PTI

New Delhi, December 12

The interval from October to November was the least polluted within the final eight years in Delhi and there was no extreme smog episode in the course of the winter season to date, in line with inexperienced suppose tank Centre for Science and Environment.

“Diwali in a warmer October, lower incidents of crop fires, pre-emptive action based on pollution forecasting, and favourable meteorological conditions including extended rainfall in October, have all contributed towards bending of the early winter pollution curve,” mentioned Anumita Roychowdhury, govt director, analysis and advocacy, CSE.

But there could also be extra spikes later as has often been noticed in earlier years. Stronger pre-emptive measures and deeper round-the-year motion on native sources is required to deliver down the winter air pollution to passable ranges, she mentioned.

The CSE evaluation is predicated on real-time information obtainable from purposeful air high quality monitoring stations in Delhi-NCR. There are 81 steady ambient air high quality monitoring stations (CAAQMS) unfold throughout the area.

The evaluation confirmed that common PM2.5 ranges throughout 37 purposeful CAAQMS stations in Delhi stood at 142 micrograms per cubic metre (µg/m3) for the months of October and November.

This is the bottom stage recorded for the reason that metropolis put in these stations in 2018.

“If data for the 10 oldest stations (working since 2014-15) is referred to, October-November of this year remains the least polluted in comparison,” the CSE mentioned.

The PM2.5 stage this October-November has been 38 per cent decrease as in comparison with October-November of 2016, which was the worst within the final eight years.

Ghaziabad’s October-November common PM2.5 this 12 months is 36 per cent decrease than the identical interval in 2020. Similarly, Greater Noida and Faridabad registered enhancements of 28 per cent and 22 per cent, respectively. This is larger than Delhi’s city-wide enchancment of 19 per cent in the identical time-frame.

Gurugram confirmed the least enchancment with a mere 15 per cent change.

Noida’s October-November common PM2.5 this 12 months seems to be 40 per cent decrease than the identical interval in 2020.

However, it might be famous that one in every of Noida’s CAAQM stations is reporting uncharacteristically low values this season. This must be examined, the CSE mentioned.

Delhi was probably the most polluted main metropolis in NCR with an October-November common of 142 µg/m3, adopted by Gurugram (134 µg/m3) and Ghaziabad (131 µg/m3).

The CSE evaluation additionally confirmed that there was no extreme smog episode to date throughout this season.

This makes the October-November interval the primary within the final 5 years to be smog-free.

It is taken into account a extreme smog episode when the air high quality index stays within the ‘severe’ class for a minimum of three consecutive days.

There is often one smog episode throughout October-November lasting six-ten days.

During the winter of 2021, there have been three smog episodes – two in November and one in December. November 2021 had recorded the longest smog episode of 10 steady days (4-13 November). Such occasions haven’t occurred this winter.

Farm fires this 12 months have been about half of the earlier 12 months. The complete rely of farm fires reported this 12 months from Punjab, Haryana and Delhi within the months of October and November stood at 54,391, in line with NASA’s VIIRS satellite tv for pc and 11,824 in line with NASA’s MODIS satellite tv for pc.

These are respectively 37 per cent and 42 per cent decrease than the figures for October-November of 2021.

Analysis of SAFAR information reveals that this 12 months, smoke from the farm fires contributed to PM2.5 ranges in Delhi on 53 days, beginning October 12 and ending on December 3. This is lower than the final three years, when smoke intrusion was reported on 56 days however larger than the 2018 determine of 48 days. The highest contribution this 12 months was 34 per cent, reported on November 3.

The smoke from farm fires that covers Delhi relies on two main components: quantity and depth of the fires, and meteorological situations conducive for transportation of the smoke to Delhi.

This October-November, not solely the quantity and depth of farm stubble fires have been comparatively decrease but in addition the meteorological situations have been much less conducive for the transport of smoke.

As a end result, significantly lesser smoke invaded Delhi.

The CSE estimated that smoke contributed about 4.1 tonnes of PM2.5 throughout October-November in Delhi. This is 37 per cent lesser than the 6.4 tonnes that got here final 12 months, and in addition nearly half of the 2020 determine.

High rainfall and native wind velocity helped disperse native air pollution.

Delhi acquired 115 mm of rainfall this October-November, the very best within the final 5 years. This helped clear up the town air, particularly in October.

Average wind velocity for November stood at 12.4 km/hour which helped in dispersing native air pollution. Average wind velocity for the month in 2021 was 11 km/hour and 11.5 km/hour in 2020.