Narrator: This is Science Today. You may have noticed that being around second-hand smoke can irritate your nose and eyes and can often lead to headaches, but are you aware of what happens to your heart? Dr. Stan Glantz, a professor of medicine at the University of California, San Francisco, explains how exposure to the toxic chemicals in second-hand smoke increases your risk for a heart attack.Glantz: A cigarette is like a little toxic waste dump on fire. It puts into the air a huge number of toxic chemicals. They very severely affect your blood and your blood vessels. They activate blood platelets, which makes your blood get sticky and stick to the walls of your arteries. And they also inhibit the ability of your arteries to expand, when they need to expand to get more blood to your heart and other parts of your body. And both of these things increase your risk of a heart attack. And these are effects that occur within minutes. Narrator: Glantz recently published a study proving that creating smoke-free environments lowers the number of heart attacks in a population. For Science Today, I'm Larissa Branin.