"The vehicle cabin can be viewed as a buffer, protecting us from the outside air," said Leavey. "While driving with your air conditioning on and windows closed is the most protective thing that you can do, running the AC can decrease your fuel economy. That's why adopting a dynamic behavior modification approach is recommended, in which the AC or closed windows are used when following a highly polluting vehicle, or on the freeway which tends to be more highly polluted. Once you have left the polluted environment, we recommend opening your windows to remove any pollutant build-up from your car. " Explore further: Time spent in car drives up air pollution exposure
However, according to several authors, most of these gains have been lost, especially due to stubble burning , rise in market share of diesel cars and a considerable decline in bus ridership.   According to CUE and System of Air Quality Weather Forecasting and Research (SAFER), burning of agricultural waste in nearby Punjab, Haryana and Uttar Pradesh regions results in severe intensification of smog over Delhi.   The state government of adjoining Uttar Pradesh is considering imposing a ban on crop burning to reduce pollution in Delhi NRC and an environmental panel has appealed to India's Supreme Court to impose a 30% cess on diesel cars.