A recent World Bank report shows that the economic cost of damage to public health from increased air pollution is still very high in Indian cities. The study, India Strengthening Institutions for Sustainable Growth, says that the cost in 50 cities with a population of 110 million reached a whopping Rs 15,000 crore (US $3 billion) in 2004. This increase has been attributed to the high levels of particulates with diameter less than 10 micron (PM10) in the cities.

An earlier World Bank estimate published in 1995 for 36 Indian cities had said that the total health costs resulting from high air pollution (exceeding the guidelines set by World Health Organization) varied from US $0.5 billion to US $2.1 billion.

The latest findings reveal that the PM10 levels for large cities like Delhi, Mumbai, Kolkata, Ahmedabad and Hyderabad have decreased. On the other hand, there has been a steady increase in PM10 levels in smaller cities like Bhopal, Nagpur, Jaipur, Kanpur, Jalandhar, Indore, Faridabad, Surat and Vishakhapatnam.

Currently, the average PM10 exposure level in smaller cities is slightly higher than that for the larger ones, says the study. "This is a result of greater attention and effort given to arresting air pollution in larger cities,' it adds. The Central Pollution Control Board's PM10 data for 2004 reveals that Kanpur is more polluted than metros like Delhi, Mumbai and Chennai among others.