Truth Initiative Secondhand smoke is classified as a Group A carcinogen, a substance known to cause #cancer in humans and animals. Learn more at the link in Instagram Avoiding Tobacco Smoke and E Cigarette Aerosol Is a Key Part of Asthma Management Asthma and Allergy Foundation of America Secondhand Smoke and Electronic Cigarette Aerosols US EPA Sitting somewhere when a cloud of cotton candy vapor washes over you? If you can smell the sweet scent of a vape, that's not a great sign.