Stubble burning in India affecting other south Asian countries too; but most of the impact is within India, say US researchers
Interventions to reduce stubble burning and the pollution it causes need to be focussed on just six districts of Punjab — Barnala, Sangrur, Patiala, Moga, Ludhiana and Fatehgarh Sahib — a new research by scientists from Harvard University and the Massachusetts Institute of Technology (MIT) in the United States has advised.
These six districts should be focussed upon as they contribute 40 per cent of India-wide exposure to fire-related PM2.5, according to the research published November 14, 2022 in the journal Nature Communications.
The scientists studied and analysed the burning events, locations and times that produced the greatest increases in population exposure, premature deaths, and economic losses in India during 2003-09.
“Then they quantified how small-scale and targeted actions could reduce air pollution and health risks for the entire population,” an article on MIT’s website said.
The researchers attributed between 44,000 and 98,000 PM2.5-exposure-related premature deaths annually to crop residue burning.
Some 67-90 per cent of these occurred as a result of burning that took place in Punjab, Haryana, and Uttar Pradesh, the MIT website article said.
“Our study shows that a small number of administrative areas may be prioritised for interventions to effectively reduce the attributable impacts from fires, with burning in six districts in Punjab responsible for 40 per cent of India-wide exposure to fire related PM2.5,” the authors of the study noted.
The six districts, all of which are situated in the Malwa region that lies between the Sutlej and Ghaggar rivers, grow coarse varieties of rice that generate more residue to be burned for the same amount of crop production.
“They are mostly upwind of densely populated regions. As a result, they are on average responsible for 40 per cent (27,000 deaths, valued at $9.0 billion) of the total air quality impacts in India due to burning, with Patiala and Sangrur alone contributing 20 per cent,” the research said.
The scientists also suggested what these interventions should be. They said if farmers in Punjab were to burn crop residues two hours earlier in the day, they could avert up to 14 per cent of air-quality impacts and about 10,000 deaths each year.
Farmers could achieve further reductions by adopting rice varieties such as basmati that require less residue burning.
“Finally, such targeted actions could achieve most of their benefits if adopted in just a few regions, given the large contribution from the aforementioned six districts in Punjab,” the researchers said.
The study, titled Air quality impacts of crop residue burning in India and mitigation alternatives, also noted that stubble burning was having a detrimental impact on other countries with which India shares the Indo-Gangetic Plain (IGP):
The IGP is home to millions of people residing in not only northern India but also Nepal, Bangladesh and Pakistan. Agricultural fires in India are not subject to political borders and may have air quality impacts on neighboring countries as well.
The researchers used data from 23 years of forward simulations to find that PM2.5 exposure in Bangladesh, Nepal and Pakistan resulting from Indian crop residue burning was 0.24-12 per cent of that in India.
They added that impacts were lower in Bangladesh and Nepal (1.3-2.2 per cent), whereas Pakistan’s PM2.5 enhancement averaged 6.9 per cent of that in India.
“We show that over 23 years, annual mean total increase in population exposure due to Indian crop residue burning is 4.5 ×109×109 people∙μ∙μg m−3 in India, 2.6 ×108×108 people∙μ∙μg m−3 in Pakistan, 7.8 ×107×107 people∙μ∙μg m−3 in Bangladesh and 4.2 ×107×107 people∙μ∙μg m−3 in Nepal,” the scientists noted.
This means that the majority (88-95 per cent) of burning-related population exposure is experienced by the Indian population as large-scale meteorological winds carry pollution into, rather than away from, India as well as the high population density.
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