Bus ridership in Delhi has dropped from 60% in 2000 to 41% now. Every year, Delhi needs an area the size of 310 football fields for parking its vehicles. And Delhi has one of the highest particulate matter (PM10) levels in South Asia. These are some of the findings of a recent Centre for Science and Environment (CSE) assessment of air pollution and policies of different cities in dealing with it. That gives you a comprehensive picture of the growing vehicular population and the resultant pollution.