Smoke over South Asia: what burning waste and farm fields does to the air

Picture a rice harvest in northern India or Pakistan. The grain is in, the straw is left, and wheat has to go into the ground within weeks. A match clears the field in an afternoon. Multiply that by millions of fields, add the rubbish fires at the edges of towns, and you get the smoke that settles over South Asia.

The numbers behind the haze
IQAir's 2023 World Air Quality Report, as reported by Al Jazeera, put Bangladesh's average PM2.5 at 79.9 micrograms per cubic metre. That is nearly 16 times the WHO guideline of 5. Pakistan averaged 73.7 and India 54.4. Among cities, Begusarai in India averaged 118.9, Lahore 99.5, New Delhi 92.7 and Dhaka 80.2. The report found 83 Indian cities above ten times the WHO limit. San Juan, Puerto Rico, the cleanest city in the report, averaged 2.7.

The Air Quality Life Index from the University of Chicago's Energy Policy Institute, published in August 2023, estimates that PM2.5 cuts the average Indian's life expectancy by 5.3 years and a New Delhi resident's by 10 years. An Imperial College London review from April 2023, also cited by Al Jazeera, links air pollution to low birth weight, miscarriages and stillbirths.

You do not need a monitor to notice it. If you live in one of these cities, you smell the smoke before you read the number, and your children breathe it on the walk to school.

Fields on fire
Researchers at Harvard University and MIT studied crop residue burning in India and published their findings in Nature Communications in November 2022. They link the burning to between 44,000 and 98,000 premature deaths from PM2.5 every year. Punjab, Haryana and Uttar Pradesh account for 67 to 90 percent of those deaths.

Six districts in Punjab stand out. According to the authors, they account for 40 percent of India's population exposure to fire-related PM2.5 and about 27,000 premature deaths. Coarse rice varieties leave more residue per unit of crop, and the districts sit largely upwind of densely populated areas. The study also found that 88 to 95 percent of the impact from Indian burning falls inside India. Smoke from Indian burning does reach Bangladesh, Nepal and Pakistan, though those countries see only 0.24 to 12 percent of the exposure that India sees.

The authors offer two ways to reduce the harm. Burning two hours earlier in the day could avert up to 14 percent of the impact, or about 10,000 deaths a year in Punjab. Growing varieties such as basmati, which leave less residue, could cut it further.

Why the fires keep burning
Al Jazeera reports that Punjab in Pakistan has banned crop burning, yet farmers keep doing it illegally, possibly because the alternatives cost too much. A ban removes the match but leaves the straw. A farmer with a short window between harvests still needs somewhere for the straw to go, and a town with a pile of rubbish needs the same.

Rubbish fires add to the load
Fields are one source. The IQAir report also names plastic rubbish incineration as a contributor to worsening air quality in Bangladesh.

The WHO puts the global toll in context. Its 2018 release estimated that ambient air pollution alone caused some 4.2 million deaths in 2016, and that cooking with polluting fuels and technologies caused about 3.8 million more. WHO also estimated that around 90 percent of the world's population breathes polluted air.

Where Nexus Biofuel fits
Nexus Biofuel Inc., based in Kelowna, BC, converts waste streams, including biomass and municipal solid waste, into usable energy. Crop residue is biomass, and household rubbish is municipal solid waste. Both are waste streams the company's process is built to handle, and its equipment avoids incineration, so it does not replace one open fire with another.

The equipment is portable and economical. A farmer, a town or a city that cannot afford a large fixed plant can bring the equipment to the waste instead of hauling the waste to a plant.

Burning is cheap and fast, and the people who breathe the smoke pay for it later. Nexus Biofuel aims to cut fossil fuel reliance and greenhouse gas emissions, and to create jobs, by treating straw and rubbish as energy sources. That gives a farmer or a town a reason to keep waste out of the fire, and it gives a city a way to clear the air without waiting for the next harvest to end.