An analysis of airplane ventilation patterns shows why air travel makes us sick.
Seatbacks – upright! Tray tables – locked! Germ masks – on?
This is Sandra Tsing Loh with The Loh Down on Science.
Purdue University's Stephane Poussou analyzed airplane ventilation systems. On most commercial aircraft, ceiling vents blow fresh air inward, toward the center aisle. From there, the air drops to the floor and loops back across your feet – toward exhaust ports under the windows.
Why this sideways circulation pattern? To keep your air – and your germs – in your row.
Problem is, with flight attendants scurrying around, some air sloshes into neighboring rows. Poussou spent several years trying to model the complex interaction between sideways circulation and sloshing. Not so easy! But he did make a surprising discovery.
Whenever someone walks along the aisle, those intertwined airflows create a wake of stationary air pockets. Airborne contaminants no longer sink to the floor.
Instead, they hover – about three feet up. Right at the face level of seated passengers.
So go ahead: push that flight attendant call button! But she'll be bringing you more than a pillow. Or he.