Respiratory system evaluation and screening can easily be done by Pulmonary Function Tests. It is an important and useful adjunct for correlation and evaluation of, the presenting complaint of patients like cough and dyspnoea, the imaging studies and pre and post treatment respiratory function status, as well as to identify patients with no or insignificant signs and symptoms of respiratory impairment.

Keeping in mind, the huge physiological and clinical importance I decided to carry out this study. In present study the pulmonary function test of smokers were compare with non-smokers. So, it is expected that this knowledge smoking among the people of Northern Bihar (Koshi region) Bihar, where a large population is migrant workers, with poor hygiene and low socioeconomic status, this study was undertaken for a better understanding of the correlation between smoking and its effects on pulmonary functions.