Delhi Pollution Study: Local Sources Main Contributor in Oct-Nov

Local factors dominate the air pollution of Delhi-NCR during October and November; Stubble burning has nothing to do with this study: Report
According to a new study released in the npj Climate and Atmospheric Science journal, the stubble burning of Punjab and Haryana had no impact on Delhi NCR during October-November but this indicates that local factors rather dominated pollution during these periods.

GRAP-4: The Sharpest Anti-Pollution Policy
GRAP is a series of measures that are aligned to constraint air pollution in relation to the level of air quality. The most stringent level, that is GRAP-4 comes into action once AQI crosses 450 that belongs to the 'severe plus' category. This includes restrictions in vehicular traffic, construction operations, and industrial activities.
Research Findings: Minimal Effect of Burning Stubble
Data for PM2.5 were collected by researchers under the Aakash Project of Research Institute for Humanity and Nature in Japan, from September 2022 to November of the same year and in 2023. The worth of around 30 units of air quality sensors was mounted at different sites in Punjab, Haryana, and Delhi-NCR to catch trends.

Despite widespread belief that stubble burning significantly worsens Delhi’s air quality, the study found that it contributed only 14% to PM2.5 levels in 2022. Moreover, satellite data showed that stubble burning incidents in Punjab and Haryana decreased by 50% between 2015 and 2023, yet Delhi’s pollution levels remained largely unchanged.

GRAP's Role in Pollution Control
The emissions are controlled and imply a change in the levels of PM2.5 in Delhi-NCR based on different GRAP measures. The most strict stage has shown the greatest improvement in the decrease of pollution because of emission control of road traffic, construction, and industrial activities by GRAP-4.
Again in both 2022 and 2023 once the restrictions enforced under GRAP-4 have been withdrawn the levels of PM2.5 again increased both years. Probably the local pollution sources are doing more damage in the air qualities than was first thought.

Intermittent measurements alone are no good. Regular observations are mandatory.
The report suggests monitoring of air quality in Punjab (source), Haryana (receptor region), and Delhi-NCR (receptor). The control policies would include the localized emissions and all foreign inputs.

Aakash Project
Aakash Project was started on April 1, 2020. It aims at bringing social change for cleaner air, improvement of public health, and appropriate agriculture in North India.
   
Conclusion
While stubble burning does contribute to pollution in Delhi, it is smaller in magnitude than what is assumed. Most direct reductions in PM2.5 come from the GRAP measures. This continues the case for local action against pollution.