Some 60000 trucks trundle through Delhi every day. They are poorly maintained, run on high sulphur diesel and are the cause of air pollution. 'The trucks use diesel with 2500 ppm (particles per million) sulphur. This means the sulphur content is five times more than the 500 ppm diesel we use of here' says Sunita Narain, director of Centre for Science and Environment (CSE). Delhi sells Euro-II complaint low sulphur diesel, which is available only in four metros.