can you legally smoke cigarettes at 16 TIL U.S. States Still Allow Smoking Inside Bars and Restaurants : r/todayilearned Legal smoking age - Wikipedia

Yousey, Y K (2006), Household Characteristics, Smoking Bans and Passive Smoke Exposure in Children, Journal of Pediatric Health Care 20(2): 98-105.

Man Wong, a graduate student and first author of the paper, said one particularly concerning finding is that lower-powered e-cigarette devices, often assumed to be safer, might produce higher levels of methylglyoxal

That means the cabin crew can't check them for issues, which could lead to severe risks

They may work and look similar to electronic nicotine delivery systems or electronic cigarettes (particularly vape pens) but they have been officially approved by authorities all over the world to be used as a tool for quitting smoking