Relationships between inhalable, thoracic, and respirable aerosols of metalworking fluids.

The aim of the study described in this companion paper was to assesses relationships among inhalable, thoracic, and respirable aerosol fractions of metalworking fluids. A RespiCon sampler, which simultaneously collects all three fractions, was used at four Ontario plants to collect 37 samples of 120 to 400 min duration. The ratios of the slopes of the lines of a regression model forced through the origin between inhalable and thoracic, inhalable and respirable, and thoracic and respirable were 1.38, 1.51, and 1.13, respectively. These ratios would be useful in assessing metalworking fluid airborne exposure data based on different aerosol fractions and for interpreting occupational exposure standards based on different fractions.