New methods for quantitative respirator fit testing with aerosols

Abstract

Quantitative respirator fit testing is generally performed by measuring the concentration of DOP aerosol leaking into the breathing space between the respirator and the wearer's face. In the conventional technique, the concentrations inside and outside the mask are determined photometrically through measurements of the scattered light intensities from the DOP clouds. DOP, however, has recently been implicated as a potential human carcinogen. We have adapted a continuous-flow condensation nuclei counter (CNC) for fit testing and have been able to use a variety of non-hazardous test aerosols which are not measurable by the conventional technique. The CNC enlarges submicrometer-sized particles into the light scattering range, so virtually any fine particle cloud can be used for fit testing. Comparison tests between photometer and CNC measurements show the utility of the new technique. The potential use of an aerosol electrometer is also discussed.