Raman spectroscopy and X‐ray diffraction responses when measuring health‐related micrometre and nanometre particle size fractions of crystalline quartz and the measurement of quartz in dust samples from the cutting and polishing of natural and artificial stones

Abstract: Around 560 000 workers in Great Britain are potentially exposed to respirable crystalline silica (RCS), which can cause disabling diseases, such as silicosis and lung cancer. These experiments assessed the performance of a new Raman spectroscopy method for measuring RCS, in samples of pure quartz powder with different median aerodynamic particle diameters and stone dusts from variety of natural and artificial stones. The relationship between the Raman response and particle size was characterised by measuring subfractions of the respirable quartz standard A9950 collected using the Sioutas impactor. Bulk samples of quartz standards A9950 and Quin B that provided the highest median particle size diameters were also measured. Health‐related thoracic and respirable particle size fractions, and the environmental monitoring fractions of PM10, PM2.5, PM1 and PM0.5, were also collected during the powered cutting and polishing of sandstone and diorite (granite), engineered and sintered stones. All Raman spectroscopy results were compared with those from X‐ray diffraction (XRD), which was used as the reference technique. The Raman spectroscopy response closely followed the predicted crystallinity of RCS for different particle diameters. Raman spectroscopy obtained slightly higher percentages than XRD for particle size fractions below 1 μm. The Raman spectroscopy and XRD results were highly correlated for the thoracic, respirable and impactor fractions. The coefficients of determination were between 0.98 and 0.95. The slope coefficients for the correlation were 1.11 for the respirable fraction and 1.07 for the thoracic fraction. Raman spectroscopy is a promising alternative to XRD for measurement of RCS with a much lower limit of detection of 0.21 μg compared with 1 μg.

What is it about?

The study compares the performance of Raman spectroscopy and X-ray diffraction (XRD) for measuring respirable crystalline silica (RCS) in samples of pure quartz powder and stone dusts from various natural and artificial stones. Raman spectroscopy showed a lower limit of detection (LOD) of 0.21 μg compared to XRD's 1 μg. The two techniques were highly correlated for the health-related thoracic and respirable particle size fractions, with coefficients of determination between 0.98 and 0.95. Raman spectroscopy is a promising alternative to XRD for measuring RCS, particularly in samples containing significant levels of zircon.

Why is it important?

This research is important because it presents a new method for measuring respirable crystalline silica (RCS), a harmful substance that can cause diseases like silicosis and lung cancer. The study compares the performance of Raman spectroscopy with the reference technique of X-ray diffraction (XRD) and shows that Raman spectroscopy is a promising alternative to XRD for measuring RCS with a much lower limit of detection. This is significant because there are around 560,000 workers in Great Britain who are potentially exposed to RCS, and accurate measurement is essential for assessing and controlling exposure levels in the workplace.

Key Takeaways:

1. Raman spectroscopy is a promising alternative to XRD for measuring RCS with a lower limit of detection.

2. Raman spectroscopy is highly correlated with XRD when measuring health-related particle size fractions of aerosols generated from the cutting and polishing of natural and artificial stones.

3. Raman spectroscopy has a distinct advantage over XRD when measuring crystalline silica in samples containing significant levels of zircon.