Open burning main cause of air pollution

Kathmandu, Mar. 21: Air pollution remains a significant environmental challenge in several urban areas of the country, particularly in the Kathmandu Valley. The country consistently ranks among the top 10 most polluted cities in the world, posing serious risks to public health and the environment.

A ‘World Air Quality Report 2024,’ published by Switzerland-based organisation IQAir published this week also showed that Nepal ranked seventh among the most polluted countries in the world.

As per the report, Kathmandu has become the eighth most polluted city in the world. The report was prepared based on the concentration of delicate particulate matter known as PM2.5 in the air. The report also said that in 2024, Nepal's annual average PM2.5 concentration was 42.8 micrograms per cubic metre, while in the capital city, Kathmandu, it was 45.1 micrograms per cubic metre.

Forest fires are a major contributor to air pollution in the country during the dry season (March to April), particularly in the Kathmandu Valley. With the onset of the pre-monsoon season, forest fire incidents have been on the rise. In the past week alone, 100 forest fire incidents have been reported across the country, according to Disaster Portal.

A recent study indicated that wildfires in the country threaten nearly 500 million tonnes of carbon storage and pose a significant risk to biodiversity. The study also warned that the wildfire season has just begun, and the worst is yet to come.

The study published in the Information Geography journal highlights that Nepal’s forests face serious threats from climate-exacerbated wildfires. 

The research, conducted by an international team of scientists, estimated that if fire risks remain unchecked, 170 million tonnes of soil carbon and 325 million tonnes of wood carbon could be released into the atmosphere, further worsening global climate challenges. According to the study, Nepal’s southern provinces Lumbini, Madhes and Sudurpaschim are at highest wildfire risk. Six of Nepal’s 20 protected areas, including Chitwan and Bardia National Park, are under extreme threat, endangering rare species like Bengal tigers, one-horned rhinos and wild elephants. Additionally, air quality in main cities including Kathmandu could deteriorate further due to increased wildfires, the research said.

Peril of forest fires

According to recent data, wildfires are currently burning in 436 locations across 53 districts. The risk is expected to peak in April and May. “Like the Los Angeles wildfire, Nepal is trapped in a carbon-temperature feedback loop,” said Kshitij Dahal, a doctoral student at Arizona State University, USA and lead author of ‘Nepal's carbon stock and biodiversity are under threat from climate exacerbated forest fires.’

Air quality specialist Dr. Bhupendra Das explained that air pollution can be categorised into three types -- open burning, technology-based emissions, and fugitive emissions. While the latter two are common year-round, open burning -- including forest fires, crop residue burning, and trash burning -- occurs seasonally.

Dr. Das highlighted that biomass burning accounts for nearly 80 per cent of air pollutants released between February and June. 

Open burning of biomass is a significant contributor to air pollution in Nepal.

April marks the peak period for biomass burning, whereas July and August, being the monsoon season, record the lowest number of active biomass fires. Citing Earth Data from 2022, Dr. Das noted that a total of 300,721 biomass fire spots were detected in Nepal between 2012 and 2021 using VIIRS-375m resolution satellite data.

“This is the season for forest fires and crop residue burning. Such open burning releases black carbon, which poses serious risks to human health and is a major contributor to global warming,” Dr. Das said. Apart from GHGs, open burning sources release tremendous amounts of short-term pollutants, especially black carbon (BC) which has a high potential for regional/local warming, he added.

“There is a way to minimise the risk, but it requires coordinated efforts from all three levels of government to control the seasonal release of polluting black smoke. Strong policies and their effective implementation are crucial to curbing seasonal open burning. Also, creating artificial recharge ponds within forests can help extinguish fires more quickly and aid in recharging the land, reducing the risk of wildfires spreading further,” Dr. Das suggested.

Pashupati Nath Koirala, Director of StoryCycle, Climate and Forest, warned, “Forest fires are most dense in isolated forest areas and along main roads. Many occur in protected areas due to both effective and ineffective management. These fires not only threaten biodiversity but also undermine Nepal’s carbon trade benefits and its goal of becoming a net-zero carbon country by 2045.”

Emissions from petrol- and diesel-run vehicles are another major year-round source of pollution in the Kathmandu Valley. In March 2018, the Nepal government introduced a nationwide ban on public vehicles older than 20 years; however, the ban has not been effectively enforced.

Local level initiation

To control air pollution in Kathmandu, the Kathmandu Metropolitan City, in coordination with the Traffic Police, has been inspecting such polluting vehicles to help curb air pollution.

Sarita Rai, Chief of the Environment Department at the Kathmandu Metropolitan City (KMC), said they have been monitoring vehicles at various locations within the city and imposing fines on those emitting black smoke.

“We have started detaining such vehicles and issuing fines daily. So far, we have inspected 13,000 vehicles and imposed a fine of Rs. 1,000 per violation,” she said. “We are facing challenges in holding these vehicles due to limited space, but we continue to monitor and take action every day,” she added.