MANHASSET, N.Y. (CBSNewYork) — The dangers of vaping have been all over the news of late.

On Thursday, a Long Island man spoke out about nearly dying from it.

The Roslyn Heights resident told CBSN New York’s Cindy Hsu he’s lucky to be alive.

“I can’t express how much that that basically almost killed me. I thought it was just relaxing me, and it wasn’t. It was killing me,” Jonathan Doneson said at North Shore University Hospital.

MORE: Vaping Facts Versus Fiction: Nicotine, THC And The New Mystery Illness

The 52-year-old was talking about vaping THC, which is the chemical in marijuana that gets you high. He said he had been vaping from a pen every day for several weeks for several months to relieve stress, but then started to feel sick.

“Coughing, your lungs feeling tight, sweats, loss of appetite,” Doneson said, describing his symptoms.

MORE: N.J. Lawmaker Wants To Ban Sale Of All Vaping Products; FDA Eyes Flavored E-Cigarettes

Doctors said he was treated for bronchitis, but the symptoms continued. When they learned he had been vaping THC, they found lung damage and realized he also had double pneumonia.

They treated him with steroids and antibiotics, and he eventually recovered.

His doctors are concerned about the ingredients being vaped.

“We don’t know what’s inside them. A lot of them are counterfeit products. They do have marijuana in them, but they have other things that we don’t know, like pesticides, carcinogens, cancer causing agents,” pulmonologist Dr. Mina Makaryus said.

Doneson wouldn’t say where he bought his THC, but after he got sick, he had it tested. What did they find?

“Formaldehyde, pesticide, vitamin E and a little dab of THC,” he said.

He’s really concerned about kids in middle and high school.

“It alsmose killed me. So don’t be the big shot who thinks, ‘Oh, I got the THC pen,’ and you want to show off to all of your friends, ‘look I got the new one.’ It’s not cool,” he said.

His doctors are warning everyone to stop vaping, whether it’s nicotine or marijuana.

“We don’t know what the long-term affects are of these substances they they are using. We don’t know if they’re going to cause cancer in 20-30 years from now,” Dr. Makaryus said.

Currently, the Centers for Disease Control is investigating hundreds of cases of illnesses believed to be related to vaping, and so far six people have died.