COLUMBUS, Ohio. (KDKA) – When a 31-year-old woman came to the hospital with trouble breathing and coughing, doctors first thought she had pneumonia.

But her condition quickly worsened, and she ended up in the ICU. Tests for infection didn’t turn up anything. Doctors were stumped.

And then, they figured it out: she was exposed to e-cigarettes.

That was in 2015.

Doctors published her case as one of the first documented instances of lung injury related to e-cigarettes.

“After one or two months afterwards, on the follow up, she had complete resolution.”

But last year, when there was an explosion of similar cases across the country, researchers went into overdrive.

“You’ve got a national emergency, literally with people ending up on respirators, in ICUs, intensive care units, and some dying, what’s going on with that?” said Dr. Peter Shields, Ohio State University lung cancer specialist.

“What’s the long term effects of the e-cigs, which may be separate? And how does that balance out with the numbers of people who may be able to quit? And there’s the kids, and the flavors?”

Researchers everywhere have been trying to tackle each of those questions. At Ohio State, they’re taking them one at a time.

For starters, they looked just at the e-cigarette additives — propylene glycol and glycerin. The FDA says the compounds are safe for eating or putting on the skin, but what does it do to the lungs?

Researchers asked 30 healthy people, in their 20s, who have never smoked to participate.

They learned to use e-cigarettes, and for a month, they vaped propylene glycol and glycerin only — no nicotine, no flavors. The doctors then took samples of their lung tissue.

“For things like inflammation, gene expression, looking for toxic effects,” says Dr. Shields.

And they did the same thing with a group of nonsmokers.

At the Ohio State University cancer center, the study samples from the bronchoscopies go to a lab to be processed. The researchers measure chemicals the body makes that go up during inflammation, and count certain immune system cells that also go up with inflammation.

To make sure the test subjects truly inhaled, propylene glycol was measured in the urine.

In people whose propylene glycol levels went up with the e-cigarettes, there was an increase in inflammation.

“So it was measurable, but not necessarily clinically significant,” says Dr. Shields.

Even so, because there was any increase at all, Dr. Shields says: “One should not make the claim that these are safe.”

He admits the damage is less than what you’d see with regular cigarettes but cautions:

“Maybe they are safer than cigarettes, but that’s not the same as safe. And then it’s how safe?”

And he says the most recent cases of lung injury are a different problem all together — not related to propylene glycol and glycerin, but possibly due to other components such as oils causing a different reaction in the lungs.

“Now we realize we need to be looking at other things, like the lipids we’re seeing in the vaping related illnesses,” says Dr. Shields.

“We barely know what these people are using. We know that something changed this year.”

For months now, the CDC and FDA have recommended not using e-cigarettes, and they say they’ll continue to do so until researchers can explain some of the unknowns.

Dr. Maria Simbra