Is Second-Hand Marijuana Smoke bad for People? \n \n Several years ago, Johns Hopkins University School of Medicine, published a study concluding that secondhand weed smoke can intoxicate nonsmokers under “extreme conditions,” like being in an unventilated room or closed vehicle. \n This is common knowledge for some. But now scientists are starting to look at the health effects of second-hand weed smoke on non-smokers. \n Biologist and professor at the University of California, San Francisco, Dr. Matthew Springer , decided to tackle the issue in that he is already researching the second-hand effects of tobacco. \n So far, Dr. Springer and his colleagues have demonstrated - on rats not humans, not yet because pot is still illegal federally - that secondhand smoke makes it harder for the rats' arteries to expand and allow a healthy flow of blood. \n With tobacco, this effect lasts about 30 minutes before the arteries recover normal function, unless a person is smoking a lot, in which case the arterial walls can become permanently damaged causing all manner of conditions such as blood clots, heart attack or stroke. \n In the case of the stoned rats, the same physiological effect occurred after inhaling secondhand marijuana smoke and their arteries took longer to recover - up to 90 minutes, Dr. Springer recently told NPR . \n Springer concedes that tightly regulated cannabis, free of mold, pesticides and solvents, does not have as many chemical additives as cigarettes. \n But that’s not the point. \n The point is smoke - any smoke, all smoke - is bad for the lungs, heart and blood vessels. \n "People should think of this not as an anti-THC conclusion, but an anti-smoke conclusion," said Springer. \n What about edibles and vaping? \n Caution on the latter, said Springer. Even though vaping doesn't produce smoke from combustion, it does release a cloud of aerosolized chemicals. \n Moral of the story: Be mindful when you toke around non-tokers.