Estimates of the burden of disease from air pollution on this website come from the Global Burden of Disease (GBD) project of the Institute for Health Metrics and Evaluation (IHME). Find more details on our methodology in the State of Global Air report.

Which Health Effects Are Included?

The GBD’s estimation of the burden of disease begins with a systematic evaluation of the global scientific evidence and whether it is strong enough to attribute a given health outcome or cause of death to a particular pollutant. Every risk–outcome pair in the GBD undergoes this rigorous evaluation.

In the GBD analyses, health effects attributable to long-term exposure to PM2.5 and household air pollution are ischemic heart disease, lung cancer, chronic obstructive pulmonary disease (COPD), lower-respiratory infections (such as pneumonia), stroke, type 2 diabetes, and adverse birth outcomes. For ozone, COPD is the only health effect included in the analyses. Learn More.

How We Calculate Impacts

The GBD project calculates each pollutant’s burden of disease in each country using:

  • Mathematical functions, derived from epidemiological studies from countries around the world, that relate different levels of expo­sure to the increased risk of death or disability from each cause, by age and sex, where applicable,
  • Estimates of population exposure to PM2.5, ozone, and household air pollution,
  • Country-specific data on underlying rates of disease and death for each pollution-linked disease, and
  • A comprehensive set of population data, adjusted to match the UN2015 Population Prospectus and obtained from the Gridded Population of the World (GPW) database for each country.

The results of these calculations are expressed in several ways: 

  • Total number of deaths: The number of deaths in a given year attributable to air pollution that likely occurred earlier than would be expected in the absence of air pollution.
  • Disability-adjusted life-years (DALYs): The sum of the years of life lost from early deaths plus the years lived with a disability, such as paralysis from a stroke related to air pollution exposure.
  • Age-standardized rates: The total number of deaths or DALYs per 100,000 people, calculated based on a standard distribution of population across age categories. Age-stan­dardized rates allows direct comparison of the health burden among countries with very different population sizes and distributions of ages in the population. Higher air pollution-attributable age-standardized rates of disease reflect a combination of higher air pollution levels and/or sicker populations. 
  • Loss of life expectancy at birth: The difference in years between a person’s expected lifespan and the length of life that would be expected if air pollution were not present.

Estimates of scientific uncertainty are provided for every value in the form of 95% uncertainty intervals (UIs), representing the range between the 2.5th and 97.5th percentiles of the distribution of possible values.

For more details, please refer to the GBD risk factors paper published in The Lancet. If you have data from your city or country that you would like to have included in the Global Burden of Disease project, please contact us at contactsoga@healtheffects.org.