Researchers found stronger evidence about the lifelong harm from air pollution: i.e., the air breathed as children can stunt the growth of lungs, potentially causing problems later in adult life.
Investigating lifelong impacts is not easy because of the lack of historic measurements, therefore scientists found a solution with the help of the natural environment. They built a 135-year model of pollution in the United States by studying soot in the feathers of museum bird specimens.
Tests on more than one thousand birds show an air pollution between 1880 and 1920 higher than expected. It also reveals useful data for climate scientists: the level of soot pollution decreased around 1910, dropped in the Great Depression and raised during the second world war.