Air pollution spikes and health risks resulting from wheat crop residue burning in central India

INTRODUCTION

Agricultural residue burning is a widespread practice in India, especially in states such as Punjab, Haryana, Uttar Pradesh, and Madhya Pradesh.^[1] After the wheat harvest, farmers burn crop residues to prepare the land for the next sowing season.^[2]

In central India, wheat is one of the most widely cultivated crops, and the burning of crop residues significantly contributes to short-term spikes in air pollution.^[3] This practice is linked to increased concentrations of harmful pollutants in the atmosphere, posing serious health risks to local populations. Recent studies have highlighted the detrimental health impacts of these short-term pollution events, particularly concerning respiratory and cardiovascular diseases.^[4-7] These pollutants are known to irritate the lungs and worsen pre-existing health conditions, with vulnerable groups such as children, the elderly, and individuals with chronic illnesses at heightened risk.^[8,9] Figure 1 illustrates the common causes and consequences of crop residue burning in India, while Figure 2 presents the available alternatives to this practice. Most previous studies have predominantly focused on northern India, highlighting a significant knowledge gap as compared with other regions. This review article aims to address this gap by examining the health risks associated with increased air pollution from wheat crop residue burning in central India, with particular emphasis on exposure to particulate matter and gaseous pollutants.

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Figure 1:

Causes and effects of crop residue burning in India.

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Figure 2:

Various alternatives to crop residue burning in India.

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WHEAT PRODUCTION TRENDS IN INDIA

The year-wise wheat production in India from 1951-52 to 2021-22 shows a significant increase in total production over the decades [Figure 3]. The data reveals a steady rise in wheat production, from 6 million tons in 1951-52 to 109.59 million tons in 2020-21. Early years exhibit moderate growth, with production gradually rising above 10 million tons in the late 1950s. The most rapid increases occurred in the 1970s and 1980s, coinciding with the Green Revolution, which significantly boosted yields. By the 2000s and 2010s, India consistently produced over 70 million tons, peaking at 109.59 million tons in 2020-21.^[10] However, there were fluctuations, especially around the early 2000s and 2014-15, when production slightly dropped, possibly due to climatic factors or changes in agricultural policies. The remarkable growth in wheat production from the 1960s onward was driven largely by technological advancements and the Green Revolution [Figure 3].

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Figure 3:

Year-wise wheat production in India.

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The Green Revolution, initiated in the 1960s, introduced high-yielding varieties of wheat, increased fertilizer use, and improved irrigation methods, leading to significant productivity gains.^[11] Wheat production also benefited from the establishment of more efficient agricultural infrastructure, including improved access to credit and market systems. The peak production in 2020-21 underscores the success of these efforts, although periodic fluctuations such as in 2014-15 demonstrate the vulnerability of wheat production to factors like droughts, floods, and changes in government policies.^[12-14] Continuing challenges, such as water scarcity and soil degradation, may threaten long-term sustainability unless integrated and sustainable farming practices are further promoted.^[15,16] The future of wheat production in India depends on adapting to these challenges while maintaining productivity through technological innovations and efficient resource management.

WHEAT PRODUCTION IN CENTRAL INDIA

Wheat production in central India is vital for the region’s agricultural economy and plays a crucial role in food security and the livelihoods of millions of farmers.^[17] The region, including states like Madhya Pradesh, Maharashtra, and Chhattisgarh, has seen significant growth in wheat production over the past few decades, due to improved farming practices, high-yielding varieties, and better irrigation techniques.^[18] Madhya Pradesh, in particular, has become one of the leading wheat producers in India, with wheat covering a large portion of the state’s total agricultural area.^[19] The primary wheat-growing season occurs during the rabi cycle (winter), with sowing between November and December and harvesting from March to May. Access to irrigation from canals and groundwater has supported wheat cultivation, even in the region’s semi-arid climate.^[20] However, challenges such as erratic rainfall, soil fertility decline, and increasing pest problems threaten the sustainability of wheat production.^[21] Additionally, post-harvest crop residue burning has become an environmental concern, contributing to air pollution and degrading soil health.^[22-24] Despite these challenges, wheat remains a crucial crop in central India, and ongoing research into agronomic practices and climate resilience continues to shape its future.

