In Alabama, a school removed the doors from bathroom stalls to stop students from sneaking inside to vape. And in Pennsylvania, a school has tried installing sensors to detect vaping in bathrooms and locker rooms. At least 530 people have been sickened by lung illnesses related to using e-cigarettes or vaping THC, the psychoactive ingredient in marijuana. At least eight have died. That has sent high schools racing to give teenagers an urgent message: Vaping can be deadly.