Worker exposure to airborne particles in industrial settings: evaluation of exposure assessment and modelling tool

[eng] Exposure to particulate matter in work environments has been linked to ischemic heart, cardiovascular and respiratory-related disease risk increase due to inhalation. Increased adverse health effects have been linked to nanoparticles (< 100 nm) due to their ability to reach the deepest sections of the respiratory tract and their longer retention time. Exposure monitoring is widely used method to assess worker exposure to airborne particles. However, other prediction tools have been explored such as the use of the dustiness index, mass-balance models, and health risk assessment tools. Discussions regarding the use and application of the latter tools are ongoing due to their relatively novelty for worker exposure assessment, the need to test their performance under real- world scenarios, and the need to understand the uncertainties related to critical parameters and limitations. The main objectives of this PhD Thesis are to 1) assess worker exposure to particles (4 nm - 35 μm) in ceramic industry real-world workplace scenarios; 2) evaluate currently used exposure assessment metrics and decision-making approaches; 3) understand the relationship between material dustiness and worker exposure; 4) evaluate the performance of mass-balance models, and 5) compare health risk assessment tools. Worker exposure was assessed during mechanical handling of powders in 6 different scenarios and for 15 materials as well as thermal spraying of ceramic coatings. Exposure monitoring was conducted using online and offline instruments which allowed for the characterization of particle mass and number concentrations, particle size and size distribution, particle morphology and chemical composition. In addition, some of these scenarios were also selected to assess relationship between the dustiness index and exposure concentrations as well as the ability of different particle metrics to represent worker exposure. Finally, decision making approaches, and the performance of mass- balance models and risk assessment tools were tested. Results evidenced clear impacts of industrial activities on workplace exposure to coarse, fine and nanoparticles. Significant increases of inhalable and respirable particle mass concentrations (inhalable mass concentration 80-4000 μg m-3) were observed during mechanical handling of raw materials (d50 2.7-40 µm), when compared to background concentrations. The highest mean inhalable mass concentration (3700 μg m-3) was monitored during packing of ce