According to a new details study on the impact of past air pollution on recent death rates, people who inhaled urban smoke and toxic fumes decades ago are still more likely to die of respiratory and heart disease. An individual who lived in a more highly polluted area in 1971 still had a 14 per cent higher risk of dying in 2002-09 than someone who had lived in a less polluted area, says Anna Hansell of Imperial College London, who led the study. Increased rates of bronchitis, emphysema, pneumonia and heart disease accounted for the extra deaths. The study tracked 368,000 people in England and Wales between 1971 and 2001, recording levels of smoke particles and sulphur dioxide in the air where they lived, and analysed how many of them died between 2002 and 2009. Although recent exposure turned out to be more dangerous than pollution inhaled in the past, pollution was around five times worse in the 1970s than today, the team found. As a result, someone who has been alive since then is just as likely to die from the effects of past pollution as they are from current pollution. Hansell says the study is a warning to countries like China that are prone to severe smog, the health toll of which will linger for decades. These findings make sense, says Frank Kelly of Kings College London. It is the cumulative impacts over many decades which result in tissue damage and increased susceptibility to more recent pollution episodes. These results will add to pressure on the UK government, says James Thornton of the environmental law campaign group ClientEarth. The government is currently violating the Supreme Courts order to clean up the air as soon as possible. The study shows that not only will citizens continue to die as we wait, but the population will continue to suffer increased mortality for decades, even after a clean-up. But there may be some good news. Because the effect of past pollution is so strong, it may have led to overestimates of how harmful todays air is, says Hansell. For younger people at least, that may reduce the health benefit of moving to the countryside. The risk of dying early is much more dependent, Hansell says, on whether you smoke and how much you exercise, as well as medical factors like blood pressure and whether you are overweight.
New Scientist, 9 February 2016 ;http://www.newscientist.com/ ;