Delhi recorded only one ‘Good’ air quality day during the entire 92-day monsoon season, according to an analysis by the Centre for Science and Environment (CSE). This occurred on July 9, 2026, when rainfall was 67.75 mm. Despite heavy precipitation, baseline pollution remained elevated, with particulate matter (PM2.5) rebounding within 48 hours of rainfall.
During the monsoon, PM2.5 levels dropped to 32.7 μg/m³ during rain but rebounded to 45.1 μg/m³ within 48 hours, exceeding the pre-rain baseline. The monsoon seasonal average PM2.5 concentration was 40.2 μg/m³. Researchers noted that while rain temporarily reduces PM2.5, unaddressed anthropogenic emissions cause pollution levels to rise quickly.
During the summer months (April-May 2026), there were no ‘Good’ air quality days. The monsoon season saw a significant decrease in ‘Poor’ air quality days (3.3%) compared to summer (27.9%), but ‘Moderate’ days remained the largest share at 57.6%. CSE stated that sustained, year-round emission reductions are necessary for clean air, as relying on seasonal weather or temporary winter interventions is insufficient.
Source: Down To Earth