Characterization of Crystalline Silica Polymorphs by Infrared Spectroscopy

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Crystalline silica (such as quartz) is often present in occupational environments where mining, manufacturing and construction are performed. It is estimated that at least 1.7 million North American workers are potentially exposed to respirable dust of crystalline silica. Such exposure is associated with the development of often-fatal lung diseases including silicosis and lung cancer. Efficient sampling and quantification of silica dust is thus important to ensure a safe working environment that respects the occupational exposure limit. Sampling in the workplace consists of drawing air through a cyclone onto a filter cassette to trap respirable dust followed by quantification by infrared spectroscopy or X-ray diffraction. Many laboratories, OSHTECH included, employ a transmission infrared method that has various advantages but that requires cumbersome sample preparation. This project aims to develop a simplified analytical protocol for the quantification of crystalline silica by infrared spectroscopy. We will explore a series of alternative infrared techniques to accurately quantify crystalline silica without multistep preparation and manipulation of the currently applied method. We will conduct measurements using methods such as transmission, diffuse reflection, attenuated total reflection, and photoacoustic infrared spectroscopy. Our ultimate objective is to develop a non-destructive method with a detection limit equal to or even better than that of existing methods. A successful project will help hygiene professionals and regulators to better protect Canadian workers.