Transcript ADVANCES IN PARTICULATE SAMPLING

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
Outlet of Cassette
Support Pad
Filter
Inlet of Cassette
TOTAL DUST SAMPLING
IN 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 SAMPLING
WITH 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 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 <http://dx.doi.org/10.1080/15459620701493149>
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 225-8516GLA
PVC Filter
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
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 CassetteSKC 225-70A
Lightweight for gravimetric analysis.

Plastic Sampler with Stainless Steel CassetteSKC 225-79A
Suitable for chemical or gravimetric analysis.
IOM SAMPLERS FROM SKC

Stainless Steel
Sampler with Stainless
Steel CassetteSKC 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 ADAPTER
for 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 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.
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 225-381
SKC 225-386
PPI SCHEMATIC
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
COLLECTION EFFICIENCY CURVES
OF THORACIC SAMPLERS
Sampling Efficiency, E, %
100
75
PPI 10 m, 2.0 Lpm
GK2.69 Cyclone, 1.6 Lpm
Thoracic Convention
50
25
0
0
5
10
15
20
Aerodynamic Particle Diameter, da, m
25
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 FLOWRATES
FOR 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 FLOWRATES
FOR 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 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 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
2 L/min: 225-385

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 225389) is also available for the
disposable PPI.
8 L/min: 225-384
4 L/min: 225-387
PPI SAMPLER PERFORMANCE
COMPARED TO CRITERIA
100
Penetration, P, %
75
Respirable PPI, 2.0 L/min
50
Respirable PPI, 4.0 L/min
Respirable PPI, 8.0 L/min
ISO/CEN Respirable Criteria
25
0
1
5
Aerodynamic Particle Diameter, da, mm
10
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
 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
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
[email protected].