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THE EMERGENCE OF NEW DUST SAMPLERS FOR
NEW ISSUES
SPECIAL FOCUS: 2013 OSHA PROPOSED RULEMAKING ON SILICA
WHY DO WE NEED NEW DUST SAMPLERS?
New concerns with traditional samplers New criteria for size-selective sampling New regulations and guidelines New priorities and demands from users
NEW CONCERNSWITH TRADITIONAL SAMPLERS
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.
U.S. OSHA STATEMENTIN HEXAVALENT CHROMIUM METHOD
“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.
PVC ACCU-CAP FOR GRAVIMETRIC ANALYSIS
A NEW SOLU-CAP EMERGESBASED ON NIOSH RESEARCH
Designed for chemical analysis of metals Mixed cellulose ester filter heat sealed to acid
digestible cellulose acetate dome Pre-loaded into 2-piece cassettes with
support pads Eliminates the need to wipe the inside of the
cassette to obtain reliable exposure measurements Source: Ashley, Kevin, Harper, Martin. “Acid-Soluble
Internal Capsules for Closed-Face Cassette Elemental Sampling and Analysis of Workplace Air.” Journal of Occupational and Environmental Hygiene 10:6, 297-306, February 25, 2013.
NEW CRITERIAFOR SIZE-SELECTIVE SAMPLING
In 1993, ACGIH joined with ISO and CEN in defining particulates in terms of inhalable, thoracic, and respirable particulate mass fractions.
See page 80 of the 2013 TLV handbook.
NOTE FOR NEWCOMERS:CURRENT PARTICULATE FRACTIONS
Inhalable-particles that are hazardous when deposited anywhere in the respiratory system (including those that enter nose/mouth)
Thoracic-particles hazardous when deposited
anywhere within the lung airways and gas-
exchange region Respirable-particles hazardous when deposited
in the alveolar gas-exchange region.
PERFORMANCE SPECS FOR DUST SAMPLERS
Aerodynamic Particle Diameter, da, m
1 10 100
Sam
plin
g E
ffic
ien
cy, E
, %
0
25
50
75
100
Inhalable
ThoracicRespirable
INHALABLE PARTICULATE:A CLOSER LOOK
Review of pertinent scientific issues presented at an AIHCE sessionThe impact on dust samplers
HISTORICAL PERSPECTIVE: TERMS AND SPECIFICATIONS
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 non-specific risk to health. (Mark and Vincent, Ann. Occup. Hyg.,1986.)
PROBLEMS WITH TOTAL DUST:SPECIFICATIONS
Total dust has never been defined by a specific size range and a 50% cut-point (D50) was never established for total dust samplers.
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.
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. (Mark and Vincent, 1986)
≠≠
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 occur from: Ambient wind velocity effects Orientation effects Dust deposition on walls of cassette
INHALABLE SAMPLERS EMERGE
Since occ hygienists are concerned with the health-related dose, new dust samplers have emerged that measure dust concentrations with the same efficiency as we inhale them.
THE IDEAL DUST 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)
Inhalable samplers have a 50% cut-point of 100 microns.
INHALABLE SAMPLERS: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 and was licensed to SKC Ltd. in the U.K.
SKC 225-70A
ADVANTAGES OF THE IOM SAMPLER: TECHNICAL
Developed specifically to match the inhalable definition.
Precise fit to the inhalable curve at 2 L/min Conductive plastic cassette for gravimetric and
stainless steel cassette for chemical analysis. Internal wall deposits are included in the sample
analysis. Can be combined with a foam insert to collect
the respirable fraction simultaneously.
ADVANTAGES OF THE IOM SAMPLER: CONFORMANCE
The IOM is specified by name in many standards/methods including UK HSE Method 14/3; Australian Standard 3640, and NIOSH Method 5700.
In response to an SKC inquiry, U.S. OSHA issued a statement indicating the IOM could be used as an equivalent sampler for particulates not otherwise classified. Copies available upon request.
OTHER INHALABLE SAMPLERS:BUTTON SAMPLER
Designed for use at
4 L/min to enhance sensitivity
Inlet has a stainless steel inlet screen to keep out large, non-inhalable projectiles from impacting or splashing onto the filter.
Suitable for area or personal sampling. SKC 225-360
SWEDISH MINI-SAMPLER FOR INHALABLE MANGANESE
Enable positioning of the sampler inlet within close proximity of the welder’s nose and mouth even when wearing a face shield.
Used with the SKC Face Level Sampling Head Set
Mini-Sampler SKC 225-6201
Headset SKC 225-6200
Developed in a research project partly funded by the Swedish Work Environment Authority and carried out at Stockholm University, Sweden.
MINI-SAMPLER COMPONENTS
13-mm Swinnex filter holder modified into an open-face filter holder.
Incorporates a specially designed aluminum entry nozzle which protrudes out the front of the holder as the sampler inlet.
PTFE-coated O-ring and the retaining ringholds the 13-mm filter in place in the sampler body.
