINITIONS, AND SAMPLERS

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.

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 <http://www.osha.gov/dts/sltc/methods/inorganic/id215_v2/id215_v2.html>

NIOSH STATEMENTIN 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 <http://dx.doi.org/10.1080/15459620701493149>

ACCU-CAP EMERGESTO 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 225-8516GLA

PVC Filter

A NEW SOLU-CAP EMERGESIN 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 225- 8517)

Eliminates the need to wipe the inside of the cassette for analysis

Ensures all collected sample is analyzed

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.

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®).

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.

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.

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.

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.

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%.

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.

IOM SAMPLER: A GOLD STANDARD FOR INHALABLE DUST

SKC 225-70A

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.

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.

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.

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 225-772) 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.

IOM SAMPLERS FROM SKC

Plastic Sampler with Plastic Cassette-

SKC 225-70A

Lightweight for gravimetric analysis.

Plastic Sampler with Stainless Steel Cassette-SKC 225-79A

Suitable for chemical or gravimetric analysis.

IOM SAMPLERS FROM SKC

Stainless Steel Sampler with Stainless Steel Cassette-

SKC 225-76A

Can be autoclaved for bioaerosol sampling.

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 225-360

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.

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 225-67).

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 391-01. CALIBRATION ADAPTERfor the Button Sampler (shown here) is SKC 225-361.

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.

THORACIC TLVsAS OF 2014

Sulfuric acid-TLV of 0.2 mg/m3 as

thoracic particulate.Cotton Dust-TLV of 0.1 mg/m3 as thoracic particulate.

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.

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.

SKC THORACIC PPIs

REUSABLE SAMPLER

Made of anodized aluminum

DISPOSABLE SAMPLER

Made of conductive plastic

SKC 225-381SKC 225-386

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

COLLECTION EFFICIENCY CURVESOF THORACIC SAMPLERS

Aerodynamic Particle Diameter, da, m

0 5 10 15 20 25

Sa

mp

lin

g E

ffic

ien

cy,

E,

%

0

25

50

75

100

Thoracic Convention

GK2.69 Cyclone, 1.6 Lpm

PPI 10 m, 2.0 Lpm

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.

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.

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.

SKC CYCLONES AND FLOWRATESFOR 50% CUT-POINT OF 4 UM

SKC Aluminum Cyclone at 2.5 L/min

SKC 225-01-01 25 mm

SKC 225-01-02 37 mm

SKC CYCLONES AND FLOWRATESFOR 50% CUT-POINT OF 4 UM

SKC GS-3 Cyclone

at 2.75 L/min

SKC 225-103 25 mm

SKC 225-100 37 mm

SKC CYCLONES AND FLOWRATESFOR 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 225-105 SKC 225-69

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.

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 welder’s helmet or other PPE.

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 225-389) is also available for the disposable PPI.

4 L/min: 225-387

8 L/min: 225-384

2 L/min: 225-385

PPI SAMPLER PERFORMANCECOMPARED TO CRITERIA

0

25

50

75

100

1 10

Aerodynamic Particle Diameter, da, m

Pene

trati

on, P

, %

Respirable PPI, 2.0 L/min

Respirable PPI, 4.0 L/min

Respirable PPI, 8.0 L/min

ISO/CEN Respirable Criteria

5

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.

SKC 225-317 DPM Cassette with cyclone

DPM SAMPLER UTILIZES THREE STAGES

CycloneRemoves non-respirable particles that may overload the filter

Impactor inside the filter cassetteRemoves respirable particles greater than 1.0 um in diameter

Heat-treated quartz filterCollects particles less than 1.0 um in diameter for analysis of total or elemental carbon by NIOSH Method 5040

PORTABLE INSTRUMENT FOR MONITORING DUST EXPOSURES

SKC 770-4004

HAZ-DUST IV

Real-Time Dust Monitor based on light scattering (aerosol photometer)

Displays TWA, STEL, MIN, and MAX levels in mg/m3

Internal pump to collect sample with filter cassette simultaneously

Can add IOM sampler or GS cyclone to inlet for size-selection

NOTE ON CALIBRATION OF HAZ-DUST IV

Calibration Standard (SKC 770-140) 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.

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.

THANK YOU FOR TAKING THE TIME TO COMPLETE THIS TRAINING MODULE!

If you have further technical questions, email SKC at skctech@skcinc.com.