Late today San Francisco became first major American city to approve a ban on the sale of electronic cigarettes. The crackdown is aimed at reducing teen vaping. One in five American high schoolers admitted to vaping last Y Jamie yuccas is in San Francisco. Reporter: The city-wide ban on e-cigarettes and popular vaping flavors will cause smokeshop profits to go up in smoke. It would be 30% to 40% of your business if this all went away? Yeah, I’ll say about 30% to 40%, because everybody is on vape nowa-days. Reporter: Farah says he sells only to adult, but increased use by teens overall has reached troubling levels. The centers for disease control found a 78% surge in the use of e-cigarettes by high schooler from a single year from 2017 to 2018. They were allowed to proliferate all over this country with no regulation, and hire we are today now with millions of addicted children, teenagers. Reporter: With a 70% share of the vaping market. Juul is the largest manufacture of e-cigarettes. What would you say is the most popular one? Juul. Reporter: This it? Yes. Reporter: The company did not respond to our request for an interview, but they claim they’re safeguarding social media. When you go to Twitter — You must be 21 plus to follow. But when you click on it, I don’t have to enter my birthday or do anything. That’s what we would want for tobacco product, something that’s very stringent, not just, I’m over 18, click yes, I’m in. Reporter: The ban will take effect in sever months, giving stores time to clear their Jamie yuccas, CBS news, San Francisco.