Getting to the bottom of the vaping mystery lung illness

It's been a tough week for the vaping industry.

The CEO of Juul, the principal vaping company, stepped down.

U.S. health officials are urging people to avoid e-cigarettes while the CDC investigates 450 cases of lung illness and six deaths that may be linked to chemical exposure while vaping.

The Trump Administration said they will roll out rules banning thousands of e-cigarette flavors soon, as President Trump called vaping "very dangerous."

"We are looking at vaping very strongly," Trump said in the Oval Office earlier in September. "It's very dangerous. Children have died, people have died. ... We're going to have some very strong rules, regulations, and more important, I think we're going to have some very important information come out very shortly. And we'll be reporting that over the next couple of weeks."

Health and Human Services Secretary Alex Azar told FOX Business' Stuart Varney the CDC and FDA are trying to figure out the connection between vaping and the illness.

"Vaping of any substance [is] the public health crisis that the CDC and FDA are fully engaged on, which is trying to get to the bottom [of] why are people getting this mystery lung illness," Azar said on "Varney & Co." 

Azar said they're trying to determine whether it's the products people are using or the oils or the vaping equipment that's significantly harming people's lungs.

Another aspect the FDA is trying to sort out with regards to vaping is the market in general.

"The e-cigarettes that are on the market right now are on the market illegally under the Tobacco Control Act," Azar said. "E-cigarette products have to be approved before marking by the FDA as being in the public health interest. These products have not been."

Azar said the reason the e-cigarettes made it to the market in general even though they aren't approved is that the Trump administration, as well as the Obama administration, exercised what they call "enforcement discretion." What that means is they took a step back and let them get on the market so that cigarette smokers could access the products while the vaping companies prepared their FDA paperwork.

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"But we always said if we find that kids become the users of these products, you're going to have to stop and you're going to have to go through regular order and submit your applications to us in order to be on the market, and that's what we're doing," Azar said.