Stubble burning in Punjab doubles Delhi pollution: Harvard study
BOSTON: Agricultural fires are to blame for about half of the pollution experienced in Delhi in October and November, peak stubble burning season in Punjab, a Harvard study has found using satellite data from NASA.
Many farmers in northwest India typically burn abundant crop residue on the fields after harvest season, to prepare their fields for subsequent planting.
To what extent the smoke emitted by these fires contributes to Delhi’s pollution has been a burning question.
While crop burning has been illegal for years, there has not been a large enough deterrent to effectively crack down on the practice — in part because it has been difficult to measure exactly how much smoke from the fires is making it downwind to the city.
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On certain days during peak fire season, air pollution in Delhi is about 20 times higher than the threshold for safe air as defined by the WHO
DANIEL H CUSWORTH, a graduate student at SEAS, Harvard
Researchers from the Harvard University and NASA have now shown that in October and November, peak burning season in Punjab, about half of all pollution in Delhi can be attributed to agricultural fires on some days.
“On certain days during peak fire season, air pollution in Delhi is about 20 times higher than the threshold for safe air as defined by the World Health Organization (WHO),” said Daniel H Cusworth, a graduate student at SEAS and The study, published in the journal Environmental Research Letters, used satellite data from NASA to identify hotspots corresponding to active fires.
The team gathered available data for October and November, 2012 to 2016 and plugged it into a particle dispersion model — an algorithm that accounts for geography, wind patterns, and physics to predict how far and in what direction smoke particles travel.
On average, without fires, urban Delhi experiences about 150 microgrammes per cubic metre of fine particulate air pollution.
To put that into perspective, the WHO puts the threshold for safe air at 25 microgrammes per cubic metre, and India’s Central Pollution Control Board limits exposure to 60 microgrammes per cubic metre, said Cusworth.