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Plane HEPA air filters

New Arrival

As a physician, it seems to be not well understood that HEPA air filters, as used in plane air systems, are only able to effectively filter out particles larger than 300 nm (0.3 microns). The HEPA virus particle is between 70 and 120 nm in size (0.07-.12 microns), and therefore would not be fully filtered by a HEPA filter. That said, the transmission of Corona virus is mostly by droplet exposure from someone coughing or sneezing within six feet of your location, or by touching a contaminated surface and then touching your nose, mouth or eyes. Such droplets would be fully filtered by a plane's air handling system. Also, only about 20% of cabin air is recirculated - the rest is brought in fresh from outside the plane and discharged out of the plane at a fairly rapid rate. Thus, the chances of Corona virus infection from recirculated air is still exceedingly low.

7 REPLIES 7
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Re: Plane HEPA air filters

Top Contributor

Thanks for your insight.

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Re: Plane HEPA air filters

New Arrival

How often are the HEPA filters replaced? Every flight? Every night? Once a month? 

 

As I understand it, a plane recirculates most (80%?) of the cabin air only while in flight when outside air is fed into the cabin. When the plane is on the ground the air inside is recalculating the cabin air only.

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Re: Plane HEPA air filters

Top Contributor

I don't know how frequently the filters are changed, but while parked at the gate ground based units send fresh air into the cabin. Cabin air is not just recirculated.

 

In flight, the air is completely replaced about every three minutes.

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Re: Plane HEPA air filters

New Arrival

How often are the filters changed? All modern (past 30 yrs or so I believe) commercial airplanes have HEPA filters... that’s not interesting. The interesting bit is how often the airline changes replaces them with clean ones.

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Re: Plane HEPA air filters

Employee
Employee
Solution

Hi @jvaleski, Southwest replaces the HEPA air filters onboard our 737s during routine maintenance cycles, which occur before the manufacturer’s recommended time limit. It’s just one more way we are committed to supporting the well-being of our Customers and Employees.

 

Nicole
Community Manager
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Re: Plane HEPA air filters

New