Abstract
Plasma spraying is widely used in industries such as aerospace and energy, yet quantitative data regarding its emissions of Nano Objects, Aggregates, and Agglomerates (NOAA) remains limited. This study assesses onsite particle emissions at an industrial facility, evaluating channeled emissions, filtering efficiency, diffuse emissions, and worker exposure. The results show that while mass-based filtering efficiency exceeds 90%, approximately 106 submicrometric particles cm-3 still bypass the filters. Significant diffuse emissions (>105 particles cm-3 above background) were detected when opening the spray booth doors. Furthermore, exposure measurements indicate a high risk for workers who enter the booth without sufficient abatement time, with particle counters reaching saturation at 106 particles cm-3. Notably, the dustiness of the process-generated powder was found to be 200 times higher than that of the raw material. Despite the current lack of specific NOAA regulations, these findings provide critical insights into the environmental and occupational health impacts of plasma spraying, serving as a baseline for future safety protocols and regulatory frameworks.