Yes. Being around tobacco smoke is bad for you, even if it's someone else's smoke. When someone smokes a cigarette, most of the smoke doesn't go into their lungs. It goes into the air, where anyone nearby can breathe it.
Exposure to secondhand smoke raises your risk -- by as much as 30 percent -- of getting lung cancer and many other types of cancer. It can lead to emphysema, and it's bad for your heart.
Smoke makes your blood stickier, raises your "bad" LDL cholesterol, and damages the lining of your blood vessels. Eventually, these changes can make you more likely to have a heart attack or stroke.