Pulmonary responses of children chronically exposed to ambient air pollution in Calcutta have been investigated. A total number of 153 children from Calcutta and 116 from rural West Bengal in the age group of 6-17 yr were included in this study. Respiratory symptom complex, sputum cytology and micronucleus (MN) count of buccal epithelial cells were evaluated. Blood smears were examined for WBC differential count and RBC morphology.