Scientists Warn Against Breathing in Secondhand Vape 'Smoke' Newsweek Health Problems Caused by Secondhand Smoke Smoking and Tobacco Use CDC Second hand vape smoke linked to more asthma symptoms in kids Think it's just harmless water vapor? Think again. The aerosol from vapes isn't safe not for you and not for anyone around you. What's really in secondhand vape aerosol? About one in four adults in California report being exposed to secondhand smoke or vape in the past two weeksoften on sidewalks, at home, and in recreational spaces like parks and beaches.