Exposure to nanoparticles in thermal spraying - Vigilance towards the operator and the outside environment

The previous survey of the French CaRPE project has shown a lack of information and showed the interest to assess the residual exposure to these particles. This paper presents the results of various sampling operations and emission analyses of plasma spraying equipment. For this purpose, different areas have been targeted, such as at the level of the emissions channeled upstream and downstream of the filtration system, at the workstation level as well as fugitive emissions. Various measurements were carried out: real-time particle size distribution, mass concentration of total suspended dust, heavy metals, sampling characterization by EDX/ MET, etc. The metallic aerosol is mainly composed of nanometric structures. The number concentration is particularly high (between 108 and 109 particles/cm3) downstream the filtration system. Measurements upstream and downstream of the filtration system have made it possible to determine its efficiency, which is greater than 90%. The mass concentration downstream of the filter is ~2.6 mg/m3 while the number concentration remains above 106 particles/cm3. Some recommendations were then derived. Very great vigilance is therefore recommended in order to protect the operator, since we must remember that we are in the presence of a very high concentration of metallic and nanostructured particles.