TRENDS IN WHEAT PRODUCTION IN MAJOR STATES

The annual wheat production (in million tons) for the three major wheat-producing states in India, viz., Uttar Pradesh, Madhya Pradesh, and Punjab, from 2013 to 2023 has been presented in Figure 4.

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Figure 4:

Year-wise wheat production in top three states of India.

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The data reveals fluctuating trends in wheat production across these states, with Uttar Pradesh consistently being the highest producer, followed by Madhya Pradesh and Punjab. Over the period, Uttar Pradesh’s wheat production shows a steady increase from 29.89 million tons in 2013-14 to 35.51 million tons in 2020-21, before slightly declining to 33.61 million tons in 2022-23.^[10] Madhya Pradesh also demonstrates an upward trend, reaching its peak in 2021-22 at 22.98 million tons, while Punjab’s production fluctuates but generally declines from 17.62 million tons in 2013-14 to 14.86 million tons in 2021-22, before slightly increasing in 2022-23. These trends highlight significant regional differences in wheat production. Uttar Pradesh has maintained its dominance in wheat production due to favorable agricultural practices, irrigation facilities, and government support, aligning with improvements in mechanization and agricultural techniques.^[25] Madhya Pradesh’s production shows a remarkable increase, especially in recent years, indicating the successful adoption of high-yielding varieties, better irrigation infrastructure, and effective implementation of government schemes.^[19,20] Punjab’s declining wheat production can be attributed to factors such as soil degradation, water scarcity, and over-reliance on traditional farming practices, which are less sustainable in the long term.^[26-28] Overall, while Uttar Pradesh and Madhya Pradesh have seen steady increases, the challenges faced by Punjab underscore the importance of sustainable agricultural practices to maintain and enhance wheat productivity in India.

CROP RESIDUE GENERATION AND BURNING TRENDS IN INDIA

The trends in crop residue generation and crop residue burning in India from 1950-51 to 2017-18 have been presented in Figure 5.^[29-31]

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Figure 5:

Trends in crop residue generation and crop residue burning in India.

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The data reveals a clear upward trend in both crop residue generation and burning over the years. Crop residue generation increased from 80 thousand gigagrams (Gg) in 1950-51 to 517 thousand Gg in 2017-18. Similarly, crop residue burning grew from 18 thousand Gg in 1950-51 to 116 thousand Gg in 2017-18, reflecting increased reliance on burning as a method of residue disposal. This suggests that while crop production has increased, the management of crop residues, particularly through burning, has become more prevalent and potentially more harmful to the environment. The rising generation of crop residues is a direct result of the intensification of agricultural practices, including higher crop yields and the use of advanced farming technologies.^[32,33] However, the rise in crop residue burning is a significant environmental concern, contributing to air pollution, greenhouse gas emissions, and soil degradation.^[34] While burning offers farmers a quick and inexpensive way to manage crop residues, it is also linked to severe health hazards due to the emission of particulate matter and toxins.^[2,35] The increase in burning from 1950 to 2017 is particularly concerning in states like Punjab and Haryana, where large-scale stubble burning during harvest seasons is common.^[36,37] Efforts to address this issue include promoting alternative residue management practices, such as composting and using crop residues for bioenergy production.^[38,39] Nonetheless, balancing crop residue disposal methods with sustainable farming practices remains a challenge.

