Studies call for regional approach to tackle air pollution

Updated November 09, 2019

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Nasa's data shows heavy concentration of fires on Indian side and far fewer on Pakistani side of the border. — AFP/File
Nasa's data shows heavy concentration of fires on Indian side and far fewer on Pakistani side of the border. — AFP/File

WASHINGTON: There has been a dramatic increase in stubble burning in the Indian states of Punjab and Haryana, which is causing an equally dramatic increase in air pollution across the region, says a report released by the US space agency, the National Aeronautics and Space Administration (Nasa).

Nasa collected data from Oct 21 to 29 and has also released satellite images of fires, showing a heavy concentration of fires on the Indian side and far fewer on the Pakistani side of the border.

Another report by the Indian Ministry of Earth Sciences’ air monitor, SAFAR, says that the share of stubble burning in Delhi’s pollution rose to 35 per cent on Wednesday, the season’s highest.

A BBC report pointed out that since Lahore is some 20km from India’s border, “so it could easily be affected by smoke from across the border”.

Nasa’s Aqua satellite passed over north-western India and north-eastern Pakistan on Oct 10, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) on board to acquire a true-colour image of a number of fires burning in the region. “Given the time of year and location of the fires, these almost certainly have been set to manage the land for agriculture,” Nasa reported.

The region has two growing seasons — from May to September and November to April. In November, farmers sow crops such as wheat and vegetables; but before they do that, farmers often set fields on fire to clear the stubble and prepare them for cultivation.

Statistics released by India’s Punjab state government show that there were 42,676 fires between Sept 23 and Nov 6 — more than during the entire season both in 2018 and 2017.

Various reports also point out that the burning contributes to air pollution both within each country and across their shared border, but the intensity of the impact varies from season to season.

In autumn and early winter, the wind blows from south to south-east, which would take the pollution into India, not Pakistan. But a recent study, by the US Rand Corporation, says this can change from year to year, “depending on prevailing wind patterns and the timing of the field burning”.

Rand Corporation notes that in the pre-monsoon burning season — April to May — fire activity is observed in both Indian and Pakistani Punjab. But in the post-monsoon burning season — October to November — when pollution levels are highest, it’s almost entirely concentrated in India’s Punjab region.

The report suggests additional scientific analyses to explore the complex dynamics associated with trans-boundary impacts of air pollution. “New, higher-resolution remote sensing datasets should be incorporated to capture the contributions of crop residue burning on smaller farms,” the report adds.

Another study by Liji M. David of Colorado State University and his co-author A.R. Ravishankara suggests that emissions in India are messing up air quality in the entire region.

The study notes that the subcontinent is home to 1.7 billion people, with more than one billion living in nonurban areas and air pollution in such a densely populated region could have devastating consequences.

The report warns that “more than a million Indians will die prematurely” each year from long-term ozone exposure by 2050.

The study used a chemical transport model to estimate the flow of boundary layer ozone and its precursors from eight regions within the subcontinent.

The study shows that Indo-Gangetic Plain and Central India are significant boundary layer ozone contributors to the neighbouring regions as well as eastern (including Bangladesh) and southern India. Emissions from Pakistan also affect the neighbouring areas.

The study also shows that most of the regions in the subcontinent cannot independently control their boundary layer ozone and urges a regional approach to deal with this issue.

Published in Dawn, November 9th, 2019