A large amount of rice straw is burned after the kharif crop season in the northwest India region. This practice of crop residue burning releases large amounts of pollutants into the atmosphere, causing severe conditions for human health and economic activities. The Aakash project is delineating the science of air pollution in the region (including the national capital of Delhi), raising social awareness, and exploring ways for sustainable agriculture.

In the Punjab and Haryana region of northern India (Figure 1), double cropping of rice and wheat is popular since the green revolution. However, to alleviate deepening groundwater level, rice planting is delayed until the beginning of the rainy season by the Preservation of Subsoil Water Act (2000). This has shortened the gap for field preparation between rice harvesting and wheat seeding. The delayed rice straw burning, during mid-October to mid-November, causes the smoke to reside longer in the atmosphere and is believed to affect air pollution in neighboring areas, including the national capital region (NCR) of Delhi. (Photo 1)

The National Green Tribunal Act (2010) passed an order in2015 to ban agricultural residue burning in Northwestern Indian states (Punjab, Haryana, Delhi-NCR and Rajasthan). For such policies to be effective, it is important that the people of this region become more aware of the health hazards caused by air pollution and motivate themselves to improve the environment in the surrounding through their own efforts. We, at the Aakash Project, are involved in related research activities by following three working groups:

The Air Pollution Group estimates the amount of air pollutants emitted from straw burning and compares the simulation results with observed values to clarify the relationship between straw burning and local-regional air pollution. Conducting intensive observation of air pollutants over a wide area during the straw burning season, the team will compare and verify the simulation results with PM_2.5 and related air pollutant observations. By presenting the best scientific knowledge, we aim to make residents aware of the effects of straw burning.

The Health Group aims to raise awareness of the importance of maintaining clean air among residents by holding health classes and conducting health checkups. Results from the air pollution group provide more accurate information on human exposure by mapping observation based PM_2.5 concentrations at surface level, which has been lacking in the source region (Figure 2). We also provide quantitative assessment of crop residue burning contribution to PM_2.5.

The Rural Village Group is working to propose effective ways to use rice straw, through in situ or ex situ management methods. With the cooperation of local universities and research institutes, we are considering ways to use rice straw while respecting the cultural and socio-economical background of the region. We are also conducting field experiments on the university campus on crop diversification toward deriving co-benefit for air pollution and greenhouse gases emission mitigation.

We hope our activities will help the local people regain clean air.

What we know so far

We have conducted surveys in Punjab. Two of them asked village representatives how they manage rice straw in their respective villages and the area of paddy fields where straw burning was done. Apart from that, two questionnaire-based interview surveys were conducted with both 2,200 households in all districts and all farmers’ households in one village of Punjab. As a result, most farmers responded that air pollution is a problem, but that the main source of air pollution in Delhi is not straw burning in the Punjab, but sources of pollution around Delhi. The areas of higher and lower fraction of rice stubble burning, as assessed from the surveys, are well supported by remote sensing measurements of fire detection counts, which are indicative of crop residue burning.

To elucidate the link between rice crop residue burning and Delhi’s air pollution, we conducted intensive observations of air pollution in Punjab, Haryana and Delhi-NCR in the fall of 2022 and 2023. We observed the pollution “events” in Delhi-NCR due to transport of emissions from straw burning in the source region of Punjab during early November of both years (RIHN press release, research news). Further research is being conducted to estimate the contribution of crop residue burning to harmful air pollutants and identify causes of the decrease of PM2.5 in rural areas and an increase in Delhi-NCR in 2023, relative to 2022 (Figure 2). Preliminary analysis suggests a decrease of fire detection counts from satellite over Punjab and Haryana, while a more stagnant condition prevailed over Delhi-NCR in 2023 in comparison with those in 2022.

Noteworthy items

We are making considerable progress in understanding the cause of high PM_2.5 air pollution events in Punjab, Haryana and Delhi-NCR using the low-cost sensor (CUPI-G) deployment at about 30 sites. Based on our analysis of 2022 measurements, made in the first half of 2023 (Singh et al., Sci. Rep., 2023), we provided operational update of PM_2.5 and other meteorological conditions over the northwest India region on regular basis. A tracer simulation model was also set up to predict the pollution transport from the crop residue burning regions (as seen by fire detection counts) for the next couple of days. Details on the updates from 2023 field campaign can be seen at: https://aakash-rihn.org/en/data-set/   

Interviews with stakeholders such as farmers, cooperative societies are carried out to the point of views on two promising options for stopping straw burning: (1) shift from rice to other crops and (2) promote use of rice straw as biomass fuel.  options. We are currently working with Japanese companies, and Japanese and Indian government and non-government organizations to continue to find ways to help the modern technology take root locally.

Annual Report