Police had conducted a well-being check Monday evening, as the couple hadn't been heard from in three weeks.
Police Lt. Dale Kingsley said their Grand Crossing neighborhood home was "packed from floor to ceiling" with garbage.
Officials said the couple - a 79-year-old woman and a 76-year-old man - appear to be hoarders. Junk was stacked from the floor to the ceiling in the basement and first and second floors.
Paramedics found the stench so overpowering they had to don hazardous materials suits before going inside the home, according to Fire Department spokesman Kevin MacGregor.
The couple, possibly suffering from malnutrition, were taken to Jackson Park Hospital and Medical Center in critical condition, according to Kingsley. were taken to Jackson Park Hospital.
By Tuesday morning their condition had improved, according to a hospital nurse.
Foul play is not suspected, according to Kingsley, who said the building will likely have to be condemned.
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