The city of San Antonio recently extended its prohibition on smoking to Main Plaza and Travis Park — two public spaces downtown that often garner crowds.

And in October, a state law took effect that prohibits the sale of e-cigarettes to minors and the possession of the devices by minors.

But you can still legally use e-cigarettes in the places where smoking is otherwise banned.

That’s likely not to always be the case. The city is waiting to see whether the Food and Drug Administration creates a new rule that would put e-cigarettes, vaporizers and other noncombustible smoking devices into the same category as old-school cigarettes. If that happens, the new generation of smoking will be relegated to the decks and back porches smokers flood to now.

Currently, the FDA doesn’t regulate the everyday use of e-cigarettes, which don’t have tobacco. The devices use liquid nicotine cartridges, often flavored, to create a vapor that’s inhaled.

Until the FDA changes how the devices are categorized, San Antonio appears to be in a holding pattern. Mayor Ivy Taylor said there isn’t any discussion planned on e-cigarettes this year.

“We are researching the FDA’s timeline on addressing this, too,” she said.

Whether the FDA takes action — and how quickly — remains to be seen. A spokesman for the federal agency said it received some 135,000 comments on the proposed rule. The FDA has since submitted the proposal to the Office of Management and Budget, which conducts its own review. Other agencies also have opportunities to weigh in on the matter, the spokesman said.

Dr. Vincent Nathan, interim director of the city’s Metropolitan Health District, said the intent is for the city ultimately to ban e-cigarettes from use in the places where smoking is prohibited. In San Antonio, the list is long. It includes restaurants and bars, public- and private-sector workplaces, the San Antonio Zoo, sporting facilities and amphitheaters, among other places.

Nathan said the city doesn’t want to be in a position where it’s amending its ordinance every time a new product hits the shelves. But it’s well within the city’s right to ban the use of e-cigarettes, as it has smoking, he said.

“We certainly can put an e-cigarette ban in. If the feds don’t move on this by the end of the year, we may do that,” he said, adding that “it is our intent” to prohibit vaporizers and e-cigarettes.

Councilman Rey Saldaña said the amount of time it could take the FDA to act on the matter is worrisome. If science shows that secondhand vapor causes health concerns for others, or if there’s substantial public outcry, Saldaña said, he’d be comfortable acting before the FDA resolves the matter.

But part of the problem is that because the FDA doesn’t regulate the devices, it’s hard to know exactly what’s in the vapor cartridges, besides nicotine, Nathan said. The vapor is clearly a “lung irritant,” he said.

“Whether it’s a carcinogen, we don’t know,” he said.

The vapor cartridges are typically flavored — from gumballs to dulce de leche — and their ingredient lists aren’t clear.

“We don’t really know what all of those flavors are,” Nathan said.

Stanton Glantz, a professor of medicine at the University of California, San Francisco and director of the Center for Tobacco Control Research and Education, noted in a 2013 blog post at tobacco.ucsf.edu that nine compounds identified in mainstream or secondhand e-cigarette vapor are on California’s “Prop 65” list of known carcinogens — including formaldehyde and lead.

Councilman Cris Medina, who had advocated for a local ban on selling e-cigarettes to minors more than a year before the state law took effect, said the city is in a holding pattern and that there needs to be community input before a ban would be implemented, absent an FDA decision.

“Anything we can do to protect the public health,” he said, “is important to me.”