Sampling, analysis, identification and monitoring of fibrous dusts and aerosols

Abstract

Fibrous dusts and aerosols, consisting of asbestos and natural and man-made mineral fibres, whether dispersed in workplace environments or in the indoor and outdoor atmosphere, are toxic and carcinogenic. Their measurement in air and their personal dosimetry are necessary. Optical microscopy and phase-contrast optical microscopy are used as standard procedures for the approximate determination of fibrous dust concentrations in workplace environments. The methods with the best available technology and the methods of choice are scanning electron microscopy (SEM) and transmission electron microscopy. These are applied for sensitive and specific detection and measurements. Two standard reference procedures can be applied for the direct evaluation of filter samples. Fibrous aerosols of all particle sizes and types can be quantitatively evaluated and qualitatively identified by combination of these procedures (SEM is used as a high-quality screening test). Concentrations as low as 100 fibres m^–3 are measurable. The existing on-line and real-time monitoring methods are based on the light-scattering principles. Some commercially available equipment is described and critically evaluated. The capabilities, accuracy, sensitivity and detection limits of all the methods mentioned and their comparison are presented and discussed. The health risk evaluation of measured values can be realized by application of toxic and carcinogenic models.