Delhi Can’t Breathe: Why Do Indian City’s Have the Most Polluted Air on the World?

Every winter, the air of Delhi becomes an unbreathable morass. By some estimates, breathing one day of Delhi air when air quality is at it’s worst is equivalent to smoking 44 cigarettes and the toxic air reduces life expectancy by approximately six years. The burden of air pollution falls especially hard on the elderly and infirm, and an entire generation is growing up breathing suffocating levels of pollution. According to the World Health Organization, Delhi is the most highly polluted megacity in the world, and three of the ten most polluted cities in the world are in the neighborhood of Delhi. In today’s podcast episode, I discuss the agricultural origins of air pollution in Delhi, I discuss the non-agricultural sources of pollution, and the environmental Kuznets curve.

In a previous podcast episode, I discussed the environmental ramifications of the green revolution.  One that I did not discuss was the air pollution created by the burning of rice stubble after the harvest. Modern mechanized harvesters leave a large amount of rice straw that needs to cleared before the planting of the winter wheat crop. The cheapest and fastest method to clear the fields is to burn to rice straw,  and more than 2 million farmers burn 23 million tons of rice residue over 80,000 sq km of farmland resulting in massive fires. As much as a third of the air pollution comes from these fires. Although the government has banned burning rice residue, the state governments have struggled to do so. For one thing, government policies such as enforced sowing times and large subsidies of mechanized harvesters only encourages more burning. The government has provided subsidies of 80% for the purchase of mulchers that process rice, but it is a slower process that costs 3 times more than burning the fields after subsidies are taken into account.

Many of the sources of air pollution come much closer to the city of Delhi. India is a major importer of Petroleum Coke, a by-product of refining heavy oils such as those produced in Canadian tar sands and emits twice as much sulfur as coal making it one of the most polluting sources of energy. The Indian government has announced a partial ban on the import of petcoke for 2018, although certain industries are exempt. Similarly, the rapid growth of diesel car use has had a strongly negative impact on air quality. The number of cars in Delhi has more than tripled over the last 8 years.  Moreover, between 2004 and 2014 the percent of cars sold in India that used diesel went up from one quarter of all cars to one half.  In 2014, the government of India phased diesel subsidies out, and demand for diesel cars has collapsed. Only 23% of all cars sold in 2018 are expected to be diesel. Finally, coal, the only natural resource India has ample reserves of, is a major contributor to air pollution. There are over a dozen thermal coal power plants surrounding Delhi and the largest Badarpur, had long been falsifying records on emissions to pass standards. The Badarpur powerplant, and many others are being phased out to help reduce levels of air pollution.

One of the most important ideas for understanding air pollution in Delhi is the environmental Kuznets curve. The idea of the Kuznets curve is that levels of air pollution are lowest in low and high income countries, but much higher in middle income countries. India’s rapid economic growth means it is rapidly approaching middle economic status has resulted in a massive increase in pollution. Many cities in the developed word such as Pittsburgh and Manchester were once famous for being the types of places where a person could go to work in a white shirt and come back in a gray one. It is a process we have seen in Beijing, which for a long time was considered the most polluted city in the world. However since 2013, Beijing and the Chinese national government has placed draconian measures to curb pollution. Coal use was cut by one half since 2013, and major construction and steel projects mothballed. Levels of air pollution are down by 20% since 2013. The experience of Beijing shows that the Kuznets curve isn’t a natural inevitability, but the result of sustained changes in policy.


Economic growth and environmental degradation: the environmental Kuznets curve and sustainable development ;   David Stern, Michael Common, Edward Barbier

Off Target: Status of Thermal Power Plants in Delhi NCR ; Centre for Science and Environment