Variability in total dust exposure in a cement factory.

Exposure assessment is a main component of epidemiologic studies and variability in exposure. This assessment is considered as a common approach for such phenomenon. A total of 129 dust samples were collected randomly from 197 personnel from a cement factory located in Ilam province, during 2009 in Iran. The between- and within-group components of variability were determined to assess the contrast in exposure level between the Similar Exposure Groups (SEGs) and to calculate the within-worker geometric standard deviation of the theoretical exposure-response slope. Results were analyzing by one-way random effects model. According to the mentioned model, the probability of long-term mean exposure exceeding to the occupational exposure limit (OEL) was assessed for each SEGs. The arithmetic means (AM) of total dust levels ranged from 0.04 to 39.37 mg/m(3). The geometric means (GM) of total dust were higher in the crusher (20.84 mg/m(3)), packing (17.29 mg/m(3)), kiln (16.78 mg/m(3)), cement mill (14.90 mg/m(3)), and raw mill (10.44 mg/m(3)). However, the figures for the maintenance and administration parts were 3.77 mg/m(3) and 1.01 mg/m(3), respectively. The random effects model data demonstrated that the F-value calculated was greater than the critical F-value approximately 59% of the variability in the exposure was due to differences between groups. Based on these finding, the order of probability of the long-term mean exposure exceeding (Z) to the OEL of 10 mg/m(3) for total dust which were in kiln (100%), packing (100%), cement mill (90%), crusher (73%), raw mill (60%) administration (2.3%) and the maintenance parts (0%).