Smoking can cause heart attacks and strokes. Many smokers don’t know that

Smoking cigarettes doesn't just cause lung cancer . The toxic smoke affects nearly every organ in the body — yet some of its most serious consequences may be less widely recognized.

Smoking is a major cause of cardiovascular disease, including heart attacks and strokes, and exposure to secondhand smoke puts people who don't smoke at risk, too.

A recent study published in the journal BMJ Open found major gaps in how well people who smoke understand these risks. While more than 9 in 10 people surveyed across 46 countries knew that smoking causes lung cancer, substantially fewer knew of its cardiovascular effects. Awareness of the cardiovascular dangers of secondhand smoke was even lower.

Why does smoking have such profound effects on the heart and blood vessels? How dangerous is secondhand smoke, and what should people who smoke and those around them know?