Scientists from Yale University have revealed that even an hourly exposure to the ultrafine particles that are commonly present in the polluted air may increase the risk of a nonfatal heart attack. Ultrafine particles (UFP) primarily produced by automobile emissions , pose a health threat due to their minute size and their ability to affect the blood system. The study involved 5, 898 nonfatal heart attack patients between 2005 and 2015. Researchers performed the study by comparing heart attack cases with air pollution UFP data on the hour of the heart attack. Scientists consider this research important to understand the detailed role of ultrafine particles exposure to cause short-term health effects.