The project aims to investigate the impacts of high particulate matter on human respiratory health in selected mega-cities of South Asia where the particulate matter loading, in general, in ambient air is very high due to various anthropogenic activities. The urban air pollution impacts on human health have assumed significant importance in South Asian region; however available studies are limited. It is proposed to carry out this study using questionnaire based sample surveys. The surverys will be specially designed to analyse and segregate various confounding parameters in the target population and localities in mega-cities of South Asia ( Colombo, Delhi, Dhaka, Karachi, Kathmandu, and Kolkata). This proposal brings together the physical and medical scientists of the region to pool their expertise for the benefit of South Asia.