With ever increasing numbers of deaths resulting from heart disease and heart attacks, environmental cardiology has become a popular field of study. After roughly 16 years of research these cardiologists may have found a link between heart disease and air pollution. The study encompassed roughly 250 cities worldwide, where increased air pollution was said to have incited heart attacks. Research from the relatively new field of environmental cardiology includes a 16-year-long Harvard University study of six U.S. cities that found fine particulate pollution, even at levels below the federal health standard, can shorten lifespans by two years. A majority of these earlier deaths were due to heart disease. Those who were more susceptible to such ailments were among the older demographics or those who had previously had heart problems. Likewise people with diabetes and obesity (all of which are high-risk people) may also be more likely to be victim to these issues.