Before the risks of second-hand cigarette smoke were better understood and led to laws that curtailed smoking in public places, it was common to hear a polite tobacco user ask: “Mind if I smoke?”

Comedian Steve Martin had a snappy comeback that we won’t repeat here — kids, ask your parents — but which might again be useful with the growth in the use of e-cigarettes.

E-cigarettes are battery-powered, typically cylindrical devices that heat a small amount of flavored liquid, commonly containing nicotine, into an aerosol vapor that is inhaled like tobacco smoke, resulting in a pretty impressive cloud when exhaled.

Users of e-cigarettes and the vaping industry defend the devices as a substitute for tobacco and as a way for many to quit smoking. According to a recent study by the Centers for Disease Control and Prevention, about 12.6 percent of all adults and 21.6 percent of young adults 18 to 24 have tried vaping at least once, but only 3.7 percent currently use e-cigarettes every day or on some days. The same study also found that current tobacco smokers and those who had quit smoking within the past year were more likely to use e-cigarettes than former smokers or adults who had never smoked.

There’s conflicting information on the safety of e-cigarettes. A review of evidence published by Public Health England, the United Kingdom’s public health agency, found that vaping is significantly less harmful than smoking because the carcinogens and other unhealthful components of cigarette smoke aren’t present in e-cigarettes.

But the vaping liquid often does contain nicotine, which is an addictive drug. And the liquid used isn’t regulated by the federal Food and Drug Administration. There is no standard for the ingredients in the liquid, and often ingredients aren’t listed beyond a general description of the flavors. While anecdotal, there also have been reports of vaping devices exploding and causing fires.

Were this simply a matter of personal risk, it would be up to individual users to determine whether this was a safe choice for themselves. But just as we have passed laws that address second-hand smoke, until more is known about what’s exhaled into the air we all breathe and what the risks are for others, specifically pregnant women, children and those with compromised lungs, we need to place the same restrictions on public vaping that we do on public smoking.

The Snohomish Health District’s Board of Health on Tuesday, will hold a final public hearing and could vote to adopt changes to the county’s sanitary code that would consider vaping in public similar to smoking:

• The use of e-cigarettes would be prohibited in public places, including restaurants and bars, and in places of employment.

• E-cigarette products couldn’t be sold to or possessed by minors.

• Sales would require photo ID and the products would have to be kept behind a counter in a secured display.

The proposal would make an exception that would allow some of the shops selling e-cigarette products to offer sampling of the vaping devices and liquid.

The Snohomish Health District has not rushed the process. Three months ago, district staff, led by Director and Health Office Gary Goldbaum, began seeking public comment on the proposal and specifically sought out the opinions of shop owners and those who use the products. The exception for sampling was a result of that process.

Goldbaum isn’t arguing with those who see these as life-saving devices and as a way to stop smoking.

But he does have concerns for what we don’t know about the contents of the liquid and about the use of vaping products by youths. The state Department of Health’s 2014 Healthy Youth Survey found that nearly 1 in 4 high school seniors had used e-cigarettes in the past 30 days, raising the likelihood of nicotine addiction. The flavored liquid also can also pose a risk of poisoning if ingested by children.

“Safer doesn’t mean safe,” Goldbaum said.

E-cigarettes have been around for about 10 years, and we’re just now learning more about their potential benefits and risks to health. Some restrictions regarding their use in public are reasonable and necessary.