What the evidence says about air pollution in Kathmandu Valley, what causes it, and what could help.
A research project by Prajina Shakya
Move the slider to a 24-hour average PM2.5 reading (µg/m³). The haze over the valley thickens as the number rises.
This tool only compares a number you choose with WHO levels. It does not show Kathmandu's actual air quality.
The World Bank's 2025 assessment links air pollution to about 26,000 premature deaths a year in Nepal and an average loss of 3.4 years of life expectancy. It estimates the economic cost at more than 6% of GDP annually.
These are national estimates, not figures for Kathmandu Valley alone. Kathmandu Valley and the Terai are named as Nepal's air-pollution hotspots.
World Bank press release (2025)PM2.5 particles are 2.5 micrometres across or smaller. They are small enough to reach deep into the respiratory system, and exposure is linked to adverse health outcomes. The WHO 2021 guideline levels are:
| Pollutant | Annual mean | 24-hour mean |
|---|---|---|
| PM2.5 | 5 | 15 |
| PM10 | 15 | 45 |
These are health-based reference levels, not measurements of Kathmandu's air.
WHO Global Air Quality Guidelines (2021)The World Bank points to vehicle emissions, industry, household cooking fuels, road dust and forest fires. Pollution also crosses municipal and national borders, so local action alone may not be enough.
The share of each source changes with place, season, weather and pollutant. This project does not assign percentages without source-specific data.
Towards Clean Air in Nepal (World Bank, 2025)Open Data Nepal publishes Air Quality Data in Kathmandu, covering 1 January 2015 to 13 March 2021. It includes PM2.5, PM10, ozone, sulfur dioxide and nitrogen dioxide.
Questions this dataset can help answer:
The data ends in March 2021, so it cannot describe current conditions. Any conclusion should name the period and locations it covers.
Open the datasetThe World Bank recommends coordinated action across sectors. Select a sector to see the approaches.
How well each approach works in a part of the Valley depends on how it is carried out, local conditions and measured results.
This is a secondary-research project. It reviews published institutional research, WHO guidelines and public data. It is not an original health study or a new measurement campaign.
Next steps: use recent, validated station data to compare levels over time, study seasonal patterns, and test whether local readings exceed WHO levels.
Air pollution is a serious environmental and public-health problem in Nepal, and Kathmandu Valley is one of its hotspots. It has many sources and needs coordinated responses, not a single fix.
Breathing Kathmandu brings together credible research, open data and honest statements of uncertainty, so that reliable information can support informed discussion and practical action for cleaner air.