Scientists found that air pollution may be responsible for a big reduction in intelligence. Research conducted in China showed that air pollution was responsible for big falls in test scores for languages and arithmetic. The study is called, "The impact of exposure to air pollution on cognitive performance". It was published in the "Proceedings of the National Academy of Sciences" journal. The study took place over four years. Researchers analyzed speaking and arithmetic tests taken by 20,000 people of all ages. They said: "Polluted air may impede cognitive ability as people become older."
The study is a warning to the rest of the world, especially those in cities. Over 91 per cent of the world population live in areas with toxic air and air pollution is the fourth highest cause of global deaths. Researchers discovered that the longer people were exposed to polluted air, the greater their intelligence went down. They said air pollution caused a year's worth of lost education. For those aged over 60, this could be several years. A researcher warned: "There is no shortcut to solve this issue. Governments really need to take concrete measures to reduce air pollution."