The world's most beloved "blue man" passed away Monday.

Paul Karason, 62, was hospitalized after suffering a heart attack about a week ago, NBC's Today reported.

The cause of death was not immediately known, but the man also had been struggling with pneumonia and had suffered a severe stroke, his estranged wife, Jo Anna Karason, told Today. Karason was also a heavy smoker, and kept up the habit even after undergoing triple-bypass surgery five years ago.

"He has been too ill to work for a while," Jo Anna said, adding that he had spent the past few years watching the History Channel and reading.

"He didn't like to go out in public much -- only when he thought he needed to, like to go to the bank or to pick up tobacco," she told Today.

Mr. Karason first started to notice that he was turning blue 15 years ago when a friend came to visit him ABC News reported.

"And he looks at me and he says, 'What have you got on your face?' 'I don't have anything on my face!'" Karason said, ABC reported. "He says, 'Well, it looks like you've got camouflage makeup on or something.' And by golly, he came in and he was very fair-skinned, as I used to be. And that's when it hit me.

The cause of Karason's condition was believed to be colloidal silver. He drank a 10-ounce solution of the substance daily to treat a case of dermatitis after seeing the treatment advertised in a new-age magazine.

Silver solutions were once the norm for treating infections, but went out of style after penicillin was invented in the 1930s. It was banned in over-the-counter medicines in 1999 because it causes argyria, the condition Karason suffered from, Today reported. The rare condition occurs when silver collects in the organs and reacts to light in the same way it would in a photograph.

Karason was often called "Papa Smurf" because of his blue-tinted skin and brilliant white hair.

"That was a nickname he didn't appreciate, depending on who said it," Jo Anns told Today. "If it was a kid who ran up to him saying 'Papa Smurf,' it would put a smile on his face. But if it was an adult, well ...."

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