A study was carried out among iron foundry workers to assess occupational exposure to ambient respiratory dust in their work environment and rates of risk factors in each process using Bayesian decision analysis (BDA) and AIHA (American Industrial Hygiene Association) exposure categorization guidelines. A total of 93 respirable dust samples were collected in various processes, including the molding, melting, shake-out, heat treatment, felting and finishing units of the foundries. The mean concentrations of respirable dust were 1.40±0.86 mg/m3 in the molding process, 1.42±0.63 mg/m3 in melting, 0.56±0.59 mg/m3 in shake-outs, 1.63±0.85 mg/m3 in heat treatment, 2.17±0.61 mg/m3 in felting and 3.30±3.47 mg/m3 in the finishing sections, respectively. The mean levels of respirable dust in the finishing process exceeded the ACGIH standard (TLV 3.0 mg/m3). The results of BDA showed that the respirable dust exposures were in AIHA category 4 for shake-outs (96.7% probability), felting (98.1% probability) and finishing (100% probability), respectively. The exposures belonged to category 3 for molding (52.8% probability), melting (79.4% probability) and heat treatment (40.3% probability), respectively. Therefore, it is required to have immediate control and safety adaptation by personal protective equipment of proper respiratory musk, engineer control, chemical analysis of respirable dust, exposure surveillance in order to prevent from being exposed to respirable dust among the foundry workers.

Key words: Dust exposure, foundry, Bayesian model and risk factor.

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