The hardening of metals involves the immersion of hot components in mineral oil with production of aerosols containing PAHs, to wich workers can be exposed. The determination of airborne PAHs and urinary 1-hydroxypyrene (1-OHPy) was performed for a group of workers and the latter resulted within the reference values. However, the average 1-OHPy concentration on metal workers (0.07 microg/g creatinine) was statistically different from the average value obtained for a group of employees (0.03 microg/g creatinine), highlighting the risk of exposure to PAHs. Therefore, being these potentially carcinogenic compounds, interventions were prescribed in order to reduce the risk of occupational exposure.