Los Angeles became the latest city to restrict e-cigarettes after the city council unanimously voted on Tuesday to ban the devices everywhere that conventional cigarettes are prohibited.

Citing their concern over the unknown health effects of e-cigarettes, council members banned them in offices, most public parks and even locales that don't admit anyone under 21. Just about the only place left for e-cigarette users, other than their own homes, will be e-cigarette lounges where patrons go to taste different flavors.

Testimony at the Los Angeles hearing was heated, just as it was in cities such as New York and Chicago when legislators proposed similar restrictions there. People in favor of 'vaping,' as e-cigarette use is known, say it is a useful alternative to regular cigarettes because there is no cancer-causing tobacco. Instead, e-cigarettes heat up cartridges of flavored nicotine juice and users inhale the resulting vapor.

There may be no tobacco, but opponents fear a lack of research on e-cigarettes could mean there are unforeseen health consequences, much like a lack of research on cigarettes half a century ago helped tobacco use become America's number one cause of preventable death.

"We don't want to risk e-cigarettes undermining a half-century of successful tobacco control," said Jonathan Fielding, director of the Los Angeles County Department of Public Health, according to the Los Angeles Times.

Plus, though vaping proponents claim e-cigarettes are a great way for smokers to quit, a study published in The Lancet showed that vapers are only 1.5% more likely to switch to pure nicotine than people who use nicotine patches.

Both sides of the debate are still waiting for the Food and Drug Administration to determine whether e-cigarettes have adverse health effects, and until the organization produces some definitive science, decisions in cities across the country are likely to be fraught with emotionally-charged arguments resulting in varied outcomes.

Thus far, vapers appear to be losing the fight, as New York City, Boston and Chicago have all placed their own big restrictions on vaping in recent months.

When New York City curtailed the use of e-cigarettes, some users feared a domino effect in cities across America. With the addition of Los Angeles, another big domino has fallen.