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Aerosol penetration through respirator exhalation valves
1UCLA Occupational Health Center, Department of Environmental Health Sciences, School of Public Health 90024.
American Industrial Hygiene Association Journal
|October 1, 1990
Summary
Industrial respirator exhalation valves can fail due to dirt or damage, allowing significant aerosol penetration. Even small amounts of contamination or damage compromise respirator effectiveness.
Area of Science:
- Occupational Health and Safety
- Industrial Hygiene
- Respiratory Protection
Background:
- Exhalation valves are essential respirator components controlling inward contaminant leakage and exhalation resistance.
- These valves are vulnerable to dirt and damage, potentially compromising respirator integrity.
Purpose of the Study:
- To quantify aerosol penetration through compromised industrial respirator exhalation valves.
- To assess the impact of valve seat contamination and damage on respirator performance.
Main Methods:
- Aerosol penetration was measured using normal and compromised exhalation valves.
- Compromises included simulated dirt/paint contamination and fine copper wires of varying diameters on the valve seat.
- Penetration was evaluated under different work rates and varying aerosol particle sizes.
Main Results:
- Compromised valves, whether by paint, dirt, or wires (≥250 microns), showed significant aerosol penetration (>1%).
- Penetration increased with wire diameter and was comparable to dirt/paint contamination.
- Work rate had minimal effect on penetration, while larger particle sizes significantly reduced it.
Conclusions:
- Exhalation valve contamination or damage can lead to substantial inward aerosol leakage in respirators.
- Visual inspection under good lighting is crucial for identifying compromised valves and ensuring respirator safety.
- Maintaining clean and undamaged exhalation valves is critical for effective respiratory protection.