['Little data exist on short- and long-term effects of occupational exposure on airway and systemic inflammation in professional firefighters. We aimed to characterize airway and systemic inflammation in training firefighters with a maximum occupational exposure of 1 year compared to the long-term exposure of professional firefighters.', 'A questionnaire for symptoms and exposure, pulmonary function, atopy, bronchial hyper-responsiveness, and markers of inflammation in induced sputum, serum, bronchoalveolar lavage (BAL) fluid and bronchial biopsies were assessed in a total of 92 firefighters (63 full-time professionals and 29 trainees).', 'Professional firefighters showed allergic bronchial sensitization documented by the presence of atopy, and eosinophilia in induced sputum, BAL and bronchial biopsies. IL-8, ECP, VEGF, and TNF-α levels were statistically significantly higher in the sputum supernatants of professional firefighters compared to the trainees (p\xa0=\xa00.04, p\xa0=\xa00.02, p\xa0=\xa00.04, and p\xa0=\xa00.02, respectively). Serum IL-8 and TNF-α levels were also statistically significantly higher in the group of professional firefighters (p\xa0=\xa00.04, p\xa0=\xa00.03, respectively). Finally, there was a linear correlation between the duration of the occupation in Service and the degree of airway and systemic inflammation.'] Does prolonged occupational exposure lead to allergic airway sensitization and chronic airway and systemic inflammation in professional firefighters?