Millions of people are exposed to secondhand smoke every day. People living in multi unit housing are some of the most exposed. The only way to fully protect people from secondhand smoke at The risks of vape pens' secondhand aerosols Juul study shows secondhand vaping emissions are less toxic than cigarette smoke Secondhand Smoke and Secondhand Vaping: Both Bad for Kids University Hospitals Secondhand vape plumes could form lung damaging radicals American Chemical Society Health: In secondhand vape, scientists smell risk Journal Courier