HEPA filtration while planes are on the ground

[pizzaman]

Southwest says "Each aircraft is equipped with a sophisticated air distribution system that introduces fresh, outdoor air and HEPA filtered air into the cabin every second while inflight, resulting in exchange of cabin air every two to three minutes.", which says the HEPA filters are working great in flight, but they don't detail what's happening on the ground.

If I have an itinerary that calls for a no-plane-change layover, are the HEPA filters still exchanging the cabin air every two to three minutes while the plane is on the ground for deplaning, cleaning and boarding?

This article from a year ago implies that Southwest isn't running the HEPA filters at 2-3 min recirculating intervals while on the ground, but it's a year old and not very clear.

Would love some guidance on what air filtration looks like while the plane is on the ground in between flights, thanks!

[dfwskier]

Planes don't use different airflow systems on the ground vs in the air. Thus air filtration is the same in both cases. The air comes in via engine bleed while the plane is in the air and via a truck mounted "blower" when the plane is on the ground.

Air enters the aircraft via ducts near the ceiling and exit the aircraft via vents near floor.

[pizzaman]

Thanks. Is the "blower" on at full strength the entire time the plane is on the ground?

[TheMiddleSeat]

Depends on a variety of factors that cannot be predicted including the unit used and if the airflow is restricted by a crimp in the flexible tube running to the aircraft. I've seen them fully blocked off and I've also experienced crazy high airflow.

--TheMiddleSeat