Average PM 2.5 worst in 5 years, but winter peak down, says CSE study

Last Updated08/11/2024

A low-hanging yellow haze, characteristic of the days after Diwali in Delhi, has mostly been missing this year. The city’s air has not yet entered the ‘severe’ zone, where the Air Quality Index (AQI) crosses the 400 mark.

This year, Delhi's familiar post-Diwali haze has been less severe, with the Air Quality Index (AQI) not reaching the "severe" level (over 400). However, new findings reveal a nuanced picture:
Lower PM 2.5 Peaks, Higher Averages: According to the Centre for Science and Environment (CSE), peak Particulate Matter 2.5 (PM 2.5) levels in winter have dropped by 35% compared to 2019-20. Yet, the average daily PM 2.5 concentration has risen, indicating a persistent level of pollution rather than extreme peaks.

Local Emissions as Key Contributors: The rise in daily pollution levels suggests that local sources, particularly vehicular emissions, significantly impact air quality.

Vehicular Emissions: Account for over 50% of local pollution sources and remain the top contributor.
Stubble Burning: Surprisingly contributes only 8.19% to Delhi's overall pollution levels, much lower than previously perceived.

High Winter Averages, Declining Annual Averages: While winter PM 2.5 levels are at a five-year high (189 µg/m³), the annual PM 2.5 levels have dropped by 7% since 2019. To meet National Ambient Air Quality Standards, Delhi still requires a further 60% reduction in PM 2.5.

The CSE analysis identifies sources of pollution affecting Delhi as follows:
- Delhi’s Local Sources: 30.34%, with over half coming from transportation.
- Neighboring NCR Regions: 34.97%.
- Other Regions: 27.94%.

Delhi’s evolving air quality profile underlines the need for immediate action on vehicular emissions and other local pollution sources. While the reduction in extreme pollution peaks is promising, consistent daily pollution remains a pressing issue.