What's Polluting Our Air?

Globally, most major sources of air pollution:

  1. Are caused by human activity.
  2. Involve burning fossil fuels or biomass.



Power plants

Industrial activities

Cooking and heating




Common sources of air pollution.


Major sources of PM2.5 vary substantially by country, with notable contributions from energy generation, industry, transportation, windblown dust, and agriculture sectors in certain locations. Since a majority of PM2.5 in outdoor air comes from anthropogenic fuel combustion, suggesting that integrating air quality, energy, and climate policies is likely to bring substantial health benefits.

  • PM2.5

    In 2019, fine particulate matter pollution contributed to 4.14 million deaths worldwide. Today, 99% of people on Earth are exposed to levels of PM2.5 pollution above the recommended WHO guidelines.

  • Ozone

    Ozone is a secondary pollutant formed by chemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight. Learn more about ozone and your health.

  • Nitrogen Dioxide

    Nitrogen dioxide (NO2) is a pollutant generated mainly through the burning of fuels in vehicles, power plants, and industrial facilities. Learn more about (NO2) and your health.

  • Household Air Pollution

    Household air pollution comes primarily from burning solid fuels for inside homes for cooking or heating. Learn more about household air pollution and its associated health impacts.