Smoking is one of the leading causes for heart attacks, heart disease and lung diseases not just in the United States, but also around the world. Aside from the uphill battle against the terrible addiction, once a smoker stops doing so, there are several benefits that start taking effect. Some of these will take days, weeks and even years, but there are two that happen almost immediately. The first one, is that almost 12 hours after the last cigarrette, the levels of carbon monoxide reduce within the human body, which means an initiation of the cleansing process. The second, and most important benefit that follows immediately is that, within 24 hours, the probability of suffering a heart attack from smoking reduces enormously, as heart rate and blood pressure respond within a few hours of the last cigarrette.