Figure 1
MINI-SAMPLER:ADVANTAGES/APPLICATIONS
Advantages: The headset mounting
arrangement improves personal sampling as it
maintains the sampler close to nose/mouth.
Applications: Only for inhalable sampling where
90% of the mass size distribution is below 20
um (including manganese).
DATA COMPARISON??TOTAL VS INHALABLE
Inhalable particulate mass is typically greater than so-called 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.
A CONVERSION FACTOR??TOTAL VS INHALABLE
So what do you do? Collect side-by-side
37-mm cassette and inhalable samples and determine process-specific conversion factors for YOUR unique application.
The AIHCE session made the point that it is really not enough to use a simple conversion factor from total to inhalable as there are too many variables.
2013 TLVs®
ISSUED AS INHALABLE
Acrylamide Alachlor Aldrin Asphalt Fume Azinphos-methyl Benomyl Beryllium Borate cpds,
Inorganic Butylated
hydroxytoluene
Calcium sulfate Caprolactam Captan Carbaryl Carbofuran Carbon Black Chlorpyrifos Citral Coumaphos Cresol, all isomers
2013 TLVs®
ISSUED AS INHALABLE Demeton (and Demeton-
S-methyl) Diazinon Dibutyl phosphate 2,2-Dichloropropionic
acid Dichlorvos (DDVP) Dicrotophos Dieldrin Diesel Fuel Diethanolmine Dioxathion
Diquat Disulfoton Endosulfan EPN Ethion 2-Ethylhexanoic acid Fenamiphos Fensulfothion Fenthion Ferbam Flour Dust Fonofos
2013 TLVs®
ISSUED AS INHALABLE Glyoxal Hexahydrophthalic
anhydride Iodine and Iodides Isobutyl nitrite Magnesium oxide Malathion Maleic anhydride 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.
2013 TLVs®
ISSUED AS INHALABLE Nickel Subsulfide 5-Nitro-o-toluidine p,p-Oxybis(benzene
sulfonyl hydrazide) Parathion Particulates Not
Otherwise Specified (now a guideline; not a TLV)
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
2013 TLVs®
ISSUED AS INHALABLE
Tetrethyl pyrophosphate (TEPP)
Thallium 4,4-Thiobis(6-tert-butyl-
m-cresol) Thiram Trichlorphon
Trimellitic anhydride Vanadium pentoxide Wood Dusts Xylidine (mixed
isomers)
2013 INTENDED CHANGES TO TLVs®
ISSUED AS INHALABLE
Clopidol 2,4-D Diethylene glycol
monobutyl ether Manganese, elemental
and inorganic cpds. O-Phthalodinitrile Piperazine and salts 2,4- or 2,6- Toluene
diisocyanate Tributyl phosphate
For TLVs with IFV notation (Inhalable fraction and vapor)
There is no single sampler that can be used.
Requires (2) separate samples: one for each contaminant phase.
THORACIC PARTICULATE:A CLOSER LOOK
Definitions of size fractionSpecifications for samplersSampler optionsApplications
THORACIC PARTICULATEDEFINED
Thoracic particulate is defined as material hazardous when deposited within the lung airways and down into the gas exchange region.
Thoracic samplers have a 50% cut-point of 10 um.
THORACIC SAMPLERSEMERGE
The first thoracic sampler was developed by BGI Inc.
The BGI GK 2.69 cyclone is used with standard 37-mm cassettes at a flowrate of 1.6 L/min.
This sampler is listed in the NIOSH method for metalworking fluids.
THORACIC SAMPLERS:ANOTHER OPTION
SKC offers an impaction based sampler for thoracic particulate called the Parallel Particle Impactor or PPI.
The thoracic PPI is used with any suitable
37-mm filter at a flowrate of 2.0 L/min.
SKC 225-386
U.S. Patent No. 7,073,402
Single-use, disposable model 225-386
PPI OPERATING PRINCIPLE
The disposable PPI looks like a traditional 37-mm filter cassette.
But the inlet section has 4 internal, pre-oiled impactor plates that scrub out larger particles.
The dust size-fraction of interest is collected onto the filter in the outlet section for analysis.
PERFORMANCE OF SKC AND BGI THORACIC SAMPLERS
Aerodynamic Particle Diameter, da, m
Pen
etra
tio
n, P
, %
0
25
50
75
100
GK2.69 (BGI)
Thoracic Convention
0.5 1 5 10 50
Thoracic PPI, QS=2.0 Lpm
THORACIC SAMPLERSCURRENT APPLICATIONS
Thoracic TLVs Sulfuric Acid Cotton Dust
NIOSH Methods NIOSH Method 5524,
for metalworking fluids specifies a
2-um PTFE filter in a
37-mm filter cassette with an optional thoracic particulate sampler.
RESPIRABLE DUST: THE OSHA SILICA NPRM
U.S. OSHA published their
Notice of Proposed Rulemaking (NPRM)
for Occupational Exposure to Respirable
Crystalline Silica in September 2013 .
