Wildfires in France and Spain have exposed millions of people to health-damaging air pollution over the last few days, scientists said on Thursday.
Smoke from fires contains a mix of pollutants that reduce air quality even hundreds of kilometers away. Scientists said they were particularly concerned about emissions of fine particulate matter, known as PM2.5, which is associated with cardiovascular diseases, lung cancer and respiratory problems.
"We know that this has a really major health effect, particularly when there's exposure over multiple days," said Theodore Keeping, a climate scientist at Imperial College London.
"We're seeing increasingly severe and frequent high-intensity fires where people are exposed to these very, very high levels of PM2.5."
In the French city of Bordeaux, levels of PM2.5 pollution soared to peaks of above 300 micrograms per cubic meter on July 26, data from the EU's Copernicus Atmosphere Monitoring Service showed. Keeping said Bordeaux's PM2.5 levels had averaged 115 micrograms on July 26 - nearly five times the EU's average daily limit.
Smoke plumes spread unusually high PM2.5 levels downwind of Madrid and Bordeaux. In Limoges, a city more than 200 kilometers (125 miles) northeast of Bordeaux, PM2.5 levels peaked at above 400 micrograms per cubic meter over the weekend.
"They are producing huge amounts of smoke... we see it spreading out across central parts of Spain, southern France," said Mark Parrington, a senior scientist at the European Center for Medium-Range Weather Forecasts.
Wildfires can make PM2.5 even more dangerous, increasing the particles' toxicity as they combine with other components in smoke.
"It can also have a lot of other very unpleasant things condensed onto the particles which, being smaller in size, are the ones that can really get into the lungs and affect respiratory illness," Parrington said.
He urged people in affected areas to follow local authorities' advice, for example by keeping windows closed, staying indoors, or wearing masks.
CARBON DIOXIDE EMISSIONS
Climate change is intensifying the hot, dry conditions that allow wildfires to spread faster and burn longer.
Wildfires themselves make it harder to fight climate change. Europe's forests absorb and store hundreds of millions of tons of planet-heating carbon dioxide, which are released back into the atmosphere when the forest burns.
Wildfires in Europe have emitted 18 millions of metric tons of CO2 this year, with France logging its highest fire CO2 emissions on record for this point in the year, data from the European Forest Fire Information System showed. Half of the EU's fire emissions this year occurred in the last week alone.
Wildfires contribute a small fraction of the EU's total greenhouse gas emissions, but the EU also counts CO2 stored by forests towards its emissions-cutting targets, to compensate for pollution from industries.
Scientists said fire emissions this year had not reached a scale that would thwart climate targets - but that this could change, as climate change expands fire risk into northern countries with large CO2-storing forests.
"Once we start seeing fire weather conditions that cause large fires in those regions, where that's a large part of their net zero target, then that would be more of an issue," Keeping said.
