The City of Delhi, with a human population of over 16 million has nearly 9 million vehicles on its roads running over 100 billion kilometers every year, spewing out nearly 4 million tonnes of fuel emissions into the atmosphere every year (9900 tonnes per day). About 2 to 5% of these emissions (about 200 to 500 tonnes per day) are in the form of highly toxic gases and particulate matter hazardous to human health and well being.