Undeniable role of crop residue burning (CRB) in the rural air pollution increase
image: Air pollution build up in New Delhi area every year since the early October. The line of sight in this photo shows large number of suspended particles in air on 3rd October 2024.
Credit: Aakash Project, RIHN
Severe air pollution is a chronic issue in the Indo-Gangetic Plains during harvest time (generally post monsoon Oct-Nov) this year. A large amount of rice straw is burned after the Kharif crop season in northwest India. In the RIHN news on 08 Nov 2023, we stated that “As a community, we must address all causes of air pollution and not subjugate agricultural community only.” However, the Indian newspapers are mainly reporting each fire occurrence and count, hence bringing it to the knowledge of the government officials for penalizing the farmers. The Supreme Court of India (SCI) has summoned the Chief Secretaries of Punjab and Haryana over non-compliance of ‘zero’ rice stubble burning (e.g., The Telegraph, 16 Oct 2024, Stubble burning: SC raps Punjab, Haryana govt over non-compliance, summons Chief Secretaries). Clearly, efforts to achieve zero stubble burning are needed for maintaining healthy air quality in the rural and adjacent areas (Singh et al., 2023; V. Sivaraman, Newsclick, 23 Oct 2023); but imposing instructions to suddenly stop conventional practices arising from modern-mechanised and intensified agriculture could be unfair on the farming community.
However, governments have released guidelines well in advance on Crop Residue Management (CRM) and emphasized integration of ex-situ management and supply chains for industries to utilize crop residue for biomass power generation, co-firing in thermal power plants, Bio-CNG and Bio-Ethanol production, etc. (Crop Residue Management Operational Guidelines, March 2024). A CRM loan scheme or financial assistances, where 50-80% subsidies on CRM machineries, are offered to empower farmers by facilitating access to disposal equipment. These incentives have been popularised by the Chief Minister of Punjab (Business Standard, 06 Oct 2024), demonstrating efforts at various government levels towards achieving zero stubble burning by expanding sustainable farming practices. Additionally, there is a lot to be done in and around the Delhi-National Capital Region (NCR) to control air and water pollution which are purely from industrial activities (The Statesman, 19 Oct 2024; As winter approaches, Delhi’s air quality worsens to ‘Very Poor’; Yamuna covered in froth), but the blame-game continues as Mr. V. Sivaraman wrote in his 2023 article.
Since 2022, a group of International Collaborators led by the Research Institute for Humanity and Nature (RIHN), Tokyo, Japan, have conducted field campaign in the regions of Punjab, Haryana, and Delhi-NCR (Singh et al., 2023; RIHN press release on 2nd Oct 2023). A network of about 30 low-cost Compact and Useful PM2.5 Instrument with Gas sensors (CUPI-Gs) has been established in the region for 2024 as well. These measurements have, for the first time, provided a wholesome picture of month-long CRB activities in the source regions and their contribution to the limited number of high PM2.5 events over Delhi-NCR. The continuous measurements of source pollutants directly emitted from CRB, such as particulate matter of aerodynamic radius of 2.5 micrometer (PM2.5) and carbon monoxide (CO) enables tracking of the CRB activities in the surroundings of our measurement sites. When data is stitched together for 30 sites, the CUPI-G measurements allow us to study the regional characteristics of the air pollutant emissions and movements in the region. With these observations, we can associate a reduction in fire detection counts from satellites in Punjab and Haryana in 2023, compared to those in 2022, with a reduction in PM2.5 in the regions of CRB (Mangaraj et al., in review).
Air pollution flows from higher to lower concentration areas in the direction of the winds. So far (during 12-18 October), 2024 has seen an unprecedented rise in PM2.5 values in the regions of Punjab, Haryana, and Delhi-NCR (Fig. 1). This is because 2024 experienced reduced rain and slowed winds of all 3 years, as evident from Fig. 1. The significant role of reduced winds in accumulation of PM2.5 in Delhi-NCR during Oct-Nov 2023 had been established by comparing with the CUPI-G measurements between 2022 and 2023, and this meteorological impedance under the assumptions that the emissions from Delhi-NCR did not differ much between the two years (Mangaraj et al., in review). We also find early fire occurrences in the Pakistan side of Punjab, while the Indian side is observing low fire counts, as expected from the strict government regulations on crop residue burning. However, we have observed a large amount of cross-border transport of air pollutants in 2022 and 2023 when the CRB intensifies in Punjab, India, during the late Oct and the first half of Nov. The northwest Haryana also shows greater fire detections in 2024 compared to the previous years. Due to proximity, CRB in Haryana has greater effects on PM2.5 in Delhi-NCR compared to CRB in Punjab.
At this early stage it remains to be seen how the air pollution conditions unfold over the next 4 weeks. We expect large reductions in air pollution in the rural areas of Punjab and Haryana as a result of the drastic implementation of a zero residue burning policy, if maintained till the end of Nov. The urban areas may observe air pollution levels at similar levels, like in previous years, as no drastic policy implementations have been made. The effect of the Graded Response Action Plan (GRAP) by the Commission for Air Quality Management (CAQM) brought successes, but limited, in the reduction of air pollutants in Delhi-NCR while largely controlling the air pollution to rise further from the date of implementation of the most stringent GRAP Stage IV.
Aakash Project at the RIHN, Kyoto, Japan, is working closely with Indian counterparts to address the issue of "An Interdisciplinary Study toward Clean Air, Public Health and Sustainable Agriculture: The Case of Crop Residue Burning in North India". A large number of scientists from India and Japan work, mostly voluntary, to progress research on air pollution in the northwest India region. We will continue the CUPI-G measurements through the Diwali festival and the end of the CRB season. Periodical updates based on the observations will be prepared and shared online from the RIHN website.
(Prabir Patra, Yutaka Matsumi, Takayuki Yamasaki, Hikaru Araki, Akash Biswal, Tomoki Nakayama, Poonam Mangaraj, Natsuko Yasutomi)
Reference:
Mangaraj et al., in review, Weak coupling of observed surface PM2.5 in Delhi-NCR with rice crop residue burning in Punjab and Haryana, 23 July 2024, PREPRINT (Version 1) available at Research Square.
RIHN news, Very high air pollution event on 2-5 Nov 2023 in Delhi NCR couldn’t be explained by crop residue burning, 08 Nov 2023.
RIHN press release, Dense measurement network revealed high level of PM2.5 in Punjab due to crop residue burning and its transport to Haryana and Delhi NCR. 02 October 2023.
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The Research Institute for Humanity and Nature (RIHN) is a national institute established in Kyoto in 2001. RIHN aims, through research that integrates the humanities and sciences, to address environmental issues concerning the relationship between "humanity" and "nature" in a broad sense as fundamental issues of human culture. We strive not only to engage the research community but also to collaborate with diverse stakeholders in society, including local residents, to find solutions to global environmental problems.
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