Most of the world’s polluted cities are in the Indian subcontinent. Greenhouse gas from the road transportation sector mainly comes from the exhaust of cars, motorbikes, and commercial vehicles. Most of the fuel used in road transportation is petrol or diesel, while recently, some are powered by natural gas. From private cars to public transport vehicles, the city of Delhi has encouraged the switch from petrol and diesel to compressed natural gas (CNG) to decrease emission levels.
India has the second largest road network globally, with close to five million kilometers of roads across the country in 2016. The Indian road network consists of expressways, national and state highways, and other major districts and rural roads. Unsurprisingly, the heavily polluted capital city of Delhi had the most extensive road network among the metropolitan cities. In a bid to reduce pollution levels, anti-pollution measures such as odd-even scheme – allowing number based on their registration numbers on the road, increasing public transportation and carpooling has been encouraged in the capital city.