Background: There is consistent evidence that cleaning workers are at high risk of developing asthma. Predisposing factors are not fully understood and it is important to produce evidence that this risk is work-related. Objective: To assess whether the work environment induces pulmonary inflammation in asymptomatic cleaning workers and to determine the efficacy of noninvasive methods to detect early pulmonary inflammation. Methods: Sixty-seven workers were evaluated by comparing sputum cytology, fractional exhaled nitric oxide (FeNO) values and spirometry tests, performed during the work period and after vacations. Results: We observed a significant increase in FEV1 values after the vacation period (pre 2.90L ± 0.57L and post 2.94L ± 0.61L, p <0.05), even though those values were within normal limits, in both periods. There was a reduction in the values of the FeNO measurements after vacations (pre 16.3 ± 9.7 and post 13.8 ± 7.8, p <0.05) and a reduction of inflammatory cells count in the induced sputum (Eosinophils: pre 0.019 ± 0.05 and post 0.003 ± 0.01, p <0.05 Lymphocytes: pre 0.16 ± 0.35 and post 0.01 ± 0.09, p <0.05 Macrophages: pre 0.421 ± 0, 47 and post 0.235 ± 0.30, p <0.05. Conclusion: We observed that the occupational environment to which the studied population was exposed caused inflammation in the airways without functional abnormalities. Noninvasive methods such as counting of cells after induced sputum and FeNO measures showed to be promising tools for the detection of pulmonary inflammation, although they still require standardization.