This week London Breed, San Francisco's mayor, will sign legislation making the city the first in American to ban the sale of e-cigarettes.
Shops will be prohibited from stocking vaporisers and vaping fluid, and online vape store from delivering to local addresses.
Health officials argue that e-smoking's effect are unclear. But even if vaping is not risk-free, it is almost certainly much safer than inhaling cigarette smoke. Quitting tobacco is not easy, while many find vaping an effective way of giving up.
