'That left law enforcement officials and toxicologists to speculate about what the victims might have inhaled, and how it ended up in the women's room. "We've heard everything from terrorist attacks to carbon monoxide to sewer gas to God knows what else.''
'Pooler Fire Chief G. Wade Simmons said that based on employees' routines at the Pooler McDonald's, workers would have cleaned the women's room early in the day, before serving up Egg McMuffins to the morning breakfast crowd. But the initial report of someone choking didn't get called in until just before noon Wednesday, further deepening the mystery of why people suddenly became ill so much later. None of the products on the cleaning cart had spilled, he said, and the cart wasn't even near the bathroom when patrons began developing symptoms.'
'Dr. Marcel J. Casavant chief of pharmacology/toxicology at Nationwide Children's Hospital in Columbus, said he thought the most likely culprit was hydrogen sulfide, or "sewer gas," which blocks the body's ability to use oxygen. It's called a "rapid-knockdown" gas, he said.'
Georgia McDonald's Toxic Fumes a Deadly Mystery - ABC News
Bit hard to speculate as to the cause of the poor woman's death, until the results of the 80 year old's autopsy's been made public.