Abstract:
Air-purifying respirators are commonly used for protection from hazardous atmospheres. Leakage through the respirator faceseal is a major source of exposure. Quantitative fit testing evaluates this leakage by exposing the respirator wearer to known challenge agent concentrations. The ratio of the challenge concentration outside the respirator to the concentration inside the facepiece provides a quantitative index of respirator performance.
Oil aerosols or other particulates are standard challenge agents. It has not been unequivocally shown that testing with an aerosol agent adequately predicts performance under a gaseous challenge. The goal of this project was to compare gas and aerosol leakage into half-face air-purifying respirators. A close correlation in penetration between the two agents would increase confidence that testing with aerosols also predicts performance against gases and vapors.
Corn oil aerosol and FreonR-12 were chosen as challenge agents. Subjects used half-face respirators equipped with combination HEPA and organic vapor cartridges. They performed a standard protocol of exercises inside the exposure chamber. A strong correlation was observed between measured gas and aerosol concentrations inside the facepiece.