The ‘super pollutant’ tropospheric ozone a serious health risk: new report
A little-known but highly toxic greenhouse gas known as tropospheric ozone harms human health and damages crops and forests, clean air experts told COP29.
(Baku, Azerbaijan) — A little-known but highly toxic greenhouse gas called tropospheric ozone poses a risk to human health and a threat to crops and forests, a group of researchers told delegates at COP29 on Thursday.
Tropospheric ozone is not emitted like many other gases and particles, but rather formed in the atmosphere when sunlight interacts with a suite of other pollutants including methane and nitrogen oxides, they explained.
Tropospheric ozone contributes to respiratory issues, reduces lung function, and can exacerbate chronic conditions like asthma, bronchitis and emphysema. It has also been linked to complications in type 2 diabetes and cardiovascular disease, they said.
The group of researchers — from the Clean Air Fund, Clean Air Institute, Clean Air Task Force and Hill Consulting — launched a new briefing at COP29 to raise awareness about the risks of tropospheric ozone and make policy recommendations.
“Tropospheric ozone creates health problems like respiratory issues and has contributed to 0.23°C of global warming so far,” Jane Burston, CEO of the Clean Energy Fund, told COP29 delegates.
“There’s huge opportunities for climate, health and economic development from tackling these things,” she urged.
Nine out of ten people are exposed to tropospheric ozone levels that exceed guidelines set by the World Health Organization (WHO), the research briefing says, contributing to almost half a million premature deaths each year.
“Meeting the WHO’s guidelines would save hundreds of thousands of lives and provide economic benefits of up to $500 billion per year, through avoided healthcare costs and a healthier, more productive workforce,” they urged.
Reducing tropospheric ozone levels would also help to avoid further global temperature rises in the coming decades, the study says.
Tropospheric ozone levels have increased significantly over the last century, the briefing notes. Since 1995, they have risen by between 2 percent and 12 percent per decade, depending on the region, driven largely by rapid industrialisation and urbanisation.
They are estimated to have contributed to 0.23°C of global warming from 1750 to the present, it added.
Cutting super pollutants, including tropospheric ozone, can mitigate warming nearly four times faster than decarbonisation alone, the researchers said.
Even though it’s one of the super pollutants driving half of global warming, dedicated action to reduce tropospheric ozone is “absent from the climate policy agenda at a global, regional, and country level,” they warned.
“There’s a real gap here for international leadership at the intersection of climate and health,” Tom Grylls, Head of Super Pollutants at the Clean Air Fund, told delegates.
Yet there are signs that significant actors in climate action are starting to wake up to this urgent issue, he said. “Just two days ago at COP, the U.S. and China held the non-CO2 summit, which I hope — alongside this report — is a real signal that this issue need to be elevated on the climate agenda.”
Among its policy recommendations, the briefing calls for global leaders at COP29 to push for tropospheric ozone and other non-CO2 pollutants to be included in the UN climate talks’ processes and reporting, building on the outcome of the UN’s 2023 Global Stocktake.
It also recommends countries joining and delivering on the Global Methane Pledge, a voluntary framework supporting nations to take action to collectively reduce methane emissions by 30% from 2020 levels by 2030.
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