Why Winter Brings Deadly Smog to India’s Capital

(Bloomberg) -- Millions of Indians are breathing in the world's most toxic air. Each winter, thick smog envelops the capital of New Delhi and numerous cities across the dusty and densely populated North Indian plains. Chief Minister Arvind Kejriwal, the leader of the metropolis that's home to 20 million people, called New Delhi a “gas chamber.” An estimated 1.1 million people died as a result of air pollution in India in 2015, according to the non-profit Health Effects Institute. The air has since gotten worse.

1. What causes the pollution?

Vehicle and industrial emissions contribute year-round, as do road and construction dust and domestic fires lit by the poor. But a grim extra wallop comes late in the year from the burning of crop stubble, which continues despite being banned in the surrounding states of Punjab, Uttar Pradesh, Haryana and Rajasthan. Farmers traditionally clear fields by burning in preparation for the winter season. Compounding the problem: The trough-like topography of north India means polluted air lingers in colder months.

2. What is the point of stubble burning?

After rice, wheat or other grain is harvested, the straw that remains is called stubble, and it must be removed before the next planting. It once was used as cattle feed, or to make cardboard, but harvesting by combine (rather than by hand) leaves 80 percent of the residue in the field as loose straw that ends up being burnt. Disposal by means other than burning -- such as plowing it into a fine layer of field cover -- costs time and money, two things that farmers say they can't afford.

3. How serious is the health risk?

The Lancet estimates that 6.5 million people die annually around the world because of air pollution, mostly in India and China. The most dire threat to humans is from PM 2.5, the fine, inhalable particles that lodge deep in the lungs, where they can enter the bloodstream. World Health Organization guidelines say exposure to PM 2.5 above 300 micrograms per cubic meter is hazardous. New Delhi's readings have exceeded 1,000.

4. Where else in India is pollution a serious problem?

India accounted for the world's 10 most-polluted cities, as measured by PM 2.5, in WHO's 2016 rankings. The industrial city Kanpur was worst, with New Delhi sixth. Also in the top 20 were Indian tourism favorites Jaipur, Jodhpur and Agra (home to the Taj Mahal), as well as Peshawar and Rawalpindi over the border in Pakistan. For the less fine PM10 particles, New Delhi ranked as the world's most polluted city. It got so bad in 2017 that schools were closed (children are among the most severely effected), flights were canceled and an international cricket match was halted as smog caused players to vomit.

5. Why not strictly enforce the ban on burning?

Farmers are a strong electoral constituency, and many argue that it is cheaper to burn the crops than rent equipment. India's environment ministry says the ban is proving more effective this year and that the number of fires had fallen ahead of peak burning season in late October and early November.

6. Does the problem end when the burning stops?

The worst of the pollution typically dissipates as spring begins, but New Delhi's air remains dirty all year. On every day in 2017, PM 2.5 readings exceeded the level deemed healthy by the WHO (up to 50 micrograms per cubic meter). And there were 39 days when readings topped 300, according to U.S. embassy data through Nov. 20.

7. What action is India taking?

Unlike in China, where the one-party state has directed a concerted nationwide anti-pollution drive, India's various levels of government have struggled to make similar progress. The Supreme Court in 2016 mandated government action such as banning construction as pollution levels reach thresholds. The federal government says it's now following a national clean air strategy, but activists criticize it for lacking hard targets and clear compliance mechanisms. On the positive side, New Delhi closed down its Badarpur coal-fired power plant in October has taken small steps such as cracking down on polluting vehicles.

8. What's the impact on the economy?

By the World Bank's calculations, health-care fees and productivity losses from pollution cost India as much as 8.5 percent of GDP. At its current size of $2.6 trillion that works out to about $221 billion every year.

9. What more can India do?
Critics say it should more quickly coordinate antipollution efforts across all levels of government and boost resources to enforce rules such as the crop burning ban and limits on dust at construction sites. Continuing to adopt cleaner fuels such as compressed natural gas and introducing policies to rapidly boost electric car usage would also help, as would strengthening the public transport system to reduce the number of vehicles on the road.

The Reference Shelf

The world's fastest-growing economy has the world's most toxic air.
For farmers like Prithvi Singh, it all boils down to expense.
A QuickTake explainer on China's smog.
This is Pakistan's problem, too.
Bad air means good business for some.
The WHO's air pollution database.
Towards a Clean-Air Action Plan. A report by India's Centre for Science and Environment.

--With assistance from Pratik Parija and Jeanette Rodrigues.

To contact the reporters on this story: Iain Marlow in New Delhi at imarlow1@bloomberg.net;Anindya Upadhyay in New Delhi at aupadhyay22@bloomberg.net

To contact the editors responsible for this story: Arijit Ghosh at aghosh@bloomberg.net, ;Ruth Pollard at rpollard2@bloomberg.net, Grant Clark