Chandigarh: Despite a significant decline in stubble-burning incidents in Punjab and Haryana this year, Delhi’s air quality remains hazardous, spotlighting local sources as key contributors to the toxic haze over the national capital. With farm fires down by 74% in Punjab and over 44% in Haryana compared to previous years, experts and officials are questioning whether stubble burning is truly the primary culprit behind Delhi’s persistent air pollution issues.
As Delhi’s residents continue to face severe pollution, allegations against farmers in neighbouring states persist. Every year, from October to November, farmers burn crop stubble left over from paddy harvesting to prepare fields for wheat. Critics argue that the smoke from these fires releases high levels of particulate matter (PM2.5), carbon monoxide, and other pollutants into the atmosphere, exacerbating air quality problems in Delhi and the National Capital Region (NCR). Yet, some experts contend that stubble burning is only a part of the equation, with local sources accounting for the majority of the pollution.
Farm fires in Punjab have drastically reduced from 22,981 incidents between 15 September and 8 November in 2022 to 6,029 incidents during the same period this year. Haryana reported only 906 cases, down from 1,605 last year.
Despite this decline, Delhi’s air quality has continued to degrade, with no days recorded in the “good” category. Local sources, including vehicular and industrial emissions, seem to be filling the gap left by the reduction in stubble burning.
A recent research report by the Centre for Science and Environment (CSE) underscores the role of local pollution sources, with vehicular emissions emerging as the primary contributor. The emission inventory studies for Delhi, including those conducted by IIT Kanpur in 2015 and TERI-ARAI in 2018, suggest that the transport sector alone contributes between 20% and 41% of PM2.5 levels in the city. Delhi has a burgeoning vehicular population, with the Economic Survey of 2023-24 reporting a stock of 7.9 million vehicles in the city, including 6.5 lakh new vehicles registered in the past year alone. Nearly 90.5% of these vehicles are two-wheelers and private cars.
An explosive rate of motorization further exacerbates the situation. The city sees around 1,100 new two-wheelers and 500 private cars registered daily. Experts argue that this growth rate, alongside inadequate public transport services and congestion, offsets any gains from emission control measures.
“Despite efforts to curb vehicular pollution, explosive motorization and inadequate public transport options continue to thwart emission reduction efforts,” CSE’s report notes. Initiatives like the CNG program for public transport, the phasing out of old diesel and petrol vehicles, restrictions on non-destined trucks, and the adoption of Bharat Stage 6 emission standards have yet to yield substantial results due to the growing mobility crisis in Delhi.
This year, the average contribution of stubble burning to Delhi’s PM2.5 levels from 10-20 October was only 0.7%, indicating a minimal impact. However, farm fire impact surged later, with stubble burning contributing around 16% to PM2.5 levels on 23 October, when the concentration reached 213 µg/m³—classified as “very poor.” Despite fluctuating contributions from stubble burning, PM2.5 concentrations remained high, peaking at 206 µg/m³ on 31 October, suggesting that other sources sustained the pollution levels.
According to recent data from the Indian Institute of Tropical Meteorology (IITM) in Pune, stubble burning contributed only 1.3% of air pollution in Delhi on 19 October. IITM projections estimate a slight increase, predicting a contribution of around 2.3% and 2.4% on October 20 and 21, respectively.
But claims by the System of Air Quality and Weather Forecasting and Research (SAFAR) are contrary. SAFAR has noted that during peak burning periods, stubble burning can contribute up to 40% of Delhi’s PM2.5 levels. On 1 November, the daily contribution of stubble burning reached a high of 35.2%, according to the Centre’s Decision Support System. The variability in these figures, influenced by wind direction and atmospheric conditions, reflects the complexity of accurately attributing pollution solely to stubble burning.
Many experts argue that Delhi’s pollution problem is largely home-grown. Dr Virender Singh Lather, former Principal Scientist at ICAR-IARI New Delhi, stated, “Nearly 90% of Delhi’s air pollution is due to local sources. Even if farmers stopped growing paddy, Delhi would still face severe air quality issues.” Dr Lather explained that stubble burning occurs when wind speeds are below 5 km/h, causing heavier PM2.5 particles to remain localized within a radius of 10-15 kilometers. “Technically, pollution from stubble burning occurring hundreds of kilometres away cannot significantly impact Delhi’s air quality.”
Further challenging the blame on stubble burning, Justice Sudhir Aggarwal, a member of the National Green Tribunal (NGT), expressed scepticism, noting that there is no scientific evidence conclusively linking stubble burning in Punjab and Haryana to Delhi’s pollution crisis.
In an unusual turn, Punjab farmers were also accused of contributing to cross-border pollution this year. Marriyum Aurangzeb, Pakistan’s Senior Minister for Environment and Climate Change in the Punjab government, claimed that “eastern corridor winds from India” were bringing pollution to Lahore, escalating the city’s smog levels. This accusation highlights the regional dimensions of the pollution issue and raises questions about shared environmental accountability.
Alongside vehicular emissions, other sources of pollution are increasingly scrutinized. Aircraft operations at the Indira Gandhi International Airport (IGI) in Delhi are also significant contributors. Handling around 1,500 flights daily, each aircraft emits substantial quantities of CO2. Aviation, while only accounting for approximately 2.4% of global CO2 emissions, contributes disproportionately to urban pollution due to its high CO2 output per hour compared to other modes of transport.
Industry emissions, construction dust, and waste burning also add to Delhi’s air quality woes, further diminishing the impact of any reduction in stubble burning.
While farmers in Punjab and Haryana are often vilified for stubble burning, experts recognize the challenge they face. Many farmers, especially the small farmers with land holding below four acres, lack affordable alternatives for disposing of crop residue, and burning remains the quickest and least costly option to clear fields before the next planting season. Attempts to introduce in-situ management practices, such as using bio-decomposers, are underway but have yet to achieve widespread adoption due to high costs and logistical challenges.
“Farmers do not want to burn crop waste. But the machines are beyond the reach of small farmers, around 40% farmers do not even have a tractor, how they will manage the crop waste”, said a farmer leader Ratan Mann.
While stubble burning undoubtedly contributes to Delhi’s air pollution, experts assert that it is far from the only factor. Focusing on a holistic approach that includes curbing vehicular emissions, enhancing public transport, controlling industrial pollution, and implementing affordable alternatives for farmers could provide more effective relief.