Abstract
Size selective samplers used in estimating potential inhalation hazard to the worker collect particles according to their aerodynamic size. Calibration of these samplers are generally performed under low humidity conditions even though they may be required to operate in a high humidity atmosphere. A series of experiments using iron oxide and Polystyrene Latex (PSL) aerosols were performed to determine differences in aerodynamic size measured in dry and humid atmospheres. The LASL Spiral Centrifuge Aerosol Spectrometer and a horizontal elutriator were used to measure the differences in aerodynamic size (Dae). Under constant temperature conditions there is no change in Dae for particles as small as 0.312 μm for relative humidities as high as 97%. However, the combination of slight temperature decreases and a humid environment leads to significant changes nil Dae.