We investigated the microbial flora of the MWF and the air, the oil mists, the inhalable dusts, and the endotoxins on 44 machining sites in 25 Québec plants. [...] Quantitative PCR was used to count the total bacteria as well as the mycobacteria of the species Mycobacterium immunogenum, while the PCR DGGE technique was used to describe the microbial biodiversity present in the different samples. [...] Identification by affiliation with the closest microorganism is noted, as well as the number of base pairs used for identification and the percentage of similarity Table 6: Affiliation of the different ribotypes found in the DGGE profiles carried out with the cutting fluid samples Table 7: Characterization of the aerosols on the different machining sites Table 8: Frequency and affiliation of the i [...] In Québec, the only published studies interested in the microbial contamination of MWF were carried out by our team (IRSST exploratory study and Mycobacterium immunogenum-Fondation JD Bégin) and no study has investigated the state of respiratory health of workers exposed to the bioaerosols generated in the use of cutting fluids. [...] In fact, they participated in the development of the questionnaires evaluating the workers’ dermatological health, in the training of the nurse who had to meet with the workers, and in the analysis of the results.