Your circulatory system is made of blood vessels that pick up oxygen from the lungs and distribute it to your muscles and organs. The chemicals in cigarette smoke damage your blood cells and blood vessels, disrupting this oxygen-delivery process, increasing your risk of diseases of the blood vessels and heart. This damage can also increase your chance of a blood clot, resulting in heart attack or stroke.
When you’ve been cigarette-free for a mere two hours, your circulation begins to improve.