ScienceDaily: A post-mortem study of the hearts of 21 young people in Mexico City has found that the heart begins to show the adverse effects of air pollution at a young age and that tiny bits of inactivated bacteria that hitch a ride on pollutants may make the problem worse. The study is part of a growing body of research showing that air pollution can damage the heart and lead to increased risk of heart disease and heart attacks. But this study contrasted two different areas of the same city, …