Published by Oxford University Press doi:10.1093/annhyg/meh042 Determinants of Exposure to Metalworking Fluid Aerosol in Small Machine Shops

The purpose of this study was to evaluate personal exposure to metalworking fluid (MWF) aerosols in very small machine shops (1–8 machinists per shop) and to investigate workplace factors associated with exposures. A total of 20 willing machine shops in Vancouver, Canada (from 46 eligible shops, 43%) and 88 machinists participated (participation rate for machinists 92%). Most machinists wore two personal sampling trains (an open-faced 37 mm cassette and a PM10 impactor) on each of two full work shifts. Observational data were collected regarding potential determinants of exposure at 15 min intervals throughout each shift. A total of 322 personal samples were taken over 54 days. Mean aerosol exposure was 0.32 mg/m3 (range 0.06–2.19) for the 37 mm cassette samples and 0.27 mg/m3 (range 0.026–3.67) for PM10. Expos-ures from the two sampler types were highly correlated (R = 0.86). The mean shop-specific ratio comparing exposure from the 37 mm cassette with that from the PM10 sampler was 1.43 and varied significantly across shops, ranging from 0.97 to 2.19. Machine, task and shop character-istics associated with significantly increased aerosol exposure included the proportion of time spent grinding, operating an enclosed computer controlled machine, the presence of welding in the shop for both sampler types and the number of machines using MWF for PM10 sample