Risk assessment of welding operations and processes in terms of ultrafine particles emissions

• Main Author: Gomes, João
• Publication Date: 2021
• Other Authors: Miranda, Rosa M., Esteves, Helder M., Albuquerque, Paula
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10400.21/16072
• topic: Occupational health; Occupational exposure; Ultrafine particles; Welding operations; Risk assessment

Welding is extensively used in metallic construction worldwide, in spite of being able to produce dangerous fumes that may be hazardous to the welder’s health. It is estimated that, presently, 1-2% of workers from different professional backgrounds (which accounts for more than 3 million persons) are subject to welding fume and gas action. Recently, studies have proved the existence of ultrafine particle emissions, from welding processes, thus increasing the health risks to exposed welders. In particular, it was found that the amount of emitted particles (measured by particle number and alveolar deposited surface area) is clearly dependent on the distance to the welding front, and also on the main welding parameters, namely the applied current intensity, heat input, nature of base metal, nature of addition metal, and nature of welding gases used. The emission of airborne ultrafine particles increases with the increase of current intensity as the fume-formation rate does. In regards to welding gas mixtures, higher emissions are observed for more oxidant mixtures, that is, mixtures with a higher CO2 content, which result in higher electric arc stability. These mixtures originate higher concentrations of ultrafine particles (as measured by the number of particles per cm3 of air) and higher values of the alveolar deposited surface area of particles, thus resulting in more severe worker exposure. Combining the obtained data, it is possible to compare different welding processes and operating conditions, in order to assess different levels of welder’s exposure. Also, the graphical representation of measured concentrations of airborne ultrafine particles, with time and distance, allows us to define “safe” and “critical” regions within a welding workshop in terms of welder exposure. This information may be combined with the results of risk analysis derived by control banding and helps to categorize the sites where regulatory measures such as operation containment or dedicated exhaust ventilation need to be implemented.