Between 2017 and 2024, India witnessed significant fluctuations in crop residue generation and burning, shaped by changing agricultural practices, evolving policy measures, and varying environmental conditions. By 2020, emissions from crop residue burning had surged by approximately 75% since 2011, reaching an estimated 33,834 Gg of CO₂-equivalent annually. In response, several state governments intensified their efforts to curb stubble burning through awareness campaigns and the promotion of alternative management techniques. Uttar Pradesh, for example, saw a 65% reduction in stubble burning cases from 8,784 in 2017 to 3,017 in 2022, largely due to improved outreach and support for sustainable farming methods. Similarly, Punjab reported a 26% decline in such incidents between 2022 and 2023, aided by the deployment of over 23,000 crop residue management machines. Despite these improvements, the issue remains far from resolved. In 2024, Punjab aimed to manage 19.5 million tonnes (MT) of crop residue, with 15.86 MT addressed through in-situ and ex-situ approaches. This underscores the continuing need for comprehensive and scalable residue management strategies. The Supreme Court of India, in a strong statement in October 2024, called for stricter enforcement and enhanced policy implementation, highlighting the gaps in current efforts. Overall, while certain regions have made measurable progress in reducing crop residue burning, the practice persists due to systemic barriers such as limited infrastructure, economic constraints, and inconsistent enforcement. Moving forward, coordinated efforts that combine technological support, financial incentives, and regulatory enforcement will be critical to addressing the environmental and public health challenges associated with crop residue burning in India.

WHEAT RESIDUE BURNING AND AIR POLLUTION IN CENTRAL INDIA

Wheat residue burning, traditionally more common in North India, is increasingly prevalent in Central India, particularly in major wheat-producing states such as Madhya Pradesh, Maharashtra, and Chhattisgarh, driven by the steady rise in wheat cultivation and production in these regions [Figure 2]. After the wheat harvest, farmers burn crop residues to quickly prepare the land for the next planting cycle. This practice has been increasing due to the pressures of intensive farming and a lack of effective alternatives for residue management.^[40] Studies estimate that around 25-30% of total crop residues in Central India are burned annually, with wheat residue burning alone contributing approximately 177,046.73 Gg/year of CO₂, 10,751.33 Gg/year of CO, 315.51 Gg/year of CH₄, 8.18 Gg/year of N₂O, and 292.15 Gg/year of NOₓ. This large-scale emission of greenhouse gases and pollutants significantly exacerbates air pollution and environmental degradation in the region.^[41] The increasing mechanization of agriculture, which leaves behind large quantities of residue that are difficult to manage, has intensified this trend.^[2] The burning of wheat residues releases pollutants, including particulate matter (PM2.5 and PM10), carbon monoxide (CO), and nitrogen oxides (NOx), which severely impact air quality and public health, particularly in urban and rural areas.^[37,42] Despite the negative effects, alternative residue management techniques such as mulching, composting, or using machinery like the Happy Seeder remain underutilized due to economic constraints and a lack of awareness among farmers.^[43,44] Addressing wheat residue burning is critical for reducing air pollution and promoting sustainable agricultural practices in central India.

Wheat crop residue burning trends in Central India are less widespread compared to Northern India, where the practice is most prevalent. In states like Punjab, Haryana, and Western Uttar Pradesh, wheat residue burning is driven by the rice-wheat cropping system and mechanized harvesting, with little time between wheat harvest and rice sowing to manage stubble through other means. In Central India, particularly in Madhya Pradesh, Chhattisgarh, and parts of Maharashtra, wheat production is becoming increasingly intensive. With the growing adoption of mechanized harvesting, farmers are more inclined to resort to residue burning as a quick and cost-effective method to prepare fields for the next cropping cycle. While wheat residue burning is less common in Eastern, Western, and Southern India, where wheat is either grown on a smaller scale or not at all, crop residue burning in general remains a concern, especially with rice stubble in some regions. Overall, while North India remains the epicenter of wheat residue burning, Central India is experiencing a rise in this practice as wheat cultivation expands, emphasizing the need for alternative management practices to mitigate environmental and health impacts.

