LACONIA — A 57-year-old man suffered third-degree burns after he fell asleep while using medical oxygen and smoking, igniting a fire in his Jameson Street apartment.

Laconia Fire Department Capt. Bob Landry said the man, who depends on a home oxygen tank because of medical problems, “fell asleep with a cigarette in his hand.”

The man’s lit cigarette ignited the oxygen, he said. “He woke up and he was on fire.”

When firefighters arrived, the man, clad only in his underwear, was standing in the doorway of his apartment “with fire lapping all around him.”

The man uses a wheelchair but managed to “hobble” to the front steps, Landry said. “All he could do was stand, holding onto a beam.”

The man was taken by ambulance to Lakes Region General Hospital and then flown by DART helicopter to a Boston hospital, Landry said. The man suffered burns to his face, arms, hands and the right side of his body and was in serious condition, Landry said.

“He has probably 40 percent of his body burned, a good portion of it third-degree,” he said.

Landry would not release the man’s identity, citing patient confidentiality laws.

The fire followed the oxygen tubing across the apartment, Landry said, “burning its way through the rug, and then it got to the oxygen machine itself and set that on fire.”

Landry said oxygen can saturate the user’s hair and clothing. When a lit cigarette comes in contact with the oxygen, he said, “all that immediately goes up in flames, and you end up with facial burns.”

Landry said the building’s sprinklers were working and fire damage was confined to the one apartment. Three other units in the same building are vacant.

The captain said it’s the third fire involving smoking and medical oxygen that he’s seen in recent years.

A recent report by the state Fire Marshal’s Office found that smoking materials were the leading cause of residential fire fatalities from 2005 to 2010, responsible for 1 in 4 deaths. And it found 8 percent of the victims were smoking while using medical oxygen.