The objective of this study was to determine the prevalence of lung abnormality when comparing street sweepers who work in inner and outer region of Bangkok Metropolis. The study assesses the factors related to the pulmonary function deterioration, and determines the relationships between the various factors with pulmonary function deterioration, of the street sweepers. The sample was selected through a random sampling technique called two-step sampling proportional to size. The population of the Rattanakosin group had a total of 1725 street sweepers with the sample group equal to 268 people, and the population of the Srinakarin group had a total of 1300 street sweepers with the sample group equal to 202 people. This research used an interview questionnaire for personal data collection, air sampler for respirable dust measurement, and spirometry for pulmonary function testing. The results of the pulmonary function test of both groups revealed that the mean FVC, FEV1, and FEF 25-75% of the street sweepers in the Rattanakosin group are significantly lower than the mean predicted values (p-value < 0.001).The mean FVC, FEV1, and FEV1/FVC of the street sweepers in the Srinakarin group are significantly lower than the mean predicted values (p-value = 0.001), and the mean FVC and FEF25-75% of the street sweepers in the Rattanakosin group are significantly lower than the mean values of the street sweepers in the Srinakarin group. (p-value = 0.001 and p-value = 0.005 respectively). The prevalence of lung abnormality in the Rattanakosin and Srinakarin groups are 29.74% and 15.95% respectively. It was found that the number of years of employment affects the abnormalities in FVC, FEV1 and FEF 25-75%, (p-value < 0.001, p-value = 0.013, and p-value < 0.001) and smoking affects the abnormality in FEF25-75%. (p-value = 0.004)