Scientists from the Yale School of Public Health have found that even a few hours’ exposure to ambient ultrafine particles common in air pollution may potentially trigger a nonfatal heart attack. Myocardial infarction is a major form of cardiovascular disease worldwide. Ultrafine particles are 100 nanometers or smaller in size. In urban areas, automobile emissions are the primary source of UFP. “This study confirms something that has long been suspected,” says researcher Kai Chen. “Air pollution’s tiny particles can play a role in serious heart disease. This is particularly true within the first few hours of exposure. Elevated levels of ultrafine particles are a serious public health concern.” The study is believed to be the first epidemiological investigation of the effects of ultrafine particles exposure and heart attacks using the number of particles and the particle length and surface area concentrations at hourly intervals of exposure.