Cleaning up the Himalayan airshed

When I landed in Kathmandu last November, I arrived with a Diwali hangover. Not the festive kind, but the coughing, dust-coated, throat-scratching kind gifted by North India’s winter air. After a decade of breathing in Delhi’s seasonal gas chamber, my lungs were in an open revolt. But within days of landing in Kathmandu, my cough vanished. It felt almost miraculous. The air was crisper. The Air Quality Index was kinder, and the Himalayan peaks rose on the horizon. 

But by the third week, the familiar grey veil returned. First as a faint blur, then peak by peak the Himalaya began to disappear. Locals said it had been getting worse every year. 

Much of this haze is not Kathmandu’s doing. What drifts into Nepal each winter is a toxic spillover from the plains of North India and Pakistan: black carbon, brown clouds, and fine particulate matter carried across borders by seasonal winds. Kathmandu’s bowl-shaped valley simply traps what the region exhales.

Abid Omar, founder of the Pakistan Air Quality Initiative, put it bluntly: “We often view air pollution and climate change as separate silos, but in the Himalaya, they are one and the same.”

Black carbon is essentially soot from diesel emissions, brick kilns, and crop burning. It may be short-lived in the atmosphere, but when ash settles on snow and ice, it reduces reflectivity and accelerates melting. 

Omar adds, “Black carbon is a threat to the water security of the entire Indus and Ganges basins.”

What burns on both sides of Punjab do not stay in Punjab. It ends up on glaciers that feed rivers, sustaining hundreds of millions of people downstream.

In November 2024, AQI levels in New Delhi hovered near 500 and about the same time Lahore briefly became the world’s most polluted city, with the AQI count crossing 1,100. These numbers are not abstract.

According to the State of Global Air 2024 report, India recorded more than 2 million deaths attributable to air pollution in 2023. Bangladesh and Pakistan each saw over 200,000 deaths. Air pollution is now one of the leading causes of premature death across South Asia.

Nepal, often imagined as cleaner by default, tells a sobering story of its own. Air pollution in Nepal led to an estimated 48,500 premature deaths, with the loss of more than 1.4 million disability-adjusted life years. The University of Chicago’s Air Quality Life Index estimates that particulate pollution cuts 3.4 years off the life of the average Nepali. In the Tarai region, life expectancy drops by nearly five years. In Kathmandu, residents lose 2.6 years.

Says infectious disease specialist Anup Subedee: “Air pollution is killing at a far higher rate than Covid-19 did during its worst years in Nepal. People are dying in their twenties of cancer, or having heart attacks and strokes in their thirties and forties.”

Nearly 40 per cent of winter particulate pollution in the Kathmandu valley originates outside Nepal. Black carbon carried from Punjab, Haryana, and Uttar Pradesh in India, besides parts of Pakistan, rides the winds north, settles on Himalayan snow, and accelerates glacier melt by absorbing heat.

“The pollutants travel across borders within shared airsheds, creating one gigantic plume of polluted air over India, Nepal, Bangladesh, and Pakistan several times a year,” says Subedee.

In some Himalayan regions, scientists estimate that black carbon can increase localised melt rates by up to 30%. Yet global climate negotiations continue to treat glacial loss primarily as a carbon dioxide problem. 

CHINA’S APPROACH

The South Asian story is transboundary, and more immediate as well as more preventable. This is not only about emissions. It is about coordination, and China offers an instructive contrast.

Since 2013, China has dramatically improved its air quality by declaring a 'war on pollution'. A major air pollutant, suspended PM2.5 levels fell sharply through strict controls on coal, vehicles, and industry, massive investment in renewables, and legally binding national action plans.

Crucially, China shifted from city-by-city firefighting to a regional airshed approach. Provinces shared data, coordinated emergency responses, enforced unified standards, and tied environmental performance to political accountability. South Asian countries have done none of this.

Isolated national actions are insufficient when pollution itself ignores borders. India, Nepal, Bangladesh, and Pakistan share the same airshed. Without cooperation, each country keeps breathing its neighbour’s mistakes.

“As the government representing the largest population affected by air pollution, India should lead this effort. Instead, the region has drifted away from cooperation, and the cost is becoming catastrophic,” Subedee says.

The haze over Kathmandu is not only Nepal’s burden. It is a regional failure. The melting of South Asia’s glaciers is not just a global warming story. It is also a local one, written in the smoke rising from our own fields, factories, and highways.

If we keep ignoring black carbon, the Himalayas will keep losing time, snow, and stability. The disappearing peaks of Kathmandu are not a metaphor. They are a warning.

And like the air itself, that warning is already crossing borders. ©Sapan News

Pragyan Srivastava is an Indian journalist and associate editor at Sapan News. pragyan@sapannews.com