The government today said that it is monitoring the trend of various air pollutants across the country under the National Air Quality Programme. Environment Minister Anil Madhav Dave said in New Delhi that the monitoring network comprises 680 manual stations spread over 300 cities in 29 states. <br/><br/>The Minister informed that government has embarked upon universalization of BS-IV standards by 2017 for all types of vehicles. Mr Dave said it has also been decided to leapfrog from BS-IV to BS-VI standards within the next three years by April 2020. He said, government has banned burning of leaves, biomass and municipal solid waste to control pollution in the NCR. Mr Dave said values of SO2 are within permissible limits in Delhi while NO2 is fluctuating and slightly above the permissible limits.