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A hazy view of metro train running as the area covered with the thick layer of smog due to air pollution, in New Delhi on Thursday. (ANI Photo)
A hazy view of metro train running as the area covered with the thick layer of smog due to air pollution, in New Delhi on Thursday. (ANI Photo)

The great Indian pollution menace, in six charts

  • Long term exposure to PM2.5 has already cost millions of lives in India due to heart and lung diseases. It may now be driving up covid-related deaths

Blue skies during the lockdown months made us hopeful about a different winter this time. That hope has been belied.Air pollution in most Indian cities was far worse in October than what it was in 2019, Mint reported last month.

November has been no different so far.

As air quality declined over the past few weeks, respiratory problems shot up across cities, the healthcare app Practo reported.

Delhi, among the worst affected cities, saw a surge in covid-19 cases over the same period. Now, the death toll is also rising rapidly. The national capital accounted for 21% of all covid-related deaths in the country over the past week, according to Mint’s latest covid tracker update.

Even short term exposure to severe air pollution can cause serious damage, especially during the outbreak of a respiratory infection such as covid. Research shows that cases of flu hospitalisation and deaths rise in the months of higher pollution.

There is some research now to suggest that covid-19 outbreaks have worsened in more polluted regions.

Our political class has been oblivious to the build-up of this crisis. Even in a pandemic year, the same old script played out. As the air quality began to dip, Delhi’s chief minister laid the blame on farmers who were burning stubble in the neighbouring states of Punjab and Haryana. The Union environment minister dismissed this by arguing that crop burning contributes only 4% towards Delhi-NCR pollution.

That led to a war of words between the two, even as citizens suffered in Delhi and neighbouring states where new infections have spiked, such as Haryana.

If we consider the entire winter season (Nov-Feb), as was done in the ARAI-TERI 2018 study on source apportionment, crop burning indeed accounts for roughly 4% of Delhi’s air pollution. But this average figure, which the environment minister possibly relied on, hides significant daily differences, and also misses out on the impact of crop burning in October, when stubble burning is quite high. During the peak stubble burning phase, crop burning accounts for more than 50% of Delhi’s air pollution, according to data from System of Air Quality and Weather Forecasting And Research (SAFAR).

Crop burning usually peaks during the late October-early November period and contributed around 24% of air pollution in the capital in November 2019, said Sumit Sharma, director at The Energy and Resources Institute (TERI) in Delhi. But the contributions are episodically high and hence the average contribution across the entire winter season is low, he added. Other researchers have also arrived at similar conclusions about crop burning playing a major role in air pollution in the Oct-Nov phase.

Unfavourable meteorological conditions in late October and early November also worsened the capital’s air pollution problem this time. Reduced wind speed and lower temperatures inhibit dispersion of particulate matter emitted by various sources, worsening the concentration of tiny polluting particles such as PM2.5. This year, Delhi saw its coldest October in the last 58 years.

Low wind speed added to the problem.

“In the first week of November, Delhi experienced severe air quality on account of the northwesterly winds which led smoke from Punjab to flow towards Delhi," said Kurinji Selvaraj, an analyst at the Delhi-based think-tank, Council on Energy, Environment and Water (CEEW). During 10-12 November, higher wind speeds with a shift in wind direction led to an improvement in air quality even as the share of stubble burning among pollutants fell, she added.

Bad air in India is not a winter-only or Delhi-only problem, even if the problem reaches its peak in the winters and Delhi gets hit harder than other cities. Most parts of the country, and particularly the Gangetic belt, breathe in bad air for much of the year. In winters, this takes the form of a public health emergency. The two problems are interlinked even though the sources of pollution and the meteorological factors that impact the concentration of pollutants in the air tend to be different in different seasons.

14 Indian cities featured among the 20 most polluted cities of the world in 2019, according to the air quality portal IQAir.

The contribution of different pollutants varied, according to an assessment program of 50 cities undertaken by the environmental portal urbanemissions.info the same year. On average, transport emissions (18%) and dust (15%) are the dominant pollutants across cities, the assessment found. But a large share of pollutants flows in from outside.

The data suggest that it is important to consider the regional rather than just the local sources of pollution while addressing the problem. Pollution is what economists regard as a negative externality: polluting activity in one region imposes harm in another.

The level of harm that pollution causes has been exceptional in India. In 2019 alone, exposure to PM2.5 caused about a million deaths in India, according to the State of Global Air 2020 report, published by the Health Effects Institute and the Institute for Health Metrics and Evaluation's Global Burden of Disease (GBD) project.

Exposure to PM2.5 took 4.1 million lives globally last year. India and China accounted for 58% of these deaths.

Because of long-term exposure to pollution, diseases such as diabetes, respiratory infections, and chronic lung diseases kill many more people in India than in the rest of the world, the GBD study showed. These are also diseases that increase vulnerability to covid-19, research has shown.

The surge in covid-19 cases in Delhi and Haryana over the past few weeks has lent an urgency to the air pollution debate in the national capital. But even without a pandemic, pollution is a major killer in India, the data show.

This is the first of a two-part series on India’s pollution problem.

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