See this 757-page document at
https://www.osha.gov/silica/nprm.pdf
NOTABLE ISSUE IN THE NPRM:PELs-CURRENT
GENERAL INDUSTRY
A formula based on the % silica in the air sample. Example:
_____10____ % Quartz + 2
PEL is equivalent to 100 ug/m3 when the material is pure quartz . PEL approaches 5 mg/m3, (the PEL for Particulates Not Otherwise Classified) with a low percentage of quartz in the sample.
.
CONSTRUCTION AND
SHIPYARDS
A formula based on obsolete
method of collecting dust into
impingers with analysis by
particle counting.
PEL is approximately
equivalent to 250 ug/m3.
NOTABLE CHANGE IN THE NPRM:PEL-PROPOSED
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)
NOTABLE ISSUE IN THE NPRM:SAMPLER SPECS-CURRENT
Current specs for respirable dust samplers were promulgated in 1971 and are listed in 29 CFR 1910.1000; Table Z-3 for mineral dusts.
Table Z-3 lists the required collection efficiencies of samplers for various particle sizes. Ex. Particles with a diameter of 3.5 um should be collected with 50% efficiency. (50% cut-point) The 25, 75, and 90% cut-points are also listed.
The Dorr-Oliver (nylon) cyclone is the only samplerused by federal OSHA inspectors to meet these specs.
NOTABLE CHANGE IN THE NPRM: SAMPLER SPECS-PROPOSED
Page 539: OSHA acknowledges that the current collection efficiency specs for samplers are obsolete.
Page 542: OSHA states that crystalline silica measurement should be determined by a sampling device designed to meet the characteristics for particle-size-selective samplers specified in ISO 7708:1995 Air Quality-Particle Size Fraction Definitions for Health-Related Sampling.
ISO 7708:1995
This is the standard that ACGIH, NIOSH, CEN, and most countries around the world have already adopted.
The collection efficiency curve for respirable dust samplers in this standard includes a 50% (median) cut-point of 4 um which is more conservative than the existing OSHA specification.
TRADITIONAL SAMPLERS: TO MEET SPECS IN ISO 7708
CYCLONES FROM SKC/FLOWRATES Aluminum Cyclone @ 2.5 L/min-Listed in
NIOSH method. Published journal article .
G(S)-3 Cyclone @ 2.75 L/min-Listed in OSHA NPRM on page 267. Published journal article.
TRADITIONAL SAMPLERS: TO MEET SPECS IN ISO 7708
OTHER CYCLONES /FLOWRATES Dorr-Oliver @ 1.7 L/minListed in NIOSH method and NPRM Higgins-Dewell @ 2.2 L/minEuropean cyclone; Listed in NIOSH method and NPRM BGI GK 2.69 @ 4.2 L/minListed in NPRM
NEW SAMPLER OPTIONS
Page 539: Adoption of this (ISO) definition by
OSHA would allow for workplace sampling to
be conducted using ANY particulate sampling
device that conforms to the ISO definition i.e.
collects dust according to the
particle collection efficiency curve specified in
the ISO standard.
RESPIRABLE PPI SAMPLERS FROM SKC
Specifically designed to precisely match the criteria for respirable samplers specified in the ISO 7708 standard.
SKC RESPIRABLE PPI:FLOWRATE OPTIONS
Single-use, disposable PPI models are available for use at either 2, 4, or 8 L/min.
This provides flexibility in pump options, sample duration, and concentration.
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
PPI DATA:OSHA DOCKET
SKC submitted comments to the OSHA
docket on the silica NPRM with data on
the PPI. (Electronic copies are available). The data which was published in the Journal
of Physics shows that the collection efficiency of
the PPI is a close match to the ISO standard
and the bias is more acceptable than the HD
cyclone (listed in the NPRM.)
MEETING USER DEMANDS:CONVENIENCE
Smaller size-fits under welding helmet or PPE
No assembly of impaction substrates
Pre-loaded with filters or lab loaded like a traditional cassette
No cleaning after sampling
AND FINALLY…
Another disposable size-selective sampler for diesel particulate.
Particulate emissions from diesel exhaust are VERY small particles that rapidly clump together to form particles that are still submicron in size i.e. less than 1 um in aerodynamic diameter.
DPM SAMPLER EMERGES
A single-use, disposable filter cassette for DPM was developed by U.S. NIOSH mining division and the technology was transferred to SKC for commercial production.
SKC 225-317
DPM SAMPLING TRAIN
CycloneRemoves non-respirable particles that may overload the filter
Internal Impactor Plate in CassetteRemoves respirable particles greater than 1.0 um in diameter
Heat-treated Quartz Filter assemblyCollects DPM particles less than 1.0 um in diameter for analysis of elemental carbon (EC).
THANK YOU FROM DUSTY DEBBIE
If you have questions or
need further information,
email me at