Regular exposure to even low levels of air pollution may cause changes to the heart similar to those in the early stages of heart failure, experts say. 　　A study of 4,000 people in the UK found those who lived by loud, busy roads had larger hearts on average than those living in less polluted areas. 　　A team of scientists, led from Queen Mary University of London, analysed health data of people who had no underlying heart problems, including the size, weight and function of their hearts. 　　Dr Aung said, "Doctors and the general public all need to be aware of their exposure when they think about their heart health, just like they think about their blood pressure and their weight." 　　Dr Aung said the changes in the heart were small and potentially reversible. But he said the fact any change at all was detectable suggested even relatively low levels of air pollution may have a harmful effect on health.