High Magnetic Property and Toxicity of Particulate Matter Generated during Welding and Cutting Processes

Magnetic particulate matter (PM) has raised increasing concern due to its abundant presence in ambient air and negative health impact. However, there is still a lack of comprehensive understanding of their emission sources and toxicities. We here report the observation of high magnetic property and toxicity of PM generated during typical welding and cutting processes. Magnetite, formed during high-temperature operation with less oxygen pressure, was revealed to be the major magnetic contributor. The averaged saturation magnetization and magnetic susceptibility values of fine PM (PM_2.5) from welding processes are 1.4-4.2 times greater than those of PM emitted from other unintended emission sources, including iron and steel plants and brake wear, while they are 2.0-5.7 times greater for the cutting processes. Furthermore, PM_2.5 from welding and cutting processes are nearly 3.5-4.5 times more neurovirulent and 2.1-7.0 times more likely to induce oxidative stress than those from other magnetic sources in the nerve cells lines. Moreover, all of these magnetic PM_2.5 exhibit greater negative health effects than typical atmospheric PM_2.5 collected in Shanghai urban regions. These new findings suggest that appropriate occupational protection measures should be implemented for the welding and cutting process to reduce adverse health impacts.