Assessment of workers' exposure to microorganisms when using biological degreasing stations

Biological degreasing stations (BDSs) are used by mechanics. These BDSs use a water-based solution with a microbial degradation process. Occupational exposure during the use of BDSs has not been reported and few studies have identified the bacteria present. The objectives were to measure the concentration of microorganisms during BDSs' use and monitor the bacterial community in the liquid over time. Five mechanical workshops were studied. Six 30-min samples were taken at each workshop over one year. Bioaerosols in the ambient air samples were collected with Andersen impactors near the BDS Bioaerosols in the workers' breathing zone (WBZ) were collected on filters. Fresh bio-degreasing fluids were collected from unopened containers, and used bio-degreasing fluids were collected in the BDS. The results show that the use of BDSs does not seem to increase bioaerosols concentrations in the WBZ (concentrations lower than 480 CFU/m³) and that the bacterial communities (mainly yeasts, Bacillus subtilis and Pseudomonas aeruginosa) in the bio-degreasing fluids change through time and differ from the original community (B. subtilis). This study established that workers using BDSs were exposed to low levels of bioaerosols. No respiratory protection is recommended based on bioaerosols concentrations, but gloves and strict personal hygiene practices are essential.