The CDC is now investigating nearly 400 mysterious lung illnesses, related to vaping—calling it an “outbreak.”

So far, 36 states—including Colorado—have reported probable and confirmed cases among adults and teenagers.

“There have been a number of cases, in which young individuals who have no lung disease and no other smoking history, have come in with acute lung injury—in which their lungs are inflamed.”

University of Northern Colorado freshman Piper Johnson is one of those cases.

Her parents say their daughter was hospitalized in Colorado, after developing severe lung illness linked to vaping.

“They have been actively pursued. They have been targeted. They have been wooed by this industry,” Johnson’s mother said, during a press conference earlier this month.

Dr. Joe Forrester, with the Medical Center of Aurora, says the acute lung injury makes it difficult for people to breathe and exhale because the normally paper-like membranes accumulate cells.

“[It’s] almost like when you get a road rash, where you get injury to your skin—it swells up, it gets inflamed. The lungs can have some sort of inflammatory component, so oxygen can’t get in, they get stiffer,” he explained to FOX31.

The CDC says they don’t know the specific cause of the illness, or which product or substance is linked to all these cases.

Dr. Forrester says other studies suggest it’s the flavoring.

“They haven’t identified what flavoring it is, but it appears that the flavoring may have changed the composition within the lung tissue so that there’s more fatty material within the lung tissue,” he told FOX31.

The FDA is also investigating an oil in cannabis products, derived from Vitamin E, and whether it’s linked to these lung illnesses.

“We take it, it’s protective in many circumstances. But apparently, a number of these vaping products have vitamin E in them and Vitamin E as a fat soluble or oil soluble vitamin.”