Satellite images help explain why Delhi’s air remains toxic and Beijing’s is getting better

NASA Worldview/The Washington Post

Only a few years ago, the capitals of Asia’s two biggest nations — India and China — were hovering around the same toxic air pollution levels. Today, the two cities are hardly comparable. Beijing’s air is continuously improving, while Delhi’s pollution remains dangerously toxic.

The Indian capital’s pollution has reached a level equivalent to smoking 50 cigarettes a day. In recent days, the worst air in three years encapsulated Delhi, prompting a temporary ban on millions of private vehicles in the Indian capital and the shutdown of schools. This wasn’t a total surprise: Like every year, cooler temperatures and slower winds starting in October were expected to worsen air quality.

Similar weather conditions have long mired Beijing and other major cities, too.

Still, the Chinese capital’s air quality improvements have been stunning in recent years. In September, Swiss firm IQAir’s research group, AirVisual, said Beijing may even be on track to drop out of the list of the world’s 200 most polluted cities — more than a decade after it was branded “the air pollution capital of the world.” Small particulate concentrations in the Chinese capital have now dropped to their lowest level since they began to be monitored in 2008, according to IQAir.

Even though China’s air quality has deteriorated in some parts of the country over the past few years, the markedly divergent trends in Delhi and Beijing appear to reflect differences in the two governments’ ability to combat pollution.

Among the factors that are contributing to Delhi’s pollution are crop burnings in the proximity of Delhi — a traditional practice, especially in fall, but also during other seasons — that has once again picked up in recent weeks, according to satellite imagery. In the past, it has been found to account for 26 percent — and on some days as much as 50 percent — of the most harmful particulate matter in Delhi in winter, according to The Post’s Joanna Slater.

Not so in Beijing.

Burning of agricultural fields after harvest has long been popular as an easy way to prepare fields for the next crop. But Chinese authorities began to crack down on the practice more resolutely than in the past in 2015, after such fires contributed to an alarming spike in pollution and raised questions about authorities’ ability to force changes.

In a study published last year, a team of researchers found that the number of burning spots during fall had plummeted across China between 2015 and 2017. Overall, crop burning remained a pollution factor, however, as some farmers appear to have resorted to burning cropland during other seasons.

In comparison, India’s democratic government has struggled to confront the problem with the same efficiency as China’s authoritarian state. Farmers account for a significant share of Indian voters in some states, which has slowed the country’s response.

Fines are rarely enforced. Awareness campaigns or government funds for machinery that would allow farmers to process the straw into mulch have so far failed to have the desired impact, too.

Whereas Beijing has adopted a preventative approach on a number of fronts, experts remain concerned over the Indian government’s mostly reactive stance.

Beijing, for instance, has shuttered factories near the capital — with more closures expected to follow — and cracked down on diesel trucks.

Meanwhile, industrial emissions, vehicle exhaust and construction dust continue to pollute the air in and around Delhi. Even though the government has taken some measures, such as closing down a major coal-fired power plant last year, other steps, such as banning trucks, are implemented only once pollution gets too bad.



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