A Burning Issue: Managing Air Quality in Cities and Rural Areas

Despite its harmful effects, the practice of burning leftover crops in fields remains common across Asia. Photo: ADB
Despite its harmful effects, the practice of burning leftover crops in fields remains common across Asia. Photo: ADB

By Yoko Watanabe, Yasmin Siddiqi

There are viable solutions for the harmful practice of agricultural burning but they need government and private sector support to scale up.

Air pollution is one of the most critical environmental and health problems globally. It is particularly acute in industrializing countries, cutting across geographical boundaries and seemingly unrelated sectors. 

As populations continue to grow in cities and as urban areas expand, demand for food production in rural areas is increasing, which in turn is serving as an important source of livelihood for the rural workforce. However,  this positive relationship between city and countryside is turning negative because of the practice of burning leftover crops in the fields.

Burning crop residue speeds up the process of preparing fields for new crops, which helps with the growing demand for food. This solidifies the food supply chain and keeps rural incomes flowing but it also causes great harm. It generates air pollution which affects human health and ironically also reduces crop productivity due to reduced soil fertility by up to 30%. Burning leftover crops also emits greenhouse gases, exacerbating climate change. 

The practice is the main culprit behind the toxic haze experienced in Bangkok, Delhi, Lahore, and many other Asian cities. For example, in November 2023 crop residue burning in the nearby states of Haryana and Punjab drove up the pollution levels in Delhi to the equivalent of smoking about three cigarettes per day.

 Despite the negative impacts, burning leftover crops in the field is widely practiced in Asia. In India alone, about 683 million tons of crop residue is generated annually of which about 20% (140 million tons) are burned. 

Between 2003 to 2019, agricultural residue burning is estimated to have caused 44,000–98,000 premature deaths due to particulate matter exposure in India annually. In March 2023, over 1.3 million people in Thailand were reported as being adversely affected by air pollution, with at least 200,000 being hospitalized in a single week. Much of the haze was due to agricultural burning.

While there are various solutions to avoid burning, each comes with a cost - such as transportation costs for off-site disposal of the residue, and costs for mechanically ploughing post-harvest stubble back into farm soil. Hence, the harmful practice of burning is currently recognized as the cheapest and easiest option for farmers. 

There are a wide range of options to burning. Crop residue can be used to make organic fertilizers for mushroom growing, for making biogas, and as a low carbon fuel in industries, and for electricity generation. 

All these solutions have been proven to work but they are being applied in small pilot programs. They need urgent scaling up and replication. 

Despite the negative impacts, burning leftover crops in the field is widely practiced in Asia.

Governments and their partners must raise awareness and disseminate best practices among farmers across vast regions, encouraging them to view crop residue not as a problem, but as a valuable resource for generating additional income.

One innovative approach in India found that using biochar, a type of charcoal made from burning plant materials, as a fertilizer can increase crop yields by about 27% more than using chemical fertilizers. This method can also increase farmers' income by up to 50%. 

A pilot project in Shandong Province in the People’s Republic of China resulted in a reduction of 1,579 tons of carbon dioxide emissions per year by sustainably reusing 1000 tons of wheat and maize straw. It also resulted in additional income of $539 per hectare for farmers reusing the straw. Such information could be widely shared with farmers by government agencies, civil society groups, and academia.

Though successful, the pilot projects show that each solution involves collaboration among multiple actors, and each of them has a critical role to play. Government has an extremely important role in creating an enabling environment through policies and incentives to make each step of the supply chain viable. The private sector and civil society could innovate the technologies and raise awareness and interest. 

For example, converting the paddy straw into biogas requires public and private investors to set up biogas processing plants and a paddy straw collection system involving hundreds or thousands of farms spread across large areas. The biogas produced then needs to be distributed by local government or private company to users for cooking and heating in homes or processed further for fuels in vehicles.  

Countries and companies are working hard to reduce carbon emissions.  New finance platforms are being established to provide incentives to farmers not to burn crop waste. There is also a growing interest in making biogas from farm waste. All these efforts could help to stop the practice of burning leftover crops in fields.

It is high time we realize that by stopping the practice of crop residue burning we can decrease hospital visits, save lives, and extend people's lifespans, while helping to address climate change.