New Delhi, Feb 4 (PTI) – A recent study has suggested that pollution levels in Delhi-NCR during October and November are primarily of local origin, with stubble burning in Punjab and Haryana contributing only 14% to the overall PM2.5 levels in 2022.
The research, led by experts from Japan's Research Institute for Humanity and Nature under the 'Aakash Project', highlights that air quality fluctuations in the national capital are more closely linked to the enforcement of the Graded Response Action Plan (GRAP) than to external pollution sources.
Published in the journal npj Climate and Atmospheric Science, the study analyzed PM2.5 levels recorded from September to November in 2022 and 2023. The researchers deployed 30 sensors across Punjab, Haryana, and Delhi-NCR to monitor pollution trends.
Further, the data showed that even as satellite-recorded stubble fire incidents in Punjab and Haryana dropped by at least 50% between 2015 and 2023, Delhi’s PM2.5 levels remained relatively stable. This suggests a weak correlation between farm fires and the capital's pollution levels.
The researchers found that PM2.5 levels in Delhi-NCR fluctuated in sync with the tightening or relaxation of GRAP measures. "The decline in PM2.5 levels was mainly attributed to GRAP-IV, which restricts emissions from road traffic, construction, and other sources. However, a resurgence in pollution was observed once GRAP-IV restrictions were lifted in both 2022 and 2023," the study noted.
"We have identified pollution patterns using a network of monitoring stations across Punjab, Haryana, and Delhi-NCR, enabling us to assess the impact of crop residue burning in weekly and monthly averages," explained Prabir Patra, leader of the Aakash Project and principal scientist at the Japan Agency for Marine-Earth Science and Technology.
The findings emphasize the need for stronger localized pollution control measures within Delhi-NCR, rather than an exclusive focus on farm fires, to effectively combat the region's deteriorating air quality.
The research, led by experts from Japan's Research Institute for Humanity and Nature under the 'Aakash Project', highlights that air quality fluctuations in the national capital are more closely linked to the enforcement of the Graded Response Action Plan (GRAP) than to external pollution sources.
Published in the journal npj Climate and Atmospheric Science, the study analyzed PM2.5 levels recorded from September to November in 2022 and 2023. The researchers deployed 30 sensors across Punjab, Haryana, and Delhi-NCR to monitor pollution trends.
Key Findings: Limited Impact of Stubble Burning
The common perception that stubble burning is the primary driver of Delhi-NCR’s winter pollution was challenged by the study. Despite being a widely criticized practice for its role in deteriorating air quality, emissions from stubble burning in Punjab contributed only around 14% to Delhi-NCR’s PM2.5 levels in October and November 2022.Further, the data showed that even as satellite-recorded stubble fire incidents in Punjab and Haryana dropped by at least 50% between 2015 and 2023, Delhi’s PM2.5 levels remained relatively stable. This suggests a weak correlation between farm fires and the capital's pollution levels.
GRAP Measures Play a Crucial Role
The study underscores the significant role of GRAP—a tiered anti-pollution measure introduced to curb emissions based on air quality severity. GRAP-IV, the most stringent level, is implemented when the Air Quality Index (AQI) surpasses 450, reaching the 'severe plus' category.The researchers found that PM2.5 levels in Delhi-NCR fluctuated in sync with the tightening or relaxation of GRAP measures. "The decline in PM2.5 levels was mainly attributed to GRAP-IV, which restricts emissions from road traffic, construction, and other sources. However, a resurgence in pollution was observed once GRAP-IV restrictions were lifted in both 2022 and 2023," the study noted.
A Data-Driven Approach to Pollution Control
By analyzing pollution trends across 30 monitoring sites, the researchers were able to separate the contributions of paddy straw burning from overall PM2.5 variations in Delhi."We have identified pollution patterns using a network of monitoring stations across Punjab, Haryana, and Delhi-NCR, enabling us to assess the impact of crop residue burning in weekly and monthly averages," explained Prabir Patra, leader of the Aakash Project and principal scientist at the Japan Agency for Marine-Earth Science and Technology.
The findings emphasize the need for stronger localized pollution control measures within Delhi-NCR, rather than an exclusive focus on farm fires, to effectively combat the region's deteriorating air quality.
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