Assessment of bagging operators exposure to with pvc airborne particulates
The hazard potential of airborne particles is dependent on the mass concentration as well as the particle size. Particle size determines the deposition site within the respiratory tract and the subsequent health effects. Particle-size is considered from two viewpoints: The sizefraction most closely associated with the specific health effect, and the mass concentration within that size fraction. Polyvinyl chloride (PVC) is one of the most widely used plastic materials (Lewis, 1999). At the end of the PVC synthesis process, the material may exist as an airborne dust includes total or repirable particulates. Szende et al., (1970) first suggested that exposure to PVC dust might cause pulmonary abnormalities similar to pneumoconiosis. They diagnosed advanced pneumoconiosis in a 31 year old man who had been exposed to high concentrations of PVC dust for 12 months and developed severe respiratory failure. A number of studies (Lilis et al., 1975; 1976; Soutar et al., 1980; Mastrangelo et al., 1981; Ng et al., 1991; Lee et al., 1991) showed that impairment of lung function and higher prevalence of small opacities on chest X-ray were associated with PVC dust exposure. These changes were more pronounced in individuals with longer exposures. However, the risk factors and the mechanisms of this impairment are still unclear. The prognosis of pulmonary changes caused by PVC dust differs in different reports. For instance, a patient with reduced lung function and fine nodular opacities in both lower lobes, as evidenced by high resolution computed tomography (HRCT), after 8 year PVC exposure, had an improved pulmonary function 3 months after cessation of exposure; both lung function and HRCT improved further 1 year later (White and Ehrlich, 1997).