Smog peak may be worse this year: Study

Bathinda: The Centre for Science and Environment (CSE) has predicted that this winter may get a much severe peak in smog when compared to previous years.
This was concluded after CSE analysed air quality trends in Delhi and National Capital Region (NCR), besides the larger Indo-Gangetic Plain (IGP) region. “This winter, we may get a much severe peak in smog; farm stubble fire counts may get more concentrated due to the delayed effect of the rains. To counter this, action must be scaled up right away,” said Avikal Somvanshi, programme manager at urban data analytics lab at CSE.
Normally, the first phase of winter smog is triggered by largescale stubble burning. The contribution of farm stubble fire this year started roughly around October 10, the same time as in 2018 and 2020. Peak contribution this year so far was registered on October 16, when 14% of Delhi’s PM2.5 was attributed to stubble fire smoke. Heavy rains in the following days washed out the first build-up of the season. The smoke season generally peaks around the cusp of October and November, with contribution spiking to over 40% on the worst days, said Somvanshi.
In 2020, during the stubble burning season October 1-November 29, an average 12.2% per day of Delhi’s PM2.5 pollution came from farm stubble fire smoke. This was considerably higher than previous years. In 2019, contribution stood at 8.9% per day, while it was 10.9% per day in 2018.
The farm fire count during the pre-winter season of 2021 has been less than half of the number recorded last year. The lower count, as reported by satellite imagery, can also be due to increased cloud cover which hinders spotting of fires by satellites. Nevertheless, lower fire count during pre-winter correlates well with the lower pollution level in Delhi-NCR.
Tracking all the 67 monitored cities in the Indo Gangetic region makes it very clear that air quality dips to ‘poor’ and ‘worse’ categories as the monsoon retreats. For most of the northern plains from Punjab to central Uttar Pradesh, the start of bad air quality days is almost perfectly synchronised. Eastern plains witness the onset of pollution almost three-four weeks later. It is interesting to note that air cleans up in Punjab much earlier than in the rest of IGP, while pollution lingers on longer in NCR and adjoining western UP, the study said.