After enjoying a few rare days of clean air earlier this year, Delhi’s air quality worsened in September. Most days stayed in the ‘moderate’ category, and the air improved only during short spells of rain, when showers and strong southeasterly winds helped clear the pollution for a while.
Changing Air Quality in September
September marks a turning point for Delhi’s air. The relatively clean post-monsoon air starts getting polluted again, signaling the beginning of the city’s annual “pollution season.” While August saw some ‘good’ AQI days, September mostly brought ‘moderate’ air quality. On some days, pollution levels spiked sharply even if the overall trend was gradual.
Data from the Central Pollution Control Board (CPCB) shows that these ups and downs in air quality are closely linked to weather changes. The Daily Jagran spoke to Aakiz Farooq, Climate and Energy Campaigner at Greenpeace India, to understand what’s behind these AQI trends and what can be done to stop the air from worsening.
AQI in September 2025
For the first time since 2016, Delhi recorded 18 straight days of ‘moderate’ air quality in September.
What the AQI Data Shows
Early to Mid-September:
The start of the month was relatively better. Thanks to the monsoon, occasional rain and strong winds helped clear out pollutants, keeping the air mostly ‘satisfactory.’
Mid to Late September:
As rainfall decreased and wind patterns changed, pollution levels started to rise. The air quality moved from ‘moderate’ to ‘poor’ on several days.
Why Is Air Pollution Rising?
Aakiz Farooq explained that during the monsoon, rain helps wash away dust and emissions. But as rainfall reduces by the end of September, pollutants remain trapped in the air.
“In Delhi, a lot of pollution comes from vehicles releasing nitrogen oxides. Traffic emissions are one of the biggest reasons for the city’s rising air pollution,” he said.
Warning Ahead
October began with air quality in the ‘satisfactory’ range, but September’s data shows that pollution is already creeping up. This is a warning sign for both citizens and the government to take early action before the heavy smog settles over the city once again.
