Half of the pollution experienced in Delhi during October and November could be attributed to Agricultural fires in the nearby states, researchers at Harvard have found.
For the past few years, every autumn the national capital —already thick with pollution—gets engulfed with choking smoke, thanks to the large-scale stubble burning in the surrounding areas. Last year, Delhi chief minister Arvind Kejriwal likened the city to “a gas chamber.”
To analyse how much of that pollution is coming from the fires, the researchers used satellite data from NASA to identify hotspots corresponding to active fires.
The team collected 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, PTI reported.
Indian Express
Even without fires, urban Delhi, on average, experiences about 150 microgrammes per cubic metre of fine particulate air pollution, six times higher than WHO’s threshold for safe air set 25 mg per cubic metre.
However, during stubble burning season, air pollution in Delhi soars 20 times higher than the threshold level.
After monsoon, the air in northern India is particularly stagnant, which means smoke particles do not vent into the atmosphere as they would during other times of the year. Around this time, many farmers in northwest India, set fires to their fields to clear stubble after the harvest, in order to prepare their fields for subsequent planting.
This happens year after year despite a ban on the practise. So far, there has not been any large scale crackdown on stubble burning because it’s been difficult to assess how much smoke from the fires is making it downwind to the city.
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