Secondhand smoke is defined as the mixture of the smoke breathed out by the smoker combined with the smoldering end of a cigarette, cigar or pipe. According to the United States National Library of Medicine, secondhand smoke contains more than 7,000 chemicals, 70 of which are known to cause cancer and hundreds more are toxic.

Even a low dose of secondhand smoke can contribute to sudden infant death and cause ear infections and asthma attacks in children while causing cancer and heart disease in adults.

Secondhand smoke kills one person for every 52 smokers, study says. That's a million people worldwide each year