Occupational exposure to welding gases during three welding processes and risk assessment by SQRCA method

Hazardous chemical agents in the welding operation are a mixture of metal fumes and toxic gases, the inhalation of which causes adverse health effects among welders. The emission of gases in the workplace is a logical cause for concern regarding the potential development of respiratory disease. The aim of the present study was to determine the concentration values of gases discharged during arc welding and perform risk assessment through semi-quantitative chemical risk assessment ý(SQCRA) method.
This cross-sectional study was conducted in an Iranian steel mill on the 3 processes of plasma arc welding (PAW), submerged arc welding (SAW), and gas tungsten arc welding (GTAW). Direct reading instruments were used for sampling of carbon dioxide (CO2), carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2), and ozone (O3). SQCRA method was used for risk assessment of gases.
The concentrations of O3 (0.356 ppm), CO (41.642 ppm), NO (6.357 ppm), and NO2 (4.871 ppm) were found to exceed their threshold limit values (TLVs), while the concentrations of CO2 (3879.285 ppm) were below its TLV. The maximum exposure concentration of all gases, except CO2, was observed in SAW. SQCRA method showed that among the gases, the highest and least risk rating was related to ozone and nitrogen monoxide, respectively. The risk rating for CO2, CO, and NO2 was low, high, and very high, respectively.
In this study, exposure values were higher than the threshold limit values-time weighted average (TLV-TWA) and the results of risk assessment showed that control engineering should be applied and the use of respiratory protective equipment (RPE) should be made mandatory for welders especially in SAW, PAW, and GTAW processes.