Over the next few years, the optimism over smoking e-cigarettes waned as their popularity skyrocketed. Juul’s sales increased over 600 percent each year to become the best selling device on the market while I inhaled an atmosphere’s worth of vanilla vapor into my lungs. I never kidded myself into thinking that this habit was harmless, but my conviction that they were less harmful than cigarettes made the endeavor seem worthwhile, even praiseworthy.

After all, the average cigarette has some 4,000 chemical compounds, including dozens of confirmed carcinogens, while my e-cig cartridges contained just five: distilled water, nicotine, glycerin, propylene glycol, and some flavoring.That’s a flimsy argument: “something with lots of scary chemicals is less dangerous than something with just a few scary chemicals.

Firstly that propylene glycol, largely responsible for making your breath look like a cloud of mist, is also found in fog machines used in concerts and has been linked to chronic lung problems among stagehands. It’s actually FDA-approved for use in food (believe it or not it’s common in pre-made cake mix) but when heated to vaping temperature it can produce the carcinogen formaldehyde.

In other words, just because something is safe to eat doesn’t mean it’s safe to be inhaled. (Duh.) Vaping also seems to trigger potentially harmful immune responses in the lungs. It’s not just tasty air.

“As time passes, the evidence that these are a lot more dangerous than people thought keeps piling up,” says Dr. Stanton Glantz, Director of UCSF’s Center for Tobacco Research, Control & Education. “In one disease they seem worse than cigarettes: they seem to turn on more inflammatory and depressed immune function in lungs than cigarettes. And evidence the effects on the cardiovascular system approach that of a cigarette is also piling up.”

Indeed, the vapor may have a lot more than those five ingredients listed above. Some studies have found it to contain lead, nickel, tin, and silver from the machinery inside the devices along with formaldehyde, manganese, tolulene, and other ingredients linked to cancer, central nervous system problems, and other possible health issues. A 2018 study of e-cig smokers’ urine found at least five of the same carcinogens found in cigarettes.

It had become apparent that there were problems with my vape-saves-the-day habit.