By Adam Vaughan
A severe episode of smog blanketing large parts of northern India has forced authorities to impose traffic restrictions, cancel dozens of flights and close primary schools.
Levels of tiny particulate pollution, PM2.5, spiked over the weekend to more than ten times the safety limit in the capital, Delhi. Residents took to social media to report difficulties breathing and post footage of views obscured by grey smog.
Such extreme pollution events happen every year in the region, usually between October and November, driven by weakening winds, falling temperatures and the seasonal impact of farmers burning the stubble of crops.
“You can almost count on something of this magnitude happening,” says Joshua Apte at the University of Texas at Austin. The current crisis is not even the worst India has suffered: in 2016, Delhi was hit by dangerous smog for almost a week.
The single biggest cause of pollution in Delhi on Monday was agricultural fires – 38 per cent of the contribution – according to modelling by Indian air quality researcher Sarath Guttikunda.
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But Apte says it would be wrong to lay the blame primarily on farmers, because other sources – including road dust, vehicle emissions, industry, power plants and households burning wood for heat and cooking – are also a major problem and are easier to tackle. “Even on a good day the air in north India is among the most severely polluted on the planet,” he says.
The scale of the problem goes far beyond Delhi, says Pallavi Pant at the Health Effects Institute in Boston, Massachusetts. “There are smaller towns and villages across the northern part of the country that are facing equally dire pollution.”
In the short term, there is little to be done short of waiting for winds to shift the smog. Authorities are limiting drivers’ access to Delhi based on whether they have an odd or even number plate. But that alone is not going to solve the problem, partly because vehicles are not even the biggest source of emissions and partly because some vehicles are exempt, says Pant.
In the longer term, both Apte and Pant say India has to implement stronger pollution controls across a range of sectors, and at both the local and regional level.
Delhi is the 11th worst city in the world for annual PM2.5 levels, according to the World Health Organization, which says almost half of the planet’s 50 most polluted cities are in India. Part of the country’s problem with tackling the issue appears to be senior public figures denying the health impacts of dirty air. One minister even tweeted on Sunday that eating carrots could reduce the health impacts of pollution.
“If these types of episodes are happening every single year, what that speaks to you is that the policy process around air pollution in India is evidently broken,” says Apte.
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