HEALTH RISKS OF AIR POLLUTION FROM WHEAT CROP RESIDUE BURNING

Wheat crop residue burning poses significant health risks, primarily due to the release of harmful air pollutants such as fine particulate matter (PM2.5), carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOCs), and sulfur dioxide (SO2). These pollutants are emitted when wheat residues are burned after harvest, a practice common in states like Madhya Pradesh, Maharashtra, and Chhattisgarh.^[37,40] Among these pollutants, PM2.5 is particularly concerning as it can penetrate deep into the respiratory system, causing inflammation and exacerbating respiratory conditions like asthma, bronchitis, and chronic obstructive pulmonary disease (COPD).^[45-48]

VOCs play a significant role in worsening air pollution and human health, particularly in areas affected by crop residue burning. These compounds contribute to the formation of ground-level ozone and secondary particulate matter, both of which degrade air quality and pose serious health risks. Prolonged exposure to VOCs can lead to a range of respiratory issues, including asthma, bronchitis, COPD, and lung irritation. VOCs also contribute to cardiovascular problems by causing inflammation in blood vessels, increasing the risk of atherosclerosis and high blood pressure. Some VOCs, such as benzene, formaldehyde, and toluene, are known carcinogens, significantly raising the risk of lung cancer and other cancers over time. Furthermore, long-term exposure can lead to neurological effects, such as memory impairment, cognitive decline, and mood disorders, particularly affecting vulnerable groups like children and the elderly. In regions where crop residue burning is common, VOCs are released into the air, aggravating the overall pollution and worsening health outcomes, especially for individuals with pre-existing respiratory or heart conditions. The synergistic effect of VOCs with other pollutants, such as particulate matter and nitrogen oxides, increases the toxicity of the air, further heightening the health risks for those exposed.

Exposure to pollutants from crop residue burning, particularly fine particulate matter (PM₂.₅), has several detrimental effects on respiratory health. These particles can penetrate deep into the lungs, reaching the alveoli, where they trigger the release of cytokines and chemokines, activating immune cells and leading to chronic inflammation, an underlying factor in asthma, bronchitis, and COPD. Additionally, pollutants generate reactive oxygen species (ROS) that overwhelm the body’s antioxidant defence, resulting in oxidative stress and damage to airway epithelial cells, thereby impairing lung function and increasing susceptibility to infections. In children, long-term exposure to such pollutants can hinder lung development, reduce overall lung capacity, and elevate the risk of childhood asthma and lifelong respiratory complications. Furthermore, VOCs and particulate-bound allergens may sensitize the immune system, heightening the risk of allergic conditions such as allergic rhinitis and asthma.

Long-term exposure to these pollutants is also linked to cardiovascular diseases, such as heart attacks and strokes.^[4,49] Pollutants released during crop residue burning can adversely affect cardiovascular health through several interconnected mechanisms. When inhaled, fine particulate matter and gaseous pollutants can enter the bloodstream from the lungs, triggering low-grade systemic inflammation that damages blood vessels and contributes to atherosclerosis and vascular dysfunction. These pollutants also impair the function of endothelial cells lining the blood vessels, reducing nitric oxide availability, which leads to vasoconstriction and elevated blood pressure. Additionally, exposure can disrupt the autonomic nervous system, decreasing heart rate variability and increasing sympathetic nervous activity, thereby heightening the risk of arrhythmias and sudden cardiac events. Moreover, pollutants promote a pro-thrombotic state by increasing blood coagulability, which can result in the formation of clots, raising the likelihood of heart attacks and strokes. Vulnerable populations, including children, the elderly, and individuals with pre-existing health conditions, are particularly at risk from the health impacts of air pollution from crop residue burning.^[7] Short-term pollution spikes during the post-harvest season have been associated with a rise in hospital admissions and emergency visits for respiratory and cardiovascular ailments.^[50]

In November 2017, Delhi-NCR faced one of its most severe air pollution episodes, with Air Quality Index (AQI) levels soaring beyond 999 in several locations, far exceeding the “hazardous” threshold. This alarming spike was primarily attributed to large-scale crop residue burning in Punjab and Haryana, compounded by low wind speeds and persistent vehicular emissions that caused pollutants to remain trapped near the surface. The health impact was immediate and widespread: hospitals across the region reported a 30-40% increase in cases of respiratory distress, including asthma attacks, wheezing, eye irritation, and chronic coughing. The All India Institute of Medical Sciences (AIIMS) noted a sharp rise in pediatric respiratory admissions. A subsequent report in The Lancet linked this acute exposure to elevated hospitalizations for cardiopulmonary conditions. In response, authorities closed schools, restricted outdoor activities, and declared a public health emergency.

