Dr. Chung, we know that some of the cabin air in an aircraft is recirculated after it's been filtered, so I'm hoping you can elaborate on the ventilation system in the aircraft.
First, how does the ventilation system in an aircraft work when the aircraft is in the air? Can you elaborate on the flow pattern of the air in the aircraft and whether it is more likely to contribute to the spread or whether it is effective in preventing the spread? Is there something that the passengers can do to help the ventilation system, such as perhaps keeping the vents above their seats off? Also, how does this differ when the aircraft is parked and the engines are off in the case of ground delays?