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Published on: February 14, 2019
Gaseous contaminant distribution in the breathing zone
1National Institute of Occupational Safety and Health, Japan. ojima@h.jniosh.go.jp
Industrial Health
|July 14, 2012
Summary
Worker exposure to ethanol vapor is not uniform within the breathing zone. Measurements show nose concentration is significantly lower than chest concentration, especially for mannequins, highlighting the need for accurate exposure assessment.
Area of Science:
- Occupational Health and Safety
- Industrial Hygiene
- Environmental Science
Background:
- The conventional definition of the breathing zone assumes homogeneous contaminant concentration.
- Recent studies suggest non-uniform contaminant distribution within the breathing zone, particularly near sources.
Purpose of the Study:
- To investigate the spatial variability of contaminant concentrations within a worker's breathing zone.
- To compare personal exposure measurements at different sampling points (nose vs. chest).
- To assess the influence of sampling location and body temperature on exposure levels.
Main Methods:
- Comparative personal exposure measurements were conducted in a laboratory setting.
- Ethanol vapor was released in front of a human subject and a mannequin.
- Vapor concentrations were measured simultaneously at the nose and chest sampling points.
Main Results:
- The ratio of nose concentration to chest concentration was 0-0.2 for the human subject and 0.12 for the mannequin.
- Mannequin exposure levels were 5.5 to 9.3 times higher than those of the human subject.
- Significant spatial variability in contaminant concentration within the breathing zone was observed.
Conclusions:
- The assumption of homogeneous contaminant concentration in the breathing zone is questionable.
- Sampling location significantly impacts measured exposure levels.
- Further research is needed to refine breathing zone monitoring techniques for accurate worker exposure assessment.
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