Two approaches to convert historical mining dust exposures into respirable fraction based on microscope sizing measurements.
Gao-P; Chen-BT; Zhuang-Z; Hearl-FJ; Schwerha-DJ; McCawley-MA; Soderholm-SC; Chen-W; Chen-J
Chin J Ind Hyg Occup Dis 1999 Jun; 17(3):135-138
In an ongoing epidemiological study to clarify the exposure-response relationship for the development of silicosis in Chinese mine and pottery industries, a large historical data source containing approximately 60,000 mining workers' exposures from 1958 to 1992 was converted into respirable silica mass concentrations. In the original Chinese database, the exposure data were expressed as total mass concentration with size distributions categorized by microscopic sizing. In this report, two options, one by direct calculation using volume contribution in each fraction and the other by using the Hatch-Choate equation, have been developed to convert count fraction into mass fraction. In general, the conversion using the Hatch-Choate equation offered a slightly lower conversion value. The direct calculations using volume contribution in each fraction may be preferable because the assumptions are less restrictive.
Dust-exposure; Mine-workers; Silicosis; Silica-dusts; Respiratory-system-disorders; Pulmonary-system-disorders; Exposure-assessment; Dust-counting; Dust-control; Dust-analysis; Dust-inhalation; Dust-measurement; Dust-particles; Dust-suppression; Dusts; Respirable-dust; Inhalation-studies
Chinese Journal of Industrial Hygiene and Occupational Diseases