If you were an adult in the mid-1960s, there is a good chance that you or one of your family members smoked cigarettes. More than 40 percent of adults smoked during that time, and that number shrank to 13.7 percent in 2018, according to the Centers for Disease Control and Prevention (CDC).

While the decline in cigarette smoking gives health advocates a reason to cheer, experts are concerned about an alternative taking its place: vaping.

The smoking substitute is steadily becoming more popular, and studies show that those taking up the habit are getting younger.

Many wonder whether vaping is on the list of heart disease causes, and they're questioning whether the practice is safe.

Basics of E-cigarettes

For starters, most e-cigarettes work by battery and heating element that holds liquid containing nicotine. That liquid is usually infused with some sort of flavor such as peach, banana or lime. When vaping, users inhale an aerosol vapor.

So who is vaping? E-cigs are found more often in the hands of young people. Over the past several years, e-cigarettes were the most commonly used tobacco product by youth. In fact, more than 2 million middle and high school students were current users of e-cigarettes in 2017.

That trend among teens has reached an "epidemic," according to the Food and Drug Administration.

Approximately 60 percent of the adults who vaped were also smoking regular cigarettes, and approximately 30 percent had since quit smoking. However, almost half of young e-cigarette users, those aged 18 to 24, had never regularly smoked traditional cigarettes.

Another Cause of Heart Disease?

There are many heart disease causes. Could vaping be one of them? Scientists are looking into it.

So far, researchers have found that vaping is less toxic and generally safer than traditional cigarettes, according to 2017 data published in The Annals of Internal Medicine. This is because using e-cigarettes, when not used in combination with regular cigarettes, produce a significantly lower level of carcinogens and chemicals than do traditional tobacco cigarettes, the study found.

But that doesn't mean they're safe. A recent UCLA study shows that those who use e-cigarettes are more likely to have symptoms of oxidative stress and elevated adrenaline levels in the heart, two primary risk factors for heart disease, than non-users.

And smoking e-cigarettes while also smoking traditional cigarettes could mean even bigger trouble for your heart.

Stanton Glantz, Ph.D., director of the University of California, San Francisco Center for Tobacco Control Research and Education, said that many people perceive vaping to be a good smoking cessation aid. But using e-cigarettes, Glantz found in a recent study, actually made it harder to quit smoking, and most users he surveyed ended up using both products.

And doing so could seriously endanger the heart: When traditional and e-cigarettes were used together, users' risk of heart attack increased by 600 percent, Glantz found.

Health experts say more long-term research about vaping is needed to reach concrete conclusions about e-cigs and whether they ultimately improve heart health. If you're unsure whether you should consider vaping, current research suggests you shouldn't. Either way, be sure to talk with your doctor about the health risks.