Most polluted countries based on PM2.5 concentration globally 2024

Chad was the most polluted country in the world in 2024, with an average annual PM2.5 concentration of 92 micrograms per cubic meter of air (µg/m3). These levels were around 18 times above the World Health Organization guideline. Major sources of PM2.5 include residential fuel burning, road vehicles, and power plants.

What are PM2.5 pollutants

PM2.5 refers to fine particles that have a diameter of 2.5 micrometers or less. These tiny, light, and inhalable pollutants can stay in the air for long periods of time and are a considerable risk to human health when concentrations are high. There were an estimated eight million premature deaths linked to air pollution worldwide in 2021, of which 60 percent were attributed to ambient PM2.5.

Pollution in cities

In 2024, N'Djamena, Chad and New Delhi, India were the most polluted capital cities in the world, with average annual PM2.5 concentrations of 92 µg/m³. In 2024, 11 of the 20 most polluted cities worldwide were in India, the most polluted of which recorded PM2.5 levels 25 times above WHO standards.