Firefighting is regarded as possibly carcinogenic, although there are few mechanistic studies on genotoxicity in humans. We investigated exposure to polycyclic aromatic hydrocarbons (PAH), lung function, systemic inflammation and genotoxicity in peripheral blood mononuclear cells (PBMC) of 22 professional firefighters before and after a 24-h work shift. Exposure was assessed by measurements of particulate matter (PM), PAH levels on skin, urinary 1-hydroxypyrene (1-OHP) and self-reported participation in fire extinguishing activities. PM measurements indicated that use of personal protective equipment (PPE) effectively prevented inhalation exposure, but exposure to PM occurred when the environment was perceived as safe and the self-contained breathing apparatuses were removed. The level of PAH on skin and urinary 1-OHP concentration were similar before and after the work shift, irrespective of self-reported participation in fire extinction activities. Post-shift, the subjects had reduced levels of oxidatively damaged DNA in PBMC, and increased plasma concentration of vascular cell adhesion molecule 1 (VCAM-1). The subjects reporting participation in fire extinction activities during the work shift had a slightly decreased lung function, increased plasma concentration of VCAM-1, and reduced levels of oxidatively damaged DNA in PBMC. Our results suggest that the firefighters were not exposed to PM while using PPE, but exposure occurred when PPE was not used. The work shift was not associated with increased levels of genotoxicity. Increased levels of VCAM-1 in plasma were observed. Environ. Mol. Mutagen. 59:539-548, 2018. © 2018 Wiley Periodicals, Inc.