'Four times more toxic': How wildfire smoke ages over time

As the trees, shrubs, grass and peat are engulfed by these fires, huge quantities of smoke, soot and other pollutants are released into the air. With large fires, the smoke can rise many kilometres into the stratosphere and spread across entire regions, causing air pollution in areas far away from where the flames actually were. 'In the eastern Mediterranean we get smoke that blows down from forest fires in Russia and when it happens there is just hazy smoke everywhere,' said Professor Athanasios Nenes, an atmospheric chemist at the Institute of Chemical Engineering Sciences in Patras, Greece. 'It can be quite dramatic. They are affecting air quality over entire regions or parts of continents.'