On Tuesday night, San Francisco’s Board of Supervisors instituted a ban on e-cigarette sales, making it the first U.S. city to outlaw the vaping industry.

Sales of e-cigarettes have skyrocketed over the past decade, ever since marketers began promoting vaping as a healthier alternative than traditional smoking. However, the latest research shows that these products are still hazardous.

“The long-term health effects of e-cigarettes are not well understood yet,” an official statement from the American Heart Association reads. “But the science suggests vaping is not a safe or healthy alternative to smoking conventional cigarettes.”

Experts warn that the use of e-cigarettes can lead to popcorn lung—an irreversible condition that causes breathing difficulties. A growing number of vape pen explosions have also caused authorities to warn users about the risks of bodily injury.

“San Francisco’s lawmakers have done what the FDA should have done years ago: ensure that e-cigarettes undergo the appropriate health review before hitting the shelves,” said Matt Wellington, campaign director of the U.S. Public Interest Research Group. “With the rampant rise in e-cig use among our kids, it’s clear the agency made a bad call by letting e-cigarettes remain on the market.”

But not everyone agrees that banning e-cigarettes is the proper solution. Ted Kwong, spokesman for leading e-cigarette manufacturer Juul, warns that outlawing these products will only cause users to resort to traditional smoking methods.

Juul is currently facing multiple lawsuits for allegedly marketing its products to underage users. The company denies these allegations.

“This full prohibition will drive former adults smokers who successfully switched to vapor products back to deadly cigarettes, deny the opportunity to switch for current adult smokers and create a thriving black market instead of addressing the actual causes of underage access and use,” said Kwong.

The ban will go into effect Jan. 1 and will remain intact until the FDA investigates the safety of e-cigarettes.