A little known greenhouse gas is quietly harming half of Europeans. This Italian city is hit hardest

Summer heat and wildfires push ozone pollution across Europe

Poinews.com – Europe’s record-breaking summer heat and widespread wildfires brought an often overlooked health threat into focus: ground-level ozone. From June through August 2026, half of the continent’s population encountered ozone concentrations rated poor, very poor or extremely poor by the European Commission’s Copernicus Atmosphere Monitoring Service (CAMS).

Unlike the protective ozone layer high in the atmosphere, ground-level ozone is a harmful air pollutant. It develops near the surface when sunlight and intense heat drive complex chemical reactions involving pollutants already present in the air. Thousands of reactions can contribute to its formation, making hot, stagnant summer conditions especially favourable for dangerous spikes.

The 2026 heatwaves created precisely those conditions. As temperatures climbed across Europe, ozone levels rose to concentrations that can endanger health, particularly in the continent’s warmer southern regions. The pattern reinforces a difficult reality: climate change and air pollution are not separate problems, but forces that can intensify one another.

A pollutant that reaches beyond the lungs

Ground-level ozone can travel deep into the respiratory system and enter the bloodstream, allowing it to affect nearly every organ in the body. People living with asthma face particularly high risks, but exposure can also be a concern for others during severe pollution episodes, especially when they spend prolonged periods outdoors in hot weather.

Air pollution is frequently described as an invisible killer. The World Health Organization links it to more than four million premature deaths around the world each year. In Europe and Central Asia, air pollution was associated with 56 deaths for every 100,000 people in 2025.

Ozone is less familiar to many people than fine particles or nitrogen dioxide, yet it deserves attention because of its direct relationship with rising temperatures. CAMS describes ground-level ozone as a clear illustration of the connection between air quality and climate change, since elevated temperatures help trigger its creation.

“Ozone pollution is a stark reminder of how interconnected our atmosphere, climate, health, and livelihoods really are, with pollution and our changing climate impacting the chemistry of the air we breathe, determining the health of our ecosystems, and even governing our ability to grow food,” says Laurence Rouil, Director of CAMS.

Human-driven climate change is increasing global temperatures and making heatwaves both more common and more severe. Because ozone formation accelerates in high heat, this trend can mean more frequent episodes of unhealthy air. That makes it harder to treat ozone solely as a traditional air-quality issue; it is also part of the climate challenge.

Where the chemicals come from

Nitrogen oxides play a major role in the chemical processes that produce ozone. These pollutants are mainly created by burning fossil fuels. Industry, road traffic and solvents are among the principal sources linked to ozone formation. Biomass burning adds another pressure, particularly when hotter and drier conditions contribute to more extreme fires.

Ozone itself also contributes to warming. The UK charity Clean Air Fund estimates that it accounts for roughly 0.23°C of today’s warming and describes it as a “super pollutant.” This creates a troubling feedback loop: hotter conditions support ozone production, while ozone adds to the warming that makes heat extremes more likely.

The impacts are not limited to human health. Ozone pollution can affect ecosystems and agriculture, with the chemistry of the air influencing the ability to grow food. During heatwaves, these combined pressures can become especially significant because people, crops and natural environments are all coping with high temperatures at the same time.

Progress on other pollutants, but ozone remains stubborn

There are encouraging signs in Europe’s broader campaign to improve air quality. CAMS’s Atmosphere Watch report notes substantial progress for pollutants covered by the European Air Quality Directive. The EU’s 2024 directive requires member states to monitor pollutant limits and take action when safe thresholds are exceeded.

Emissions of sulphur oxides and nitrogen oxides across the European Union have fallen by roughly three to five per cent annually over the past decade. Industry and road transport have delivered the largest reductions. Since 2015, industrial sulphur oxide emissions have dropped by 59 per cent, while nitrogen oxide emissions from industry have declined by 39 per cent.

Road transport has also reduced its pollution output considerably, with nitrogen oxide emissions down 40 per cent and fine particulate matter, known as PM2.5, falling 34 per cent. These reductions show that regulation, cleaner technology and changes in how energy and transport systems operate can have measurable effects.

Yet ozone has not followed a similarly clear downward path. Atmosphere Watch warns that it remains an unresolved problem, even as other regulated pollutants improve. Its dependence on heat and sunlight helps explain why cutting emissions alone can be more complicated when summers are becoming hotter.

What counts as unsafe ozone exposure?

Under the EU Ambient Air Quality Directive, the maximum eight-hour average concentration of ozone should stay below 120 μg/m3 on all but 18 days in a year. The longer-term goal is 100 μg/m3, in line with World Health Organization guidance. Monitoring in 2026 has shown that many parts of Europe have already exceeded these benchmarks, with conditions generally worsening further south as heatwave intensity increases.

Reducing ozone requires sustained action on the pollutants that feed its formation as well as on the emissions driving climate change. Measures seen as effective include stronger public transport, low- and zero-emission traffic zones, replacing fossil fuels with clean energy, and reducing meat consumption.

For residents, ozone episodes underline the value of checking local air-quality information during heatwaves, particularly for people with asthma and other respiratory concerns. Hot weather may be associated with bright skies and time outdoors, but it can also alter the air in ways that are not visible.

Europe’s improvements in industrial and traffic emissions demonstrate that action can work. The continuing ozone challenge, however, shows that protecting public health will require policies able to address both the pollution produced today and the hotter climate that helps turn it into a more dangerous pollutant.