Millions of people across France and Spain have faced hazardous air pollution as Wildfire Smoke from large forest fires spread across southern Europe, scientists warned on Thursday. Experts said the smoke contains dangerous fine particulate matter, known as PM2.5, which can travel hundreds of kilometres and significantly increase the risk of heart disease, lung cancer, and respiratory illnesses.

Climate scientists said prolonged exposure to PM2.5 poses a serious public health threat, especially as climate change fuels more frequent and intense wildfires. Theodore Keeping, a climate scientist at Imperial College London, said communities are experiencing increasingly severe smoke pollution for several consecutive days.

More than 100 words into the crisis, Wildfire Smoke has pushed air quality to alarming levels across parts of France and Spain. Data from the European Union’s Copernicus Atmosphere Monitoring Service showed PM2.5 concentrations in Bordeaux exceeded 300 micrograms per cubic metre on July 26. Keeping said the city’s average PM2.5 level reached 115 micrograms that day, nearly five times higher than the European Union’s recommended daily limit.

Smoke plumes also carried dangerous pollution across central Spain and southern France. In Limoges, located more than 200 kilometres northeast of Bordeaux, PM2.5 levels climbed above 400 micrograms per cubic metre during the weekend.

Hezbollah Tunnels Destroyed as Israel Unleashes Massive Blasts Across Southern Lebanon

Mark Parrington, a senior scientist at the European Centre for Medium-Range Weather Forecasts, said the fires generated massive amounts of smoke that spread across large parts of the region. He warned that wildfire particles become even more harmful when they combine with other chemicals in smoke, allowing toxic particles to penetrate deep into the lungs.

Scientists urged residents in affected areas to follow official health guidance by staying indoors, keeping windows closed, reducing outdoor activities, and wearing protective masks when necessary.

Experts also warned that climate change continues to intensify the hot and dry conditions that allow wildfires to spread faster and burn longer. Rising temperatures have increased both the frequency and intensity of destructive fires across Europe.

Beyond the immediate health risks, wildfires are releasing enormous amounts of carbon dioxide into the atmosphere. Europe’s forests normally absorb and store hundreds of millions of tonnes of carbon dioxide, but burning forests release those stored emissions back into the atmosphere, accelerating global warming.

According to data from the European Forest Fire Information System, wildfires across Europe have released around 18 million metric tonnes of carbon dioxide this year. France has already recorded its highest wildfire-related carbon emissions ever measured at this stage of the year. Nearly half of the European Union’s total wildfire emissions occurred during the past week alone.

Although wildfire emissions currently represent only a small share of the European Union’s total greenhouse gas emissions, scientists warned that the situation could worsen if climate change expands wildfire risks into northern Europe, where vast forests play a critical role in meeting net-zero climate targets.

Researchers said protecting forests from increasingly severe wildfires will become essential for both public health and Europe’s long-term climate strategy.