A soda fountain is to blame in the death of an 80-year-old woman who was found unconscious last week in a McDonald’s restroom in Georgia, police say. Carbon dioxide, used to carbonate the beverages and normally harmless, was accidentally piped through leaky gas lines in the walls between the soda fountain and the restroom. “At a high level of concentration, it displaces oxygen” needed to breathe, the police chief explains. The woman died by asphyxiation, and nine others were treated as well. The gas lines and valves have since been replaced, the AP reports.