Similarly, a year-round study conducted in 2018 by the Indian Council of Medical Research (ICMR), in collaboration with the WHO and local hospitals, investigated the impact of air pollution on cardiovascular health in Kanpur, Uttar Pradesh, one of India’s most polluted cities. The study focused especially on the peak pollution months from October to January, when PM₂.₅ levels frequently exceeded 200 µg/m³. Prolonged exposure to such high concentrations of fine particulate matter was found to significantly elevate biomarkers associated with inflammation and blood coagulation. As a result, the study observed a 20-25% higher prevalence of hypertension and ischemic heart disease among the exposed population. Additionally, participants demonstrated reduced heart rate variability, a known early indicator of cardiac dysfunction. Many individuals also reported worsening of pre-existing cardiovascular conditions during the winter months, underscoring the serious health risks linked to seasonal air pollution spikes.

These case studies highlight the alarming health impacts of air pollution spikes, particularly in regions like Delhi and Kanpur, where high levels of particulate matter and other pollutants significantly affect public health. In both cases, exposure to elevated levels of air pollution led to a marked increase in respiratory and cardiovascular diseases, with vulnerable populations, such as children and individuals with pre-existing health conditions, suffering the most. The Delhi Smog Crisis of 2017 underscored the immediate health threats posed by crop residue burning and seasonal weather conditions, while the ICMR study in Kanpur demonstrated the long-term cardiovascular risks linked to chronic exposure to polluted air. These findings emphasize the urgent need for effective air quality management and public health interventions to mitigate the devastating health consequences of air pollution in India.

MITIGATING AIR POLLUTION AND HEALTH RISKS

Mitigating air pollution from wheat crop residue burning in central India requires a multi-pronged approach involving technological innovation, policy interventions, and farmer education. A promising solution is the adoption of zero-till farming and residue management technologies, such as the Happy Seeder, which enables farmers to sow crops without burning residues.^[43] These technologies not only reduce the need for residue burning but also improve soil health and crop yield. Promoting alternative residue management techniques like composting, mulching, and integrating residues into animal feed can further reduce the volume of burnable crop waste.^[51] Financial incentives, such as subsidies for machinery and equipment that aid in residue management, can encourage farmers to adopt sustainable practices.^[52,53] Public awareness campaigns that highlight the health risks and environmental impacts of burning, along with stronger enforcement of regulations, can also play a crucial role in reducing air pollution.^[54] Additionally, investments in research and development to provide region-specific solutions and improve the viability of alternatives will be essential. By combining these strategies, central India can adopt more sustainable agricultural practices that protect both air quality and public health. Table 1 presents a comparison of the feasibility and effectiveness of sustainable agricultural practices for crop residue management in India, focusing on small-scale versus large-scale farmers.

CONCLUSION

In conclusion, wheat crop residue burning in central India represents a critical challenge for both public health and environmental sustainability. The practice becoming widespread in major wheat-producing states like Madhya Pradesh, Maharashtra, and Chhattisgarh, significantly contributes to air pollution and exacerbates respiratory and cardiovascular health problems. The harmful pollutants released, particularly fine particulate matter (PM2.5), pose serious risks to vulnerable populations, including children, the elderly, and individuals with pre-existing conditions. While the practice of burning remains entrenched due to economic and logistical reasons, it is imperative that alternative residue management techniques, such as composting, mulching, and the use of technology like the Happy Seeder, are promoted and adopted. Ultimately, addressing the health risks of crop residue burning requires a holistic, long-term commitment to sustainable agricultural practices and public health interventions. By fostering an environment of education, technological innovation, and supportive policy, central India can mitigate the adverse effects of wheat crop residue burning and pave the way for a healthier, more sustainable future.