A prolonged spell of rain in early October gave Delhi its second-best air quality in the month since 2015, when the Central Pollution Control Board started maintaining air quality index data.
The capital recorded an average air quality index of 210, the best in the month after the average AQI of 173 recorded in October last year.
The average AQI stood at 265 in 2020, 234 in 2019, 268 in 2018, 285 in 2017, 271 in 2016 and 264 in 2015.
"Air quality deterioration is seasonal in our country. This is because of the intrusion of dust from neighbouring countries. Low wind speed leads to accumulation of pollutants. Stubble burning, excessive use of vehicles and construction work aid in accumulation of pollutants.
"Implementation of the Graded Response Action Plan would surely reduce pollution levels," said Dipankar Saha, former chief of CPCB's air lab.
The city recorded two 'good' air quality days, the highest in eight years, and four 'satisfactory' days in October owing to bountiful rainfall.
On October 10, Delhi recorded a 24-hour average AQI of 44, the best since August 31, 2020.
The city did not record any 'good' air quality day in October from 2015 to 2020.
Delhi logged 128.2 mm of rainfall this month, the highest for October since 1956. The rainfall suppressed farm fires and kept the air clean till October 15.
However, pollution levels rebounded amid unfavourable meteorological conditions in the second half of the month. Emissions from firecrackers and stubble burning pushed the air quality in the 'very poor' category on Diwali.
The AQI has largely remained in the 'very poor' zone since then.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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