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Another winter of discontent as Kathmandu braces for deadly air pollution

Air pollution in Kathmandu.

The effects of the air pollution in Kathmandu are compounded by the valley’s bowl-like topography, where the air stagnates for up to 18 hours a day, keeping the pollutant particles suspended in and over the city. Image by Kasia Trapszo via Flickr (CC BY-NC-SA 2.0).

  • As winter sets in, residents of Kathmandu are bracing for worsening air pollution levels that can exceed by a hundredfold the safe limit prescribed by the WHO.
  • The sources of the pollution are both local — vehicle exhaust fumes and burning of garbage — and from further afield, including firecracker residue from festivities in neighboring India.
  • A recent study says these combine to give Nepal the highest death rate from chronic lung disease of any country — a problem that experts say the government has repeatedly failed to recognize.

KATHMANDU — From early to mid-October, as Nepali Hindus celebrated the festivals of Dashain and Tihar, the skies over the Kathmandu Valley stayed a clear blue. To the north lay a panoramic view of the snow-capped Himalayas gleaming in the distance.

By the time the festivities were over, however, in late October, the city was enveloped in a blanket of haze; even the not-so-distant foothills of the Himalayas were hard to make out.

But the view, or the lack of it, is the least of the concerns for residents of Kathmandu, who every winter have to live through lung-wracking levels of air pollution. According to a recently published study that looked at data from 1990-2019, Nepal has the world’s highest death rate from chronic lung disease, at 182.5 per 100,000 population when adjusted for age.

“A host of factors create a situation in which the city’s air quality deteriorates rapidly,” said Bhupendra Das, the Kathmandu national technical expert at Clean Air Asia, an international NGO, who was not involved in the study.

Pollution over Kathmandu as seen from an aircraft in Oct. 2016, with the snow-capped Himalayas in the distance. Image by Phil Venditti via Flickr (CC BY 2.0).

The study authors, from universities in Iran, Australia, Cyprus, the U.K. and Canada, attributed the high burden of chronic obstructive pulmonary disease (COPD) to burning and vehicle exhaust fumes. “Although Nepal generates much of its electricity from clean hydroelectric sources, it suffers from high levels of air pollution from the burning of garbage and biomass and from road traffic,” the study says.

The effects of the air pollution are compounded by the Kathmandu Valley’s bowl-like topography, where the air stagnates for up to 18 hours a day, keeping the pollutant particles suspended in and over the city.

“There are various sources of air pollution in the Kathmandu Valley,” Das said. “Vehicular emission, garbage and agricultural waste burning, brick kilns and construction sites all contribute to air pollution.”

For much of the year, up until the festive season in October, monsoon winds blowing from the Bay of Bengal in the east bring 60-90% of Nepal’s annual rainfall, especially for the central and eastern parts of the country. The rains help flush the pollutants out of the air, which allows for clear skies during this period. But as winter starts setting in around the end of October, the easterly winds tail off, and the westerlies, originating from the Mediterranean, pick up. Although these bring some rainfall, mostly in western and central Nepal, they don’t carry as much moisture as the easterlies.

As a result, when the winter peaks in December and January, air pollution crosses hazardous limits in Kathmandu, reaching up to 100 times in excess of what the World Health Organization considers the safe daily limit for exposure to PM2.5 — a class of airborne pollutants so fine that they can be inhaled and cause respiratory disease.

In addition to particulate matter, high levels of polycyclic aromatic hydrocarbons, a class of chemicals found in coal, crude oil and gasoline, and associated with reduced lung function, exacerbation of asthma, and increased rates of COPD and cardiovascular disease, have also been recorded in Kathmandu.

Particulate matter forecasts in southern Asia. Image courtesy of Copernicus Atmosphere Monitoring Service.

The issue of air pollution has been raised since the late 1990s, but the government has failed to roll out policies and programs to tackle the problem, Das said.

“Although there is growing concern for air pollution, political leaders think it is part of a natural process and doesn’t matter much,” he said. “Also, usually [it’s] people with long-term terminal disease [who] are dying due to air pollution and that hasn’t caught the attention of policymakers.”

And when the rainy season rolls around again, he added, everyone just seems to forget the city’s pollution woes.

Another recent study, looking at the impact of air pollution on economically disadvantaged groups in various cities in the Hindu Kush Himalayan region, found that the urban poor are often exposed to higher-than-average levels of air pollution. Many of those affected say they believe air pollution poses a risk to their health and livelihoods, and are aware of the various consequences. But because of the nature of their livelihoods and their irregular incomes, they can’t reduce their overall exposure to air pollution, the study says.

In addition to local sources, pollutants are also carried by the winds blowing from the west. These include particulate matter from large-scale vehicle emissions, stubble burning and firecrackers, which are set off in massive numbers during the Deepavali festival, also in October, in the Indian states of Punjab and Haryana.

As a result, the whole of the Indo-Gangetic Plain, the fertile crescent that sprawls across much of Pakistan, northern India, southern Nepal and most of Bangladesh, is shrouded in a blanket of smog every winter.

Haze over the Indo-Gangetic Plain in Dec. 2011. The whole of the plain, the fertile crescent that sprawls across much of Pakistan, northern India, southern Nepal and most of Bangladesh, is shrouded in a blanket of smog every winter. Image by NASA.

But before the Nepali government can take up the issue with its neighbors, it first needs to address its own sources of pollution, Das said.

“When we are able to control our sources of pollution, only then can we raise the issue in regional forums,” he said. “But that doesn’t seem to be the case as political parties that are preparing to contest elections in Nepal in November haven’t prioritized this agenda.”

As temperatures drop, Nepalis, especially in Kathmandu, are bracing for another winter of potentially deadly air quality. Forecasts from various international agencies already show a rapid increment in pollutants over most of Nepal in the days to come.

Banner image: The effects of the air pollution in Kathmandu are compounded by the valley’s bowl-like topography, where the air stagnates for up to 18 hours a day, keeping the pollutant particles suspended in and over the city. Image by Kasia Trapszo via Flickr (CC BY-NC-SA 2.0).

Citations:

Safiri, S., Carson-Chahhoud, K., Noori, M., Nejadghaderi, S. A., Sullman, M. J., Ahmadian Heris, J., . . . Kaufman, J. S. (2022). Burden of chronic obstructive pulmonary disease and its attributable risk factors in 204 countries and territories, 1990-2019: Results from the global burden of disease study 2019. BMJ, 378. doi:10.1136/bmj-2021-069679

Chen, P., Kang, S., Li, C., Rupakheti, M., Yan, F., Li, Q., . . . Sillanpää, M. (2015). Characteristics and sources of polycyclic aromatic hydrocarbons in atmospheric aerosols in the Kathmandu Valley, Nepal. Science of The Total Environment, 538, 86-92. doi:10.1016/j.scitotenv.2015.08.006

Maharjan, A., Adhikari, S., Ahmad, R., Ahmad, U., Ali, Z., Bajracharya, S., . . . Singh, C. (2022). Air pollution exposure and its impacts on everyday life and livelihoods of vulnerable urban populations in South Asia. Environmental Research Communications, 4(7), 071002. doi:10.1088/2515-7620/ac77e0