Transcript INHALABLE PARTICULATE MASS

INHALABLE PARTICULATE
MASS
HISTORY, CURRENT
TECHNOLOGY, AND DATA
CONSIDERATIONS
Presented by
TOTAL DUST:
HISTORY OF THE TERM

Except in cases where diseases are caused
by fine respirable dust, it has been common
practice to sample so-called total dust.
 This is in general recognition that all inhaled
particles could present either a specific or nonspecific risk to health. (Mark and Vincent, 1986.)
 Total dust, however, was never defined by a
specific size range and a 50% cut-point (D50)
was never established for total dust samplers.
THE FIRST DUST SAMPLERS:
U.S.A.

The initial work on dust sampling was done by
the US Bureau of Mines.
 In the 1920’s, impingers were used to collect
dust which was reported as TOTAL NUMBER
OF PARTICLES i.e. millions of particles per
cubic foot of air.
 Since impingers are cumbersome, health and
safety professionals in the U.S. replaced them
with 37-mm filter cassettes over time.
(Harper, 1997)
DUST SAMPLERS:
GLOBAL

Not all countries have standardized on 37-mm
filter cassettes for total dust sampling.
 Given the vague definition of total dust, a
number of personal samplers with various
performance characteristics have been used
for sampling total dust around the world.
TOTAL DUST SAMPLERS:
UNITED KINGDOM

Single Hole Lead
Head for MDHS 6
SKC 225-52

Seven Hole Head for
MDHS 14
SKC 225-50
SURPRISING STATISTICS:
SAMPLER PERFORMANCE


There is very limited data available on how well these
samplers actually measure the true dust exposure.
Studies show considerable differences in results from
these various samplers when sampling the very same
dust under the identical environmental conditions.
≠
≠
SURPRISING STATISTICS:
LIMITATIONS OF 37-MM CASSETTES
37-mm Filter Cassettes:




Were never designed to represent a “physiologically
relevant exposure” to the respiratory system.
Aspiration efficiency is not very similar to the nose and
mouth.
Are not 100% efficient in collecting all sizes of dust
particles.
Have a upper size limit (approx. 30 um) where
efficiency falls to zero.
(T. Renee Anthony, AIHCE 2011)
SURPRISING STATISTICS:
ERRORS WITH 37-MM CASSETTES
Sampling errors with 37-mm cassettes can
be evidenced from:

Ambient wind velocity effects
 Orientation effects
 Dust deposition on walls of cassette
SO WHY DO WE USE THEM?
In the U.S., we have been using 37-mm
cassettes because:




“Reductions in exposures as measured with these
have been associated with reductions in health
effects”.
Cheap and Easy
Used by compliance officers
History-Years of data on file
SEARCHING FOR A BETTER WAY
NEW CRITERIA FOR DUST SAMPLING
Beginning in the
1980’s, occupational
hygiene experts from
around the world
began to investigate a
better way to
evaluate particulates in
the workplace.


First, was the need for
standards (guidelines)
that reflect closely the
nature of human
exposure.
Secondly, was the need
for samplers that collect
the “physiologically
relevant” size fraction of
interest.
WHY CHANGE?

Measuring dust concentrations with the same
efficiency as we inhale them makes better
sense when evaluating the health-related
dose.
SEARCHING FOR A BETTER WAY
NEW CRITERIA FOR STANDARDS

Committees from
ISO, CEN, and
ACGIH have come
to an agreement on
new criteria.
 Many occupational
hygiene bodies
around the world
have now adopted
this criteria.

Health-related
sampling should be
based on the
following particle
size-selective
fractions:
Inhalable, Thoracic,
and Respirable.
NEW CRITERIA:
DESCRIPTIONS
Inhalable-the fraction that enters the nose and/or mouth
during breathing (D50 of sampler= 100 um)
Thoracic-the sub-fraction of inhalable that penetrates
into the respiratory tract below the larynx
(D50 of sampler= 10 um)
Respirable-the sub-fraction of inhalable that penetrates
to the alveolar region of the lung. (D50 of sampler= 4 um)
(AIHA Aerosol Committee Publication)
NEW CRITERIA:
ILLUSTRATION
•Inhalable
•Thoracic
•Respirable
ACGIH:
ADOPTED NEW CRITERIA
In 1993, revisions to the Appendix “Particle
Size-Selective Sampling Criteria for Airborne
Particulate Matter” were made by ACGIH.
 At this time, ACGIH adopted and defined
inhalable, thoracic, and respirable particulate
mass fractions.


