[Estimation of the indoor diffusion of asbestos fibers with the Pasquill and Gifford diffusion model for the external environment]

Stima della diffusione indoor di fibre di amianto con il modello diffusionale di Pasquill e Gifford per l’ambiente esterno

In absence of results of environmental monitoring to proceed with the assessment of occupational exposure, it was developed a model that retraces the one of Pasquill and Gifford, currently used for the estimation of concentrations of pollutants at certain distances from the source in outdoor environment. Purpose of the study is the quantitative estimate of the diffusion of airborne asbestos fibers in function of the distance from the source in an factory where railway carriages were produced during the period when asbestos was sprayed as insulator of the body. The treatment was carried out in a large shed without separation from other operations. The application of the model, given the characteristics of the emitting source, has allowed us to estimate the diffusion of particles inside the shed with an expected decrease in concentration inversely proportional to the distance from the source. By appropriate calculations the concentration by weight has been converted into number of fibers by volume, the unit of measure currently used for the definition of asbestos pollution.