Respiratory Deposition and Occupational Exposure to Particulate Matter in Stone Carving: Insights from Real-Time Mass and Number Concentrations

Rising cases of silicosis among stone carvers highlight the urgent need to assess occupational particulate matter (PM) exposure. Health impacts and personal exposure in stone-related industries, especially in controlled environments, have been studied previously. However, real-time particle size distribution with respiratory deposition analysis has remained largely unexplored. This study bridges this gap by analyzing both particle mass concentrations (PMCs) and particle number counts (PNCs) across multiple size fractions of PM at an active stone carving site. This study aims to characterize workplace PM emissions and evaluate the respiratory deposition fraction in the lungs of workers. It integrates size-segregated exposure across four size bins, 0.253–1.0, 1–2.5, 2.5–4, and 4–10 µm, to estimate regional deposition in the respiratory tract, thus providing a more comprehensive assessment of health risks in stone carvers. Real-time PMC and PNC were measured using GRIMM EDM264, during a monitoring campaign at an active stone carving site and background location (BGL). The multiple-path particle dosimetry and the International Commission on Radiological Protection models were applied to estimate PM deposition in different regions of the lung. The average PM10, PM4, PM2.5, and PM1 concentrations were about 11, 6, 5, and 2.5 times higher, respectively, than BGL levels, indicating significant exposure. Lung-deposited mass is significantly higher than in ambient air studies, with site levels exceeding background by 60%–90%. Among the different size fractions, PM4 exhibited the highest deposition in the tracheobronchial region, while PM2.5 showed the greatest deposition in the left lower lobe. This study is the first to comprehensively assess size-segregated PM emissions and respiratory deposition in the stone carving industry, revealing substantial occupational exposure. The findings emphasize the urgent need for workplace interventions and enhanced respiratory protection to mitigate health risks.