Background: The present study investigates the effect of different concentrations of air pollutants (PM10, O3. H2S) on the function of lung.

Materials & Methods: Arak and Khomain cities were divided into 10 and 5 regions, respectively. A sample of air pollutants (PM10, O3 .H2S) was measured by PSI (pollution standard index) machine randomly from spring to winter. Two random samples consisting of 1069 non-smoker residents of the two cities (522 from Khomain and 547 from Arak) were selected. Regression test mode were used to analyze data.

Results: PSI in the cities Arak and Khomain was 101.83±14.54 and 89.17±18.58, respectively. Predicted values of FVC, FEVI, FEF 25-75%, MEF 50%, and PEF in Arak were 10.2%, 11.7%, 35.5%, 30.9%, and 40% abnormal, respectively. These values in Khomain were 8.8%, 11.3%, 35.4%, 33.9%, and 40.6% abnormal, respectively. The concentrations of H2S in both cities were above the standard values. There was no significant relationship between the concentrations of O3, H2S, PM10 and vital capacity. However, there was a considerable correlation between the mean of FEF, FEF 25–75%, and concentration of O3 at P<0.001 and P=0.016 level of significance, respectively. In Arak the correlation observed between FVC and concentration of O3 was not significant. In Khomain a negative correlation was observed between VC with H2S and PM10 on one hand and FVC with H2S and PM10 on the other.

Conclusion: The main pollutants in Arak was PM10 and in Khomain were H2S and O3. Measuring these pollutants throughout the year is necessary.