Presentation on theme: "INHALABLE PARTICULATE MATTER SAMPLING OPTIONS FROM SKC INC."— Presentation transcript:
INHALABLE PARTICULATE MATTER SAMPLING OPTIONS FROM SKC INC
A GLOBAL DISCONNECT Global differences in definitions of workplace contaminants and standard sampling methods for those contaminants create a variety of problems.
GLOBAL DIFFERENCES IN DEFINTIONS Complicate international comparisons and sharing of data Make our profession seem illogical to lay people including legislators Contribute to differences in worker protection in different countries Complicate the choice of sampling equipment
GLOBAL DIFFERENCES IN SAMPLERS Result in considerable differences in exposure measurements when sampling the same contaminant under identical environmental conditions.
A COMMON SENSE APPROACH Since we are interested in health effects, researchers sought to design a personal sampler that would be based “on a biologically relevant definition of total dust, that is, one which represents the total of what the worker takes in through the nose and/or mouth during the act of breathing”. (Ann. Occup. Hyg. Vol. 30, 1986.)
HISTORICAL EVENTS A Move Toward Standardization ACGIH ISO CEN
HISTORICAL EVENTS In 1982, ACGIH appointed an ad hoc committee on Air Sampling Procedures (ASP) with the task of preparing recommendations for size-selective sampling that would lead to an approach for establishing particle size- selective TLVs for particulates.
HISTORICAL EVENTS In 1983, ISO published Technical Report 7708 giving definitions of particle size fractions corresponding to three regions of the respiratory tract. The fraction which would be measured would depend on the site of action of the particulate material under study.
HISTORICAL EVENTS In 1985, ACGIH published a report with a similar proposal to that published by ISO. In 1987, an ISO Working Group was established to revise TR7708 as an international standard and a CEN Working Group was established to produce a European standard.
HISTORICAL EVENTS In 1993, revisions to Appendix D of the ACGIH TLV booklet, “Particle Size- Selective Sampling Criteria for Airborne Particulate Matter” were adopted by ACGIH. Three particulate mass fractions were defined: inhalable, thoracic and respirable.
HISTORICAL EVENTS U.S. NIOSH nor OSHA have not officially endorsed the three new international particulate definitions in total. The only published method by U.S. government agencies using inhalable samplers is NIOSH 5700 for formaldehyde on dust specifying an IOM sampler or equivalent.
HISTORICAL EVENTS The Health and Safety Executive describes the use of inhalable and respirable samplers that meet the new definitions in MDHS 14/3, “General methods for sampling and gravimetric analysis of respirable and inhalable dust”.
HISTORICAL EVENTS Australia has embraced the new definitions of inhalable and respirable particulate mass in the new drafts of the Australian Standards for sampling and gravimetric determination of inhalable dust (AS 3640) and respirable dust (AS2985).
INHALABLE PARTICULATE MASS Defined as 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.
INHALABLE SAMPLERS Meet the inhalability criterion when a personal sampler mounted on the body gives the same measured dust concentration and aerodynamic size distribution as that inhaled by its wearer, regardless of dust source location and wind conditions. Defined as having a 50% cut-point of 100 microns.
TRADITIONAL FILTER CASSETTES Do not effectively sample inhalable particulate matter They significantly underestimate the concentration of larger dust particles from m. The inlets do not effectively capture the larger particles, particles adhere to the cassette walls and sample loss can occur when removing the filters.
INHALABLE SAMPLERS A personal sampler for inhalable particulate was first developed by Mark and Vincent in 1986 at the Institute of Occupational Medicine and licensed for manufacture by SKC.
IOM SAMPLER ( SKC Cat. No A) Exploded View
USING THE IOM SAMPLER SAMPLE LOGISTICS 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.
USING THE IOM SAMPLER SAMPLE LOGISTICS Place the IOM cassette/filter assembly into the sampler body, screw on the cover cap, and connect to the pump. Calibrate the flow rate to 2 L/min using the IOM Calibration Adapter (Cat. No ) or by placing in a calibration chamber. Following sample collection, weigh the cassette/filter assembly again following the procedures described above.
USING THE IOM SAMPLER SAMPLE LOGISTICS Transport clips are available to transport the filter/cassette assemblies to the sampling site or the laboratory (Cat. No A).
ADVANTAGES OF THE IOM Since the filter and cassette are weighed together, all particles which enter 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.
ADVANTAGES OF THE IOM The collection efficiency gives an acceptable match to the inhalability definition when worn on the lapel as a personal sampler. The performance is relatively independent of wind speed for particles with aerodynamic diameter up to and including 75 m.
