Present procedures in quantitative respirator fit testing: problems and potential solutions.
Appl Occup Environ Hyg 1990 Nov; 5(11):762-765
Issues related to quantitative respirator fit testing were discussed and the role of respirators in industrial hygiene was summarized. Respirators were used to prevent inhalation of contaminated air in environments where engineering controls cannot reduce the concentration of the contaminants to acceptable levels. The type of respirator used has been dependent on the nature of the respiratory hazard. The respirator selected was expected to give at least a minimum fit to the face of the wearer, with the minimum fit specified by federal regulations. Respirator fit has been determined by either qualitative or quantitative methods. When quantitative methods were used, respirator fit factors, defined as the ratio of a test agent outside the respirator to its concentration inside the respirator, were measured individually for each wearer. Current procedures for determining fit factors and problems associated with quantitative respirator fit testing were discussed. Most problems have stemmed from sampling biases resulting from inadequate mixing of the test aerosol with air, inequalities in flow distribution occurring during inhalation or exhalation, and variations in leakage flow due to unregulated head movements occurring during testing. Possible solutions included breath holding at a sample flow rate comparable to the instantaneous inhalation flow rate and performing fit tests in specific head positions. Measuring face seal leakage was discussed. It was noted that current fit testing procedures do not evaluate the degree of protection offered by a respirator. They measure only the degree of fit of a certain respirator to a specific face. The authors conclude that face seal leak testing that includes breath holding and testing in specific head positions can give more accurate results than the current tests.
NIOSH-Publication; NIOSH-Grant; Respiratory-protective-equipment; Industrial-hygiene; Air-flow; Statistical-analysis; Anthropometry; Health-protection; Leak-prevention
Environmental Health University of Cincinnati Dept of Environmental Health Cincinnati, Ohio 45267
Applied Occupational and Environmental Hygiene
University of Cincinnati, Cincinnati, Ohio