SAN DIEGO -- There is no cure for emphysema but researchers are closer to finding a way to reverse the damage to the lungs.

Johnny Carson's death is making 81-year-old Joe Fairchild take stock on his own life. The former Navy commander has emphysema.

"I was (smoking) three to four packs a day if we were at sea. If we were in port, I was (smoking three packs) for sure," Fairchild said.

He stopped smoking more than 25 years ago but the damage was already done.

"I didn't know what harm I was doing at that time," Fairchild said about smoking.

Emphysema is a condition that causes lung tissue to weaken. Air becomes trapped and makes it difficult to breathe.

"Emphysema is caused by one thing -- cigarette smoking," said Dr. Joe Ramsdell, a pulmonary specialist at UCSD Medical Center.

Ramsdell is working to find a way to slow or reverse emphysema.

One possible treatment is a form of vitamin A. In studies, the compound grew new lung tissue in rodents. Human studies have just been completed.

Ramsdell said, "What the study showed is that it is certainly safe to use in patients with very severe emphysema."

UCSD researchers hope a future study will prove it will regrow lung tissue.

"I do believe in the next five years we'll have an answer as to whether vitamin A or similar compounds are the type of drug that will do it," Ramsdell said.

UCSD is also studying a treatment that could slow down inflammation in the lungs.

Fairchild is thankful doctors are working on finding a cure. He's one of the lucky ones -- he manages his emphysema with daily exercise.

Ramsdell hopes Carson's death will inspire people to stop smoking. He says it's never too late to stop smoking, no matter how old or how long you've smoked.

If you would like more information on emphysema treatments, visit the American Lung Association Web site.