WEIGHING ACCURACY OF IOM SAMPLES CONCERNS March/April 1999 AIHA Journal article discusses problems of water absorption by plastic IOM cassette and resulting instability of the tare weight RESPONSE SKC has changed the plastic material to address water. adsorption. Do not desiccate Equilibrate under controlled humidity conditions. Consider stainless steel cassettes.
Studied the use of porous polyurethane foams as size-selectors Placed in the inlet of the IOM sampler Allow for the collection of inhalable and respirable sub fraction using existing IOM samplers Followed by gravimetric analysis Used for a variety of particulates including bioaerosols NEW IOM RESEARCH BY U.K. HEALTH AND SAFETY LABORATORY
IOM SAMPLER WITH MULTIDUST FOAM DISCS Inhalable Respirable UNDER STUDY Thoracic PM10 Combination discs New Cassette with Elongated Inlet Required
PUBLICATIONS ON IOM BY HSE LAB HSE Lab Publication on Foam Discs, Project Leader: L C Kenny Journal of Aerosol Science, Vol. 30, No. 5, pp , 1999 on sampling efficiency with low air movement AIHA Journal, Vol. 59, pp , 1998 on sampling with foams for bioaerosols Methods for the Determination of Hazardous Substances 14, Health and Safety Executive, January 1997
NEW INHALABLE RESEARCH BY UNIV OF CINCINNATI Button Sampler - Alternative to the IOM sampler for inhalable dust Inlet is formed from a spherical shell with numerous, evenly spaced holes Holes act as orifices and provide multidirectional sampling capabilities Cat. No
USING THE BUTTON SAMPLER SAMPLE LOGISTICS Unscrew the sampler inlet and remove the PTFE O-ring. Place a 25-mm filter on the stainless steel support screen, replace the 0-ring and the sampler inlet. A filter pore size of 1.0 m or higher is recommended due to the backpressure limitations of personal samplers.
USING THE BUTTON SAMPLER SAMPLE LOGISTICS Calibrate the Button Sampler to a flowrate of 4 L/min using the calibration adapter (Cat. No ) or by placing in a calibration chamber. After sampling, remove the filter for analysis. SKC offers a conductive plastic filter transport case for shipment to the lab. (Cat. No )
ADVANTAGES OF BUTTON SAMPLER Closed-face inlet keeps out large particles 25-mm filter directly behind inlet avoids transmission losses in sampler Uniform distribution of holes minimizes sensitivity to wind velocity and direction Flow rate of 4 L/min for personal sampling increases sensitivity Can be used for personal or area sampling
PUBLICATIONS ON BUTTON SAMPLER BY UNIV OF CINCINNATI AIHA Journal, Vol. 61, , 2000 on performance characteristics Aerosol Science and Technology, Vol. 28, , 1998 on effects of wind velocity and direction AIHA Journal, Vol. 58, , 1997 on field testing of sampler Atmospheric Environment, Vol. 29, No. 10, pp , 1995 on design of prototype
CONCLUSIONS REPORTED For the Button Personal Sampler Effects of wind direction: No significant effects Effects of wind velocity: Lower than for IOM, GSP and 37-mm cassette Accuracy (direction- averaged): Better an 37-mm cassette, comparable to GSP, lower than IOM Precision (direction- specific): Equal or better than IOM, GSP, or 37-mm cassette
ABRASIVE BLASTING A NIOSH Health Hazard Evaluation indicated that current methods do not provide reliable measurements of worker exposure to lead and other contaminants during abrasive blasting in small confined spaces.
ABRASIVE BLASTING Current sampling methods using 37-mm cassettes often grossly overestimate exposure to very large, noninhalable particulate. In NIOSH HHEs, nearly all of the lead in the samples was due to grit that entered the cassettes due to rebound of grit in confined spaces.
JOURNAL ARTICLE APPLIED OCCUPATIONAL AND ENVIRONMENTAL HYGIENE, Vol. 15, p , 2000 on use of Button Sampler with screen for evaluating metal exposures among abrasive blasting workers at four US Air Force Facilities
OTHER INHALABLE SAMPLERS 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.
INHALABLE TLVs 2010 INTENDED CHANGES Carbon black Maleic anhydride Manganese (elemental and inorganic cpds., as Mn) Piperazine 4,4-Thiobis (6-tert-butyl- m-cresol) Toluene 2,4- or 2,6- diisocyanate (or as a mixture)
DATA CONVERSION?? TOTAL TO INHALABLE Aerosol Classification and Conversion Factor -Dust2.5 -Mist2.0 -Foundries1.5 -Welding1.0 -Smokes/fumes1.0 Published by Werner et. al. in the Analyst, 121:1207
THE FUTURE OF SIZE- SELECTIVE SAMPLING More inhalable TLVs New thoracic TLVs Development of thoracic samplers Enhanced use of foams as pre- selectors