Airborne Crocidolite Asbestos Fibers in Indoor and Outdoor Air in a Rural Area, China

Forty-eight air samples were collected in a rural area of China. The concentrations of asbestos fibers in the samples were determined by phase contrast microscopy and scanning electron microscopy in combination with energy-dispersion X-ray analysis. The mean concentrations of asbestos fibers in indoor and outdoor air samples were 0.0038 and 0.0037 f/mL, respectively. The fiber concentration was higher in areas in which outcrop crocidolite asbestos is present in the soil than in areas lacking this feature. Airborne asbestos fibers in the study area might be attributable to the weathering of natural outcrop crocidolite asbestos and the impact of human activities on crocidolite asbestos-containing soils. About 50% of the total asbestos fibers in both indoor and outdoor air samples were >= 5 to >= 10 mu m long. Scanning electron microscopy showed that the crocidolite asbestos fibers were mostly thinner than 0.25 mu m. At present, asbestos-containing soils are rarely used to produce asbestos stoves, pave roads, construct houses, or paint walls. However, asbestos fibers are continuously released into the air from these soils, due to natural weathering and human activities, and local residents are thus exposed to asbestos fibers throughout their lifetimes, and thus their health might be adversely affected by long-term inhalation of the fibers.