List of most-polluted cities by particulate matter concentration

This list contains the most-polluted cities by PM2 annual mean concentration measurement as documented by the World Health Organization (WHO) covering the period from 2019 to 2022. The January 2024 version of the WHO database contains results of ambient (outdoor) air pollution monitoring from almost 5,390 towns and cities in 63 countries. Air quality in the database is represented by the annual mean concentration of particulate matter (PM10 and PM2 , i ., particles smaller than 10 or 2 micrometers, respectively). Please note that constraints exist in this list as the WHO says these data are not comparable between countries. Data in this list are self-measured and self-reported so some places in Africa and South America which lack air pollution reporting tools are not properly reflected in this list. On the other hand, countries featured in this list with many cities may only mean that they have large and wide air pollution monitoring networks, rather than an indicator of heavy pollution.