Where does the data for the State of Global Air come from?
The data used in the State of Global Air resources are developed as part of the Institute for Health Metrics and Evaluation’s (IHME) annual Global Burden of Disease (GBD) study, a systematic, scientific effort to quantify the magnitude of health loss from all major diseases, injuries, and risk factors by age, sex, and population. Note that these are scientific estimates developed through use of a wide range of data sources including air quality data available through the WHO Ambient Air Quality Database, census data, demographic and health surveys, disease prevalence studies and other sources. Explore all data inputs here.
What pollutants are included in the State of Global Air? Is there data for other pollutants, for example, SO2, black carbon, etc.?
The State of Global Air provides data on ambient PM2.5, ambient ozone, nitrogen dioxide (NO2) and household air pollution associated with the use of solid fuels for cooking.
Data on other pollutants not included in the State of Global Air (e.g., sulfur dioxide, and black carbon) are available on other sites, such as the WHO Ambient Air Quality Database, OpenAQ, the United States National Aeronautics and Space Administration (NASA), and NASA’s Health and Air Quality and Applied Sciences site (HAQAST).
Why do the estimates for health impacts of air pollution from State of Global Air/Global Burden of Disease study vary compared to other reported estimates such the WHO or European Environment Agency?
Air pollution mortality and burden estimates rely on three primary inputs: levels of exposure to a pollutant, exposure-response functions that describe the relative risks associated with different levels of air pollution (derived from epidemiological studies), and baseline mortality rates. Additionally, to calculate burden estimates, a counterfactual level of exposure—where risk is minimized—is typically defined. Variations in these inputs largely account for the differences observed in burden estimates. However, it is important to note that despite the differences, all the estimates point towards a large burden of disease for air pollution.
How are exposures for air pollutants determined as part of the GBD study?
GBD estimates of population-weighted exposure to ambient air pollution combine satellite-based estimates with chemical transport models and ground-level monitoring data (e.g., WHO Ambient Air Quality Database). However, the lack of ground-level monitoring data from many low- and middle-income countries contributes uncertainty to estimates from those critical regions. For details on the methodology, please refer to Appendix I of the State of Global Air 2024 report.
Why are long-term exposures to air pollution used to determine health impacts of air pollution?
Current GBD estimates are based on studies of long-term exposure because they provide the most complete evidence on levels and trends in annual disease burden and mortality attributable to air pollution. However, with growing severity and duration of episodes of high air pollution linked to climate change in many global regions, such as wildfires and sand and dust storms, more research is needed to understand how these short-term exposures might contribute to long-term average exposure and rates of disease/mortality.
Does PM2.5 from different sources have different health effects?
When estimating health impacts for PM2.5, we assume equitoxicity i.e., PM2.5 from all sources have similar relative toxicity; this is in line with the current global understanding on the issue of PM2.5 and consistent with the approach taken by organizations including the World Health Organization and US Environmental Protection Agency, formulating their guidelines and standards for mass concentration of PM2.5. This issue remains an active area of research and is a source of uncertainty in the estimates.
How can I find results for my country?
The interactive portion of the State of Global Air site contains data for individual countries. Go to Explore the Data and select your country from the “Choose a country” dropdown menu. See further instructions on the How To page.
Why might the health effects of air pollution be more severe in some communities?
Factors including socioeconomic status, race, gender, sex, occupation, and other social determinants of health play a significant role in the severity of illness experienced because of exposure to air pollution. For example, studies have reported that poor and historically marginalized communities, who often have increased vulnerability to poor health, are often the ones with higher exposure to air pollution. Global data also shows that the largest health impacts related to air pollution are seen among children and older people. Thus, the trends for burden of disease related to air pollution are linked not only to the levels of exposure to air pollutants, but also the population structure and underlying health status of the population. For example, in an aging population, the burden of disease can be high despite relatively lower levels of pollution; this is because of the higher susceptibility to diseases among older people.
Where can I find daily air quality data for my country or city?
You can find detailed real-time air quality data for many worldwide locations at the following websites:
Aqicn.org Air Pollution: Real-time Air Quality Index, has current air quality and forecasts for 5 pollutants and 4 weather variables, with maps of nearby monitors.
Openaq.org Open, Real-time Air Quality Data is an open-source platform for real-time and historical, publicly available outdoor air quality data that are available for downloading in a universal data format.
How can I make sure that the air quality monitoring data from my country is included in the GBD air pollution analysis?
One of the major sources for air pollution data used in the GBD initiative is the WHO Global Ambient Air Quality Database. Official air pollution monitoring results can be uploaded online following directions on the site. The database is updated every 2 years. If there are specific data you’d like to share for the purposes of this project, please contact us via contactsoga[at]healtheffects[dot]org. Data available through OpenAQ are also used for developing the pollution exposure estimates shared on the State of Global Air website.
Can I use this website for teaching purposes?
Yes, please do! And we’d like to hear about it. Go to Contact and tell us how you used the data and your experience.
Where can I find data on the sources of PM2.5?
The data are available on the State of Global Air data application.
In December 2021, HEI published a research report, Global Burden of Disease from Major Air Pollution Sources (GBD MAPS): A Global Approach, which estimated source contributions to ambient PM2.5 at global, world region, and national scales using updated emissions inventories categorized by sector and fuel, satellite data and air quality modeling, and the most recent relationships between air quality and health. The study was conducted by Dr. Erin McDuffie and colleagues. Data from the analysis are publicly available on Zenodo. Furthermore, to ensure reproducibility, Dr. McDuffie’s team provided the statistical code for all analyses on GitHub. Detailed data and maps are also available through the authors’ website.
Can I use these data for my own research and publications? If so, how should I cite them?
We encourage the use of State of Global Air data in your work. Materials produced as part of State of Global Air are freely available for downloading, printing, and distribution without alteration, provided that proper credit is given, using the following citation:
Health Effects Institute. 2024. State of Global Air 2024. Available: www.stateofglobalair.org [accessed MM/DD/YYYY].
For the reports, please use the relevant citation provided on the pdf file.
Why are the estimates for fossil-fuel related deaths lower compared to other published estimates?
The State of Global Air uses the estimates from the HEI Research Report 210 for sources of PM2.5 and the associated health impacts. For 2019, the analysis reported 1.05 million (UI: 0.74-1.36 million) deaths linked to fossil fuel combustion. In comparison, Vohra et al. (2021) estimated 10.2 million deaths (Uncertainty Interval: -47.1-17.0) per year from fossil fuel combustion, using 2012 as the base year. The higher estimates from Vohra et al. study are likely due to the choice of concentration-response functions used in the study (use of a meta-analysis), and use of all-cause mortality for the health assessment. For reference, GBD uses cause-specific mortality for estimating the disease burden.
Why are the life expectancy losses attributed to air pollution reported in the State of Global Air lower than other estimates from the Air Quality Life Index reported by the University of Chicago?
The difference lies in the underlying scientific evidence and approach used to make the estimates. To estimate the loss of life expectancy resulting from air pollution, one needs age-specific mortality rates and a quantitative measure of the relation between exposure and its effects on health. The State of Global Air reports data on loss in life expectancy based on data and methods from the Global Burden of Disease project. The pollution exposure–response relationships used in the GBD are based on systematic reviews of the world’s literature and a broad set of observational epidemiological studies of exposure to combustion-related particles. This analysis additionally incorporates country-specific demographic and epidemiological data that affect baseline survival rates. The University of Chicago study relies on observed relationships between air pollution and life expectancy derived from a set of two peer-reviewed quasi-experimental studies of air pollution and mortality conducted in China.
How often is the data for the State of Global Air updated?
The website is regularly updated to reflect the most recent IHME Global Burden of Disease study results.
Can I subscribe to updates?
If you are interested in receiving updates about the State of Global Air, scroll down to "Sign up for updates" at the bottom of the page and enter your contact information. You can also visit our Contact page. You will receive a confirmation email and you may opt out at any time you want.
