An extended monsoon season and record-breaking rainfall in October gave Delhi its best air quality in the month in four years, according to data from the Central Pollution Control Board (CPCB).
This is also the first time in four years that Delhi did not see a single "very poor" or "severe" air quality day in October which generally records a sharp rise in pollution levels due to unfavourable meteorological conditions and stubble burning in the northwest region of the capital.
The capital recorded a "good" air day in October this year, also a first in four years.
An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe"
Delhi gauged 122.5 mm of rainfall in October, the highest in the month since 236.2 mm of precipitation recorded in 1956, according to the India Meteorological Department.
Stubble burning and its share in Delhi's PM2.5 pollution also remained low due to heavy rain.
According to data from the Indian Agricultural Research Institute, Punjab has recorded 10,374 farm fires this season since September 15 as compared to 29,712 stubble burning incidents in the corresponding period last year.
The city recorded an average air quality index of 173 in October this year, the lowest in the month in four years.
October saw an average AQI of 265 in 2020; 234 in 2019 and 264 in 2018.
The CPCB data showed the city witnessed three "satisfactory" air quality days in October this year as compared to zero in 2020, four in 2019 and nil in 2018.
The capital also saw 19 "moderate" air quality days as against six such days each in 2020, 2019 and 2018.
Eight "poor" air quality days this month was the lowest in October since 2018.
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