KATHMANDU, Aug 28: A new study has revealed that Nepalis could gain an average of 3.3 years in life expectancy if air pollution were reduced to levels recommended by the World Health Organization (WHO).
The finding comes from the Air Quality Life Index 2025, released Thursday by the Energy Policy Institute at the University of Chicago. The report identifies polluted air as the biggest external threat to life expectancy in Nepal, measured against the fine particulate matter (PM2.5) standard.
In 2023, Nepal’s average PM2.5 concentration stood at 38.3 micrograms per cubic metre—10 percent higher than in 2022 and 7.6 times above the WHO’s annual safe limit of 5 micrograms. PM2.5 refers to tiny, toxic airborne particles that can penetrate deep into the lungs and bloodstream.
According to the report, residents of Rautahat, Mahottari, and Bara districts in the central and eastern Terai face the most toxic air. If pollution there were reduced to WHO levels, people could live 5.2 years longer on average. At the provincial level, Madhes is the most polluted, followed by Koshi, where life expectancy could increase by 3.6 years if air met global standards. Overall, for the 40 percent of Nepal’s population living in the central and eastern Terai, life expectancy could rise by 4.7 years. In Kathmandu, pollution has cut average lifespans by 2.6 years.
In 2023, Rautahat recorded the nation’s highest PM2.5 concentration at 59.5 micrograms per cubic metre, followed by Mahottari (59.2) and Bara (58.9). The study notes that between 1998 and 2023, Nepal’s PM2.5 levels rose by 74 percent, reducing life expectancy by 1.6 years.
Compared with other health risks, air pollution is deadlier. Smoking shortens life expectancy by 1.9 years in Nepal, while dietary risks cut it by 1.3 years.
The problem is not unique to Nepal. Across South Asia, pollution rose by 2.8 percent in 2023 compared to 2022, making the region the most polluted in the world. On average, it trims life expectancy in South Asia by 3 years. Globally, air pollution reduces life expectancy by 1.9 years, a threat comparable to smoking but far deadlier than alcohol, traffic accidents, or HIV/AIDS.
“Air pollution continues to rank as the top factor shortening lives across the world,” said Tanushree Ganguly, director of the Air Quality Life Index. She noted that many countries have historically improved air quality alongside economic growth. “Controlling fossil fuels at their source will not only clean local air but also help fight climate change. The most important step is having good knowledge about our own air quality.”
The institute publishes this report annually, with this year’s analysis based on 2023 data.