And there are other reasons. "After investigation and observation, I've learned that these people have [tracheotomies]; they have infections, they have a lot more problems," Mason said. "I don't know of any one of them who has used that equipment for 60 years and had a good life with it."
And Dalton, the filmmaker, said there is another reason Mason chooses to stay in her iron lung -- independence.
"The thing I think is so interesting about Martha's life is that she chooses to live in an iron lung because she can be independent that way," she said, adding that the lung needs no monitoring by a medical professional, and it allows Mason to remain in her own home, surrounded by the people and things of her choosing.
"Because she is living in that community, her life is so rich and so full, and she is autonomous," Dalton said. "Her iron lung is not invasive. She doesn't have any tubes anywhere; it's her in the iron lung."
And while the degree of freedom afforded by the lung is limited, Mason noted that she has done her best to make the most of her situation. Thanks to an intercom system, she was able to attend Wake Forest College -- what is now Wake Forest University -- from 1958 to 1960. During her graduation, she made a brief foray out of the iron lung to accept her degree.
And this past spring, she and her classmates celebrated the 50th anniversary of their intake. This time, a computer monitor and Webcam allowed her to be part of her class in a way she never was before.
"It was set up so my computer monitor was even at the banquet," she said. "Of course, they all called and talked to me. ... I had all of these people and faces."
Unlike Odell's iron lung, Mason's is backed up by a fully functioning emergency generator. She said that in addition to the backup generator, the fire department sends a crew to her house whenever there is a power outage, just to make sure her iron lung is functioning properly. "The firemen have been wonderful," she said. "They're prompt; they're always here immediately."
These are benefits she said Odell likely did not have. And in past telephone conversations with Odell, she said she knew the Tennessee woman endured a far worse situation than she has encountered.
"She called me one day, and her sister called me a couple of times before," Mason said. "I don't think she was very well. … It makes me give some thought to how fortunate I am."
And as one of the few surviving people left who live their lives encased in an iron tank, she said she intends to continue as she always has -- making the most out of what life has offered her.
"Get as much joy from life for yourself and others as you can squeeze out of it," she said.
Lara Salahi contributed to this report.