From a linked article:<p>> The exchange rate of air in the cabin is higher than most other environments, like our home, office, or most other public spaces. “There are between 12 to15 air changes in an hour and 25 to 30 cycles through a HEPA filter,” he said.<p>I guess I never thought about cabin air that much, this explains why no one gets C02 poisoning on a 14 hour flight.