To clean oily or greasy parts in mechanical maintenance shops, workers use biowashers or biological degreasing stations. The degreasing agents in these washing stations contain bacteria for which no metrological data were available for assessing the occupational risk of exposure through inhalation. To address this lack of data, the researchers monitored five biological degreasing stations for a year, taking 50 mL samples of degreasing fluid every two months and, for comparison purposes, an initial sample of unused degreaser from each station. Using a variety of methods, the researchers counted and identified the bacteria that colonized the degreasers. They detected 60 species of bacteria at concentrations ranging from 3.6 x 104 to 2.6 x 107 CFU/mL in the used fluids, whereas only one species, Bacillus subtilis, was found in the unused fluids.