Size and shape particle analysis by applying image analysis and laser diffraction – Inhalable dust in a dental laboratory

This paper focuses on particle characterisation using two different methodologies – laser diffraction and image analysis based on scanning electron microscopy. The experimental part of the research was conducted in a dental laboratory, using a personal sampler for dust sample acquisition. Within the image analysis, two parameters of particle size analysis were applied: MeanFeret’s diameter and an equivalent circle diameter. The particle shape is evaluated with respect to three factors: convexity, elongation, and circularity. The obtained particle size distribution, for both methods, showed that the majority of particles were respirable. In addition, the application of the energy dispersive X-ray spectroscopy method showed the presence of several hazardous substances in the workplace. Spearman’s rank correlation coefficients were calculated to determine how shape factors and particle size were related.