evaluation of workers’ exposure to metalworking fluid (mwf) mist factors affecting its dispersion in an automobile manufacturing factory

introduction: metalworking fluids (mwfs) are widely used in metal working operations for cooling down, lubricating and reducing the friction between tools and work pieces which result in controlling the heat produced. exposure to mwfs causes several adverse effects including respiratory problems, skin diseases, cancer and even infertility. this study examines workers’ exposure to mwf mist and the factors affecting the dispersion of it in an automobile factory. materials and methods: this cross-sectional study was carried out in metal working units (producing cylinder and cylinder head) of an automobile manufacturing factory during two seasons of spring and summer.  from the total of 300 people working in the factory 75 workers were randomly selected. 38 workers were tested for total particulate status and 37 for the thoracic particulate status. the mwf used in unites was soluble. using niosh 5524 method, sampling and exposure evaluation was carried out with personal air sampling pump, closed-faced 37-mm cassette, 37-mm diameter 2-µm pore size teflon and personal cyclone. thermal anemometer was used to measure the air temperature and air velocity. data were analyzed using t, mann withney, anova, regression, pearson correlation coeficent tests. results: the mean of workers exposure to total and thoracic dust were 2.65 ± 1.3 and 1.64 ± 0.95 mg/m3 respectively. the above values for mwf mists were 2.19 ± 0.92 and 1.28 ± 0.88 mg/m3 respectively. the results indicated a higher exposure to mwf mists in terimery workplace than that of donobat and terimery cylinder head (p<0.05). temperature had positive effect on mwf mists dispersion (p<0.05). conclusion: all exposure levels were under the threshold limit value level (tlv-twa, pel = 5 mg/m3). however, they were well above the niosh recommend exposure level (rel = 0.5 mg/m3). the result showed that air temperature is an important factor in increasing mwf mists production and dispersion (r= 0.572).