Health Effects Institute: State of Global Air 2024
26 July 2024
A special report on global exposure to air pollution and its health impacts, especially on children.
Now in its fifth iteration, the State of Global Air 2024 draws upon the best available air quality data, estimates of health risks, and demographic data to produce globally comparable, country-level information on exposures to common air pollutants including fine particulate matter (PM₂.₅), ozone, and for the first time, nitrogen dioxide (NO₂). The 2024 report covering 1990 - 2021 is produced in partnership with UNICEF and includes a focus on children’s health.
The State of Global Air 2024 finds that:
Air pollution accounted for 8.1 million deaths globally in 2021, becoming the second leading risk factor for death.
Of the total deaths, noncommunicable diseases including heart disease, stroke, diabetes, lung cancer, and chronic obstructive pulmonary disease (COPD) account for nearly 90% of the disease burden from air pollution.
A significant proportion of the estimated deaths due to air pollution (38%) are due to exposure to household air pollution – which is from cooking food with solid fuel.
In 2021, more than 700,000 deaths in children under 5 years were linked to air pollution; this represents 15% of all global deaths in children under five. Most of these (more than 500,000 deaths in children under five) were linked to household air pollution from cooking with solid fuels.
The State of Global Air 2024 utilises data from the Global Burden of Disease (GBD) 2021 study. A quick comparison of the estimated PM₂.₅ concentration and impacts with HAPINZ 3.0 results for New Zealand shows that:
The population weighted average PM₂.₅ concentration in State of Global Air 2024 (6.83 micrograms per cubic metre, µg/m³) is similar to HAPINZ 3.0. (6.5 µg/m³) for 2016.
The estimated number of deaths attributable to PM₂.₅ is lower in the State of Global Air 2024 (458) compared with HAPINZ (1,300) for 2016.
The GBD study uses non-linear, cause specific exposure-response functions. This is quite different to the HAPINZ 3.0 study which estimated all-cause mortality based on a New Zealand cohort study.
A quick comparison of the estimated NO₂ concentration in State of Global Air 2024 with HAPINZ 3.0 results for New Zealand shows that:
The population weighted average NO₂ concentration is lower in the State of Global Air 2024 (6.21 µg/m³) compared with HAPINZ 3.0. (7.8 µg/m³) for 2016.
The State of Global Air 2024 estimates years lived in disability (YLD). For context, one YLD represents the equivalent of one full year of healthy life lost due to poor health. This is not directly comparable to HAPINZ, which quantified asthma prevalence in children. For example:
The State of Global Air 2024 estimated that childhood asthma linked to NO₂ exposure resulted in 16.1 YLD for New Zealand in 2010 and 9.76 YLD in 2021.
HAPINZ 3.0 estimated 13,229 cases of childhood asthma in 2016 associated with NO₂ exposure.
The State of Global Air 2024 assesses the impact of NO₂ on childhood asthma. Other impacts of NO₂ (including premature mortality) are not assessed.
Air pollution and burden of disease data by country and region can be explored in an interactive app.
This comparison graphs age-standardised premature mortality per 100,000 attributed to annual PM₂.₅ exposure in New Zealand (yellow dots) vs the USA (blue dots) for the period 1990 - 2021.
The difference in premature mortality rates in 2020 (increase in the USA and decrease in NZ) likely reflects the different impacts of the COVID-19 pandemic.
Of note, the State of Global Air 2024 provides some thought-provoking conclusions:
Rising temperatures are worsening air pollution and its health effects, underscoring the urgent need for integrated action to simultaneously improve air quality and reduce greenhouse gas emissions. Just in the last year, wildfires, extreme heatwaves, and more frequent and severe dust storms have proven to be devastating to air quality in regions around the globe.
Climate change can exacerbate the health burden of non-communicable diseases. For example, the number of deaths related to heart and lung diseases has been found to increase during heatwaves, which are becoming more common as the planet warms. Although this trend is alarming, the flip side is that by reducing air pollution we can achieve health gains, simultaneously helping to slow climate change, prevent pollution-related illnesses, and curb the interactions that exacerbate the impacts of both.
Even with improvements in air quality, the burden of disease attributable to air pollution continues to rise as populations grow, age, and become more susceptible to the noncommunicable diseases most closely related to air pollution.
The State of Global Air 2024 report has a companion interactive website with tools to explore, compare, and download data and graphics. Anyone can use the website to access data for cities and countries around the world and track long-term trends for air pollutants and associated health impacts at www.stateofglobalair.org.