Most polluted countries based on PM2.5 concentration globally 2023

Bangladesh had an average PM2.5 concentration of nearly 80 micrograms per cubic meter of air (µg/m3) in 2023, becoming the most polluted country in the world. This was over 25 µg/m³ more than the average PM2.5 concentration in India. The high levels of pollution in Bangladesh can be explained by the country's persistent traffic, construction activities, and industrial fumes – in particular from brick kilns, which are highly reliant on coal.

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 major risk to human health when concentrations are high. The World Health Organization advises that annual mean PM2.5 concentrations should not exceed 5 µg/m³. Major sources of PM2.5 include solid waste burning, road vehicles, and power plants.

Pollution in cities

In 2023, New Delhi was the most polluted capital city in the world, with an average PM2.5 concentration of 92.7 µg/m³. This was followed by the Bangladeshi capital, Dhaka. Despite these high PM2.5 levels, the most polluted city worldwide was Begusarai – in northeastern India – with an average PM2.5 concentration of nearly 119 µg/m³.