Protocol for the determination of personal exposure to airborne natural asbestos fibers in the workplace of ornamental stones

  • Patrizia Santucciu INAIL Dir. Regionale Lombardia - Consulenza Tecnica Accertamento Rischi e Prevenzione, Corso di Porta Nuova, 19 - 20121 Milano, Italy; Ph. ++39 02 62586521; Fax. ++39 02 62586004, e-mail: p.santucciu@inail.it
  • Anna Somigliana Agenzia Regionale per la Protezione dell’Ambiente della Lombardia - Settore laboratori, Centro di Microscopia Elettronica
Keywords: Natural asbestos, Green Stones, occupational exposure

Abstract

The term “natural occurring asbestos†(NOA) refers to the mineral as a natural component of soils or rocks, with a mineral
content variable and not predictable quantitatively (Pietre Verdi), as opposed to asbestos in commercial products,
mining or processing operations. Naturally occurring asbestos can be released from rocks in quarries and in manufacturing
laboratories. In Italy the NOA is present in various situations over the national territory, among these the “Serpentino
della Valmalenco†(“massive†and schistose commercial varieties), derived from the Malenco massif (Central Alps,
Sondrio) is a well known serpentinitic stone. The morphological characteristics of the fibers of natural asbestos released
in quarries and in processing laboratories of the Pietre Verdi of the Valmalenco, had required the development of a tailored
protocol of sampling and analysis for the evaluation of occupational airborne exposure. The critical factors in airborne
asbestos evaluation were the correct dust amount on the filters (depending on quarrying or processing activity)
and the distinction between chrysotile asbestos and fibrous antigorite splinters. The protocol is described in detail in all
of its phases: sampling preparation, air sampling, filter preparation, analysis, measurement uncertainty and test report.
The protocol requires the use of Scanning Electron Microscopy equipped with X rays microanalysis of fluorescence for
quantification and identification of asbestos fibers.

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