Occupational exposure to nanoparticles originating from welding – case studies from the Czech Republic

Abstract

Background: Nanomaterials are virtually ubiquitous as they are created by both natural processes and human activities. The amount of occupational exposure to unintentionally released nanoparticles can, therefore, be substantial. The aim of the study was to determine the concentrations of incidental nanoparticles that workers can be exposed to during welding operations and to assess related health risks. The specific focus on welding operations was determined based on the fact that other case studies on the manufacturing industry confirm significant exposure to incidental nanoparticles during welding. In the Czech Republic, 92% of all industrial workers are employed in the manufacturing industry, where welding operations are amply represented. Material and Methods: The particle number concentrations of particles in the size range of 20-1000 nm and particle mass concentrations of inhalable and PM1 fractions were determined via measurements carried out at 15-minute intervals for each welding operation by static sampling in close proximity to the worker. Measurements were obtained using the following instruments: NanoScan SMPS 3910, Optical Particle Sizer OPS 3330, P-TRAK 8525 and DustTrak DRX 8534. The assessed operations were manual arc welding and automatic welding. Results: The observed average particle number concentrations for electric arc welders ranged 84x10(3)-176x10(3) #/cm(3), for welding machine operators 96x10(3)-147x10(3) #/cm(3), and for a welding locksmith the obtained average concentration was 179x10(3) #/cm(3). The determined average mass concentration of PM1 particles ranged 0.45-1.4 mg/m(3). Conclusions: Based on the conducted measurements, it was confirmed that there is a significant number of incidental nanoparticles released during welding operations in the manufacturing industry as a part of production and processing of metal products. The recommended occupational exposure limits for nanoparticle number concentrations were exceeded approximately 4-8 times for all assessed welding operations. The use of local exhaust ventilation in conjunction with personal protective equipment, including FFP2 or FFP3 particle filters, for welding is, therefore, recommended.