Levels of atmospheric pollution by man-made mineral fibres in buildings.

: The widespread use of man-made mineral fibres (MMMF) as insulation products in buildings can be a potential source of indoor pollution, but few data are available. Pollution levels were determined at 79 indoor and 18 outdoor locations. The standardized method (membrane filter method) was adapted to the environmental settings: 10 m3 of air was sampled over a period of 5 days; the specimen was prepared by an indirect method (low-temperature ashing); counting was carried out at a magnification of 250; MMMF were identified by their optical properties under the polarizing optical microscope. Indoor pollution levels were found to be in the range 0-6230 respirable fibres per m3, with a median value of 3. Outdoor airborne pollution levels were lower than 15 respirable fibres per m3, with a median value of 1. More data are needed in order to make a more precise assessment of the risk associated with environmental MMMF pollution; a standardized method of obtaining such data is also necessary.