Objective: To determine the effects of fuel vapor exposure on pulmonary function among informal sellers. Methods: Cross-sectional study carried-out among informal fuel sellers in Maicao, Colombia. Sociodemographic data were gathered as well as pulmonary function by spirometry, pulse oximetry and evaluation of biomass exposure. Results: 74 patients were evaluated; 87.8% were males, 71.6% of them had between 18 to 40 years of age; 21.6% (n=16) reported pulmonary diseases; 59.4% had a predicted FEV1 <80%; 68.9% had a predicted FVC <80% and 32.4% had a predicted FEV1/FVC < 70%. Among those who had abnormal spirometry, (n=45) 62.2% reported to had worked ≥5 years. The most common reported symptoms were dysphonia (14.8%), conjunctivitis (14.8), epigastric pain (10.8) and headache (9.45%). No statistically significant differences were found between spirometry alterations and history ...