Lynda Baquero, NBC New York:
Americans are smoking less.
Just this week, U.S. tobacco companies released first quarter earnings that showed cigarette sales were down from last year.
But smoke-free products like e-cigarettes are growing in popularity, and are marketed as a less harmful alternative.
And some health advocates are raising alarm bells.
One woman says she experienced an adverse health issue after making the switch.
Patricia Nixon switched from regular cigarettes to e-cigarettes about three years ago, mainly because of the price difference.
"It made sense to make the switch especially if it's supposed to be a healthier choice," Nixon says. "It seemed like a win-win, cheaper and healthier."
But is it really healthier?
Patricia says she's noticed a difference.
"I feel bad to admit, I do have asthma and rarely, I mean I throw an inhaler in my pocketbook when I am jogging or running," Nixon says.
After recently switching to a particular vapor flavor, Patricia says she's become much more dependent on her inhaler.
"I was using it constantly to where opposed to an inhaler with two hundred puffs lasting a year, now it was lasting less than two months," Nixon says. "My breathing, it felt like my chest was being glued shut, literally."
The makers of the vapor flavor, Johnson Creek Enterprises, say they advised Patricia to stop e-smoking and consult her doctor.
They also tell us there are warnings on their website discouraging e-smoking for anyone with asthma and other medical conditions.
Dr. Byron Thomashow is a clinical professor of medicine. He's also medical director of the center for chest disease.
"All of these agents might potentially have adverse effects upon the airways, that's why you need to study them," Dr. Thomashow says.
Dr. Thomashow says a base ingredient in e-cigarettes is nicotine, which he described as an extremely addictive substance.
An industry group -- The Tobacco Vapor Electronic Cigarette Association -- says it's been performing laboratory and clinical studies on the safety of electronic cigarettes over the past two years.
The FDA released a statement regarding its stance on e-cigarettes.
"FDA intends to propose a regulation that would extend the agency's ‘tobacco product' authorities to other categories of tobacco products.
Further research is needed to assess the potential public health benefits and risks of electronic cigarettes."
"I think that anything that has potential harm should be regulated, I do," Dr. Thomashow says.
"I do think they need to monitor or look at this because I don't know what's going on," Nixon adds.
The FDA says it plans to release its proposed rule for regulating additional tobacco products very soon.