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Prototype sampling system for measuring workplace protection factors for gases and vapors.

Authors
Groves-WA; Reynolds-SJ
Source
Appl Occup Environ Hyg 2003 May; 18(5):394-402
NIOSHTIC No.
20024325
Abstract
A prototype sampling system for measuring respirator workplace protection factors (WPFs) was developed. Methods for measuring the concentration of contaminants inside respirators have previously been described; however, these studies have typically involved continuous sampling of aerosols. Our work focuses on developing an intermittent sampling system designed to measure the concentration of gases and vapors during inspiration. This approach addresses two potential problems associated with continuous sampling: biased results due to lower contaminant concentrations and high humidity in exhaled air. The system consists of a pressure transducer circuit designed to activate a pair of personal sampling pumps during inspiration based on differential pressure inside the respirator. One pump draws air from inside the respirator while the second samples the ambient air. Solid granular adsorbent tubes are used to trap the contaminants, making the approach applicable to a large number of gases and vapors. Laboratory testing was performed using a respirator mounted on a headform connected to a breathing machine producing a sinusoidal flow pattern with an average flow rate of 20 L/min and a period of 3 seconds. The sampling system was adjusted to activate the pumps when the pressure inside the respirator was less than -0.1 inch H(2)O. Quantitative fit-tests using human subjects were conducted to evaluate the effect of the sampling system on respirator performance. A total of 299 fit-tests were completed for two different types of respirators (half- and full-facepiece) from two different manufacturers (MSA and North). Statistical tests showed no significant differences between mean fit factors for respirators equipped with the sampling system versus unmodified respirators. Field testing of the prototype sampling system was performed in livestock production facilities and estimates of WPFs for ammonia were obtained. Results demonstrate the feasibility of this approach and will be used in developing improved instrumentation for measuring WPFs.
Keywords
Workplace-monitoring; Workplace-studies; Vapors; Gases; Sampling-methods; Respirators; Respiratory-equipment; Respiratory-protective-equipment; Personal-protective-equipment; Air-contamination
CODEN
AOEHE9
Publication Date
20030501
Document Type
Journal Article
Funding Amount
108000
Funding Type
Grant
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-K01-OH-000177
Issue of Publication
5
ISSN
1047-322X
Source Name
Applied Occupational and Environmental Hygiene
State
PA; CO
Performing Organization
Penn State University, University Park, Pennsylvania
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