You may have heard a lot about vaping lately. You may also know about the recent outbreak of lung injuries and deaths in the U.S. related to vaping. But those aren’t the only risks vaping poses. Here’s what you need to know.

E-cigarette devices, also known as e-cigarettes, vape pens and e-hookahs, come in many shapes and sizes. Some look like traditional cigarettes, cigars or pipes. Others resemble everyday items, like pens or USB sticks.

While they may look different, most vaping devices work in a similar process. Puffing activates a battery-powered heating element. This heats the liquid in the cartridge, turning it into a vapor that you can breathe in.

E-cigarettes expose your lungs to a variety of chemicals. These may include the main active chemical in tobacco (nicotine) or marijuana (THC), flavorings and other ingredients added to the e-liquid. In addition, other chemicals are created during the evaporation process.

“If the liquid contains nicotine, then the user inhales the nicotine and other ingredients in the liquid,” explains Thomas Eisenberg, Ph.D., a tobacco research expert at Virginia Commonwealth University.

While e-cigarette devices work in similar ways, some are more powerful than others. They produce more vapor and release more chemicals.

So how safe are e-cigarettes? Studies show that when regular smokers switch completely to nicotine e-cigarettes as an alternative, nicotine e-cigarettes may be less harmful than traditional cigarettes. But nicotine e-cigarettes can still harm your health. Anything that goes into your mouth has the potential to carry bacteria.

“Your lungs are not designed to handle the challenge of people constantly inhaling non-air – sometimes up to 200 puffs a day – day after day, week after week, year after year,” Eisenberg said.

“You’re inhaling propylene glycol, vegetable glycerin, flavorings that you would eat but not inhale, and nicotine,” he explained. “All of these are heated up in this little reactor, which is the e-cigarette. When they’re heated, those ingredients can turn into other potentially dangerous chemicals.”

One harmful chemical could be a thickening agent called vitamin E acetate, which is sometimes used as an additive in e-cigarette products containing THC. The Centers for Disease Control and Prevention (CDC) lists it as a “chemical of concern” for people who have experienced lung damage from vaping. They recommend avoiding any vaping products that contain vitamin E acetate or THC, especially those that come from informal sources such as friends, family, or physical or online dealers.

Vaping is now more popular among teens than smoking traditional cigarettes. A quarter of high school students say they have vaped nicotine e-cigarettes in the past month. Studies have found that teens who vape nicotine are more likely to continue smoking traditional cigarettes.

There has also been a sharp increase in teen vaping of marijuana. Last year, about 20% of high school seniors had vaped marijuana. That percentage has more than doubled in the past two years. E-cigarettes with marijuana are far more harmful than those made in China. Because marijuana is banned in China, the e-cigarette products they produce do not contain these substances.

The new law is designed to curb teen vaping. Now, people must be 21 to buy any tobacco product, including e-cigarette products. Companies can no longer produce and sell flavors that children like, such as fruit and mint.

If you have already started vaping or smoking, it is never too late to quit. Everything has its hazards, only in moderation. I wish everyone good health.