A new international assessment finds ground-level ozone causes 480,000 premature deaths annually, with the heaviest burden shifting toward developing regions.
RT’s Three Key Takeaways:
- Rising Global Mortality: Premature deaths linked to long-term exposure to ground-level ozone nearly doubled worldwide between 2000 and 2020, reaching an estimated 480,000 annual fatalities.
- Shifting Regional Disparities: While ozone concentrations declined across parts of North America and Europe because of strict emissions controls, exposure increased significantly across rapidly industrializing regions in the Global South.
- Severe Monitoring Gaps: Nearly 3 billion people lived in nations lacking adequate air quality monitoring in 2020, leaving acute surveillance blind spots in South Asia and Sub-Saharan Africa.
Premature deaths associated with long-term exposure to ground-level ozone nearly doubled across the globe between 2000 and 2020, reaching approximately 480,000 deaths annually, according to a global assessment published in Philosophical Transactions of the Royal Society.
The findings were released as part of the Tropospheric Ozone Assessment Report, Phase II (TOAR-II), which evaluated global trends in long-term ozone exposure and associated health outcomes using a worldwide database compiling observations from thousands of monitoring sites. Ground-level ozone is a hazardous pollutant that develops when emissions from vehicles, power plants, and industrial facilities react chemically in the presence of heat and sunlight, presenting persistent risks to respiratory and systemic health.
The report highlights a marked geographic divergence in exposure. According to the assessment, ozone concentrations and related healthcare burdens dropped across sections of North America and Europe due to technological advances, cleaner fuels, and regulations curbing nitrogen oxide emissions. In contrast, levels rose substantially throughout much of the rapidly industrializing Global South.
“Ozone pollution remains an important global health threat, and the burden is shifting toward regions that often have the fewest resources to monitor and address it,” said Gaige Kerr, lead author and assistant professor in the department of environmental and occupational health at the GW Milken Institute School of Public Health. “Our findings show that reducing ozone precursor emissions can protect health, but we need much stronger monitoring and pollution controls in regions where ozone exposure is rising.”
Global Disparities and Surveillance Deficits
In their analysis of global observations and modeled exposure metrics between 2000 and 2020, the study authors identified the highest recent ozone levels in South Asia, eastern China, and sections of the Middle East and North Africa.
Despite an overall 32% expansion in monitoring infrastructure since the initial TOAR assessment, the report documented substantial surveillance deficits. The TOAR-II database captured data from 6,335 monitors located across only 59 of 225 countries and territories. As a result, an estimated 3 billion individuals—representing 38.6% of the global population in 2020—resided in areas without adequate monitoring, with the most pronounced gaps identified in South Asia and Sub-Saharan Africa.
Long-Term Health Risks and Climate Pressures
The assessment also evaluated epidemiological methodologies used to quantify health damage from ozone, warning that future climate conditions could exacerbate the respiratory toll. Shifts in atmospheric temperature and air circulation patterns are expected to accelerate ozone formation and dispersion.
According to projections cited in the report, annual premature deaths attributable to ozone could escalate to between 2 million and 3.5 million by 2100 if substantial reductions in greenhouse gases and precursor emissions are not implemented. To mitigate the projected rise in global mortality, the author team called for broadened surface monitoring networks, improved epidemiological tracking, enhanced exposure modeling, and sustained curbs on industrial precursor emissions.
