Nepal has been ranked as the world’s seventh most polluted country in the World Air Quality Report 2024 by Swiss air quality firm IQAir. The country recorded an average PM2.5 concentration of 42.8 µg/m³ in 2024, up from 42.4 µg/m³ in 2023, exceeding the World Health Organisation’s ( WHO) annual average PM2.5 guideline of 5 µg/m³ by more than eight times.
PM2.5 refers to fine particulate matter of 2.5 microns or smaller in diameter, which can penetrate deep into the lungs and enter the bloodstream, impacting major organs. According to the WHO, exposure to PM2.5 increases the risk of cardiovascular and respiratory diseases, including stroke, lung cancer, and chronic obstructive pulmonary disease (COPD).
The report, published on March 11, analyzed PM2.5 pollution levels in 8,954 cities across 138 countries, regions, and territories, using data from over 40,000 air quality monitoring stations worldwide.
Global Pollution Rankings
Chad topped the list as the world’s most polluted country, with an average PM2.5 concentration of 91.8 µg/m³, followed by Bangladesh (78 µg/m³) and Pakistan (73.7 µg/m³). The Republic of Congo, India, and Tajikistan secured the fourth, fifth, and sixth spots, respectively. Uganda, Rwanda, and Burundi rounded out the top ten.
Read: Majority of the World's Population Breathes Dirty Air: Report
Among the world’s most polluted cities, Kathmandu ranked 193rd , with an average PM2.5 concentration of 45.1 µg/m³. In five months of 2024—January, February, March, April, and December—the city’s PM2.5 levels exceeded WHO’s safe limit by over 10 times, the report noted. April recorded the worst pollution level at 86.9 µg/m³, while the lowest level was 9.9 µg/m³ in August.
Byrnihat (India) and Delhi were named the world’s two most polluted cities, with average PM2.5 concentrations of 128.2 µg/m³ and 108.3 µg/m³, respectively. Karaganda (Kazakhstan), Mullanpur (India), and Lahore (Pakistan) completed the top five.
Notably, 13 of the 20 most polluted cities were in India, highlighting severe air quality concerns in the region.
The report says only 17% of global cities met WHO’s air pollution guidelines. Seven countries—Australia, the Bahamas, Barbados, Estonia, Grenada, Iceland, and New Zealand—met WHO’s annual average PM2.5 guideline of 5 µg/m³, setting a benchmark for cleaner air worldwide.