See page 78 of the 2014 TLV handbook.
NIOSH:
STATUS OF NEW CRITERIA

NIOSH has NOT formally adopted the new
criteria in total.
 Inhalable-NIOSH Method 5700 for
formaldehyde on dust is the only method.
 Thoracic-NIOSH Method 5524 for
metalworking fluids is the only method.
 Respirable-NIOSH Methods for respirable dust
now specify a cyclone with a D50 of 4 um with
several options listed. Ex. See Definition on
upper left of NIOSH Method 0600.
OSHA:
STATUS OF NEW CRITERIA

U.S. OSHA has not officially adopted the new
criteria as it requires Congressional action like
with PEL updates.
 OSHA Letter: SKC has a letter on file
indicating that the IOM Sampler is “more
efficient” in sampling small and large particles
than 37-mm cassettes and can be used for
compliance sampling of particulates not
otherwise regulated.
OSHA:
STATUS OF NEW CRITERIA

In the OSHA Notice of Proposed Rulemaking
on Respirable Crystalline Silica, OSHA
indicates that measurement should be
determined by a sampling device designed to
meet ISO 7708:1995 (page 538).
 This will harmonize OSHA’s practice with
current aerosol science and most other
agencies around the world including ACGIH
and NIOSH.
INHALABLE PARTICULATE MASS:
DEFINED

Those materials that are hazardous when
deposited anywhere in the respiratory tract
 Includes particulate matter that enter the head
airways region including the nose and mouth
 Also includes materials that can produce
systemic toxicity from deposition anywhere in
the respiratory system.
INHALABILITY CRITERION:
FURTHER COMMENTS

The current criterion for inhalable dust is not
perfect, but represents a best-guess based on
decades of research.
 A known flaw: The current inhalability criterion
underestimates human intake in calm air and
low velocity environments.
(Volckens, AIHCE 2011)
DUST SAMPLERS
TO MEET THE NEW CRITERIA

After the creation of new
criteria for standards
researchers began to
develop new samplers
to meet the new criteria.

These new sampling
devices were designed
to collect a biologically
relevant fraction of dust
found in the workplace.
THE IDEAL INHALABLE SAMPLER


An inhalable sampler is considered ideal “when a
personal sampler mounted on the body gives the
same measured dust concentration and aerodynamic
size distribution as that inspired by its wearer,
regardless of dust source location and wind
conditions”. (Mark and Vincent, 1986)
(Note: Inhalable dust was originally called inspirable
dust.)
Inhalable samplers have a D50 of 100 microns.
37-MM FILTER CASSETTES

Do not effectively sample the inhalable
fraction.
 They significantly underestimate the
concentration of larger dust particles from
30-100 um.
 Of particular concern are sample losses that
occur from particles that adhere to the interior
cassette walls.
JOEH ARTICLE BY NIOSH
NIOSH Researchers report:

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.
 Results of wiped 37-mm filter cassettes are a closer
match to results from inhalable samplers.
(Ashley, Harper, Demange, 2007)
INHALABLE SAMPLERS:
DESIGNED FOR THE NEW CRITERIA



The first personal sampler specifically designed for
inhalable particulate mass was developed by Mark
and Vincent in 1986 at the Institute of Occupational
Medicine in Scotland.
The sampler was named the IOM sampler and SKC
Ltd. in the UK was the sole licensee and exclusive
manufacturer of this sampler for more than 20 years.
The patent has now expired, but SKC is still the only
company that can call this device the IOM Sampler.
IOM SAMPLER
A GOLD STANDARD
Exploded View
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 humidity
conditions then weigh them as a unit.
 Allow the assembly to stabilize a few
minutes before taking a reading.
 Note: Do not desiccate the filter/cassette.
USING THE IOM SAMPLER
GRAVIMETRIC ANALYSIS

Place the IOM cassette/filter assembly into the
sampler body, screw on the cover cap, and
connect to the pump.
 Calibrate the flowrate to 2 L/min using the IOM
calibration adapter or by placing in a
calibration jar.
 Following sample collection, weigh the
cassette/filter assembly again.
 Referenced in HSE Method MDHS 14/3
INHALABLE PLUS RESPIRABLE
WITH GRAVIMETRIC ANALYSIS

Aerosol physicists at the UK Health & Safety
Laboratory have published on the use of
polyurethane foam discs (SKC 225-772) inserted
into the front of the IOM cassette for sizeselective sampling. (Kenny, Chung, et. al., 2001)
 The foam scrubs out large inhalable particles.
 Dust on Filter = Respirable fraction
 Dust on Filter + Foam = Inhalable fraction
USING THE IOM SAMPLER
WITH OTHER TYPES OF ANALYSES

The IOM Sampler is also
available with a stainless
steel cassette.

(SKC 225-79A)

This cassette is typically
used for chemical
(elemental) analysis
where a solvent rinse is
done inside the
cassette.
A stainless steel IOM
body along with a
stainless steel cassette
is available for those
using the sampler for
bioaerosol sampling.
(SKC 225-76A)

This model allows for
autoclaving.
ADVANTAGES OF THE IOM

Developed specifically to match the inhalable
definition.
 Best fit with the inhalable curve under many
circumstances.
 Internal wall deposits are included in the
sample analysis.
 Can be combined with a foam insert to collect
the respirable fraction simultaneously.
DISADVANTAGES OF THE IOM

Tends to oversample in low wind speed and
when large particles are present.
 Large inlet allows sampling of large projectiles
(Ex. Blasting operations)
 Higher limit of quantitation due to weighing of
cassette.
 Designed as a personal sampler only; not for
area sampling.
(Volckens, AIHCE 2011)
WEIGHING ACCURACY OF IOM
SAMPLES
CONCERNS
RESPONSE


March/April 1999
AIHA Journal
article discussed
problems of water
absorption by
plastic IOM
cassette and
resulting instability
of the tare weight



The type of plastic
material was
changed to address
water adsorption.
Do not desiccate
Equilibrate under
controlled humidity
conditions.
Consider stainless
steel cassettes if
necessary.
OTHER INHALABLE SAMPLERS:
FROM SKC
Button Sampler



Developed by Univ of
Cincinnati
Inlet has a stainless
steel inlet screen with
numerous, evenly
spaced holes.
Screen keeps out large,
non-inhalable projectiles
from impacting or
splashing onto the filter.
SKC 225-360
USING THE BUTTON SAMPLER
SAMPLE LOGISTICS

Unscrew the sampler inlet and remove the
Teflon® O-ring.
 Place a 25-mm filter on the stainless steel
support screen, replace the 0-ring and the
sampler inlet.
 Calibrate the Button Sampler to a flowrate of
4 L/min using the calibration adapter or by
placing in a calibration jar.
USING THE BUTTON SAMPLER
SAMPLE LOGISTICS

A filter pore size of 1.0 um or higher is
recommended due to the backpressure
limitations of most personal samplers.
 After sampling, remove the filter for analysis.
 Use a conductive plastic filter transport case
(SKC 225-67) or Filter-Keeper (SKC 225-8301)
for shipment to the lab.
ADVANTAGES OF BUTTON
SAMPLER






Good precision and fit with the inhalable
curve
Inlet screen keeps out large particles
Low sensitivity to wind velocity and
direction
Uniform collection on the filter
Flow rate of 4 L/min for personal
sampling increases sensitivity
Can be used for personal or area
sampling
DISADVANTAGES OF BUTTON
SAMPLER

Inlet holes can become clogged (i.e. flour dust)
 Liquid aerosols not collected as efficiently as
solid aerosols
 Dust deposited on sampler walls and O-ring
are not included in sample analysis.
OTHER INHALABLE SAMPLERS:
FROM SKC IN UK
7-HOLE SAMPLING HEAD

Traditional European method using a 25-mm filter and
cassette with an end cap with 7 equispaced inlet holes
with flows of 2.0 L/min.

Listed in HSE MDHS Method 14, but not widely
studied.
7-HOLE (DEAD) HEAD ??
INHALABLE SAMPLERS:
FROM OTHER SUPPLIERS
Conical Inhalable
Sampler (CIS)
Also known as the GSP
Sampler. This German
sampler aspirates
particles through the
inlet at 3.5 L/min onto a
37-mm filter. Limited
commercial availability.
CIS SAMPLER
INHALABLE SAMPLERS:
FROM OTHER SUPPLIERS
CIP-10
A French sampler with
2 key components:
1. Impactor/foam
pre-separator to retain
large particles
2. A rotating cup with a
PUF ring that collects the
sample for gravimetric
analysis
CIP-10
SAMPLER
INHALABLE SAMPLING OF
BERYLLIUM: REUSE ISSUES

SKC consulted with
NIOSH for advice on
decontamination and
reuse of inhalable
samplers used
to sample beryllium.


NIOSH does not
clean/reuse these
cassettes due to safety and
cross-contamination
concerns with Be.
They recommend using 37mm cassettes and wiping
the walls to account for wall
losses. The results will be
comparable to those using
inhalable samplers.
DATA CONSIDERATIONS
2014 INHALABLE TLVs®











Acrylamide
Alachlor
Aldrin
Asphalt Fume
Atrazine
Azinphos-methyl
Barium Sulfate
Benomyl
Beryllium
Borate cpds, Inorganic
Butylated hydroxytoluene











Calcium sulfate
Caprolactam
Captan
Carbaryl
Carbofuran
Carbon Black
Chlorpyrifos
Citral
Clopidol
Coumaphos
Cresol, all isomers
DATA CONSIDERATIONS
2014 INHALABLE TLVs®











Demeton (and Demeton- Smethyl)
Diazinon
Dibutyl phosphate
2,2-Dichloropropionic acid
Dichlorvos (DDVP)
Dicrotophos
Dieldrin
Diesel Fuel
Diethanolmine
Diethylene glycol monobutyl
ether
Dioxathion












Diquat
Disulfoton
Endosulfan
EPN
Ethion
2-Ethylhexanoic acid
Fenamiphos
Fensulfothion
Fenthion
Ferbam
Flour Dust
Fonofos
DATA CONSIDERATIONS
2014 INHALABLE TLVs®












Glyoxal
Hexahydrophthalic anhydride
Iodine and Iodides
Isobutyl nitrite
Magnesium oxide
Malathion
Maleic anhydride
Manganese
Methomyl
Methyl demeton
Methyl parathion
Mevinphos









Mineral oil, excluding metal
working fluids
Molybdenum (Metal and
insoluble cpds.)
Monochloroacetic acid
Monocrotophos
Naled
Natural rubber latex as total
proteins
Nickel, Elemental, Soluble
and Insoluble Cpds.
Nickel Subsulfide
5-Nitro-o-toluidine
DATA CONSIDERATIONS
2014 INHALABLE TLVs®









p,p-Oxybis(benzene
sulfonyl hydrazide)
Parathion
Particulates Not Otherwise
Specified (now a guideline;
not a TLV)
Pentachlorophenol
Peracetic Acid (PAA)
Phorate
m- and o-Phthalodinitrile
Piperazine and salts







Ronnel
Silicon carbide, nonfibrous
Sulfotepp (TEDP)
Sulprofos
Synthetic Vitreous Fibers
(Continuous filament)
Temephos
Terbufos
1,1,2,2-Tetrabromomethane
DATA CONSIDERATIONS
2014 INHALABLE TLVs®






Tetrethyl pyrophosphate
(TEPP)
Thallium
4,4-Thiobis(6-tert-butyl-mcresol)
Thiram
Tributyl phosphate
Trichlorphon




Trimellitic anhydride
Vanadium pentoxide
Wood Dusts
Xylidine (mixed isomers)
2014 INTENDED CHANGES TO TLVs®
ISSUED AS INHALABLE








Calcium Silicate
Ethylene Glycol
Lithium hydride
Simazine
2,4- or 2,6- Toluene
diisocyanate
Trimetacresyl phosphate
Triorthocresyl phosphate
Triparacresyl phosphate
For TLVs with IFV notation
(Inhalable fraction and
vapor)


May require 2 separate
samples due to flowrate
issues for each
contaminant phase.
Chemically coated filters
provide a solution for
TDI.
DATA CONSIDERATIONS
TOTAL VS INHALABLE
KEY REFERENCES


Journal article-Werner, et al. (1996) Investigation into
the impact of introducing workplace aerosol standards
based on the inhalable fraction. Analyst 121:12071214.
AIHCE 2011 Session-T. Renee Anthony. How to
Relate Total and Inhalable Dust Exposures. From the
session entitled Inhalable Particles: The State of the
Science on a Big Particle Problem. (An electronic
copy of this is available upon request.)
DATA CONVERSION??
TOTAL VS INHALABLE

Inhalable particulate mass is typically greater
than total particulate mass.
 How much greater will depend upon the SIZE
of the particles.
 With larger particles, inhalable particulate
mass will be much greater than total
particulate mass.
 With smaller particles, inhalable and total
particulate mass will be comparable.
DATA CONVERSION??
TOTAL VS INHALABLE
Type of particulate
Ratio of Results
IOM/37-mm cassette
Dust from powder handling, grinding
Mist from paint spray or oil mist
Hot Processes such as foundries
Fumes from Welding
*Werner, et al. (1996)
2.5
2.0
1.5
1.0
DATA CONVERSION??
TOTAL VS INHALABLE
Dr. Anthony’s AIHCE 2011 session makes the
point that it is really not enough to use a
simple conversion factor as given on the
previous slide.
 Ratio of results can also vary with particle size
distribution.
 “Using a standard correction factor without
knowing your aerosol distribution may underor over-estimate inhalable-converted exposure
levels.”

DATA CONVERSION??
TOTAL VS INHALABLE
So what do you do?

Collect both 37-mm
cassette and
inhalable samples
and determine
process-specific
ratios for YOUR
unique operation.
SIDE-BY-SIDE SAMPLING:
37-MM VS INHALABLE SAMPLERS

Will bridge your past
data using total dust
filter cassettes to
that using inhalable
samplers.
 Will provide backup
data for any
compliance related
issues.
THANKS FOR YOUR ATTENTION.
PLEASE EMAIL SKC WITH ANY QUESTIONS ON SAMPLING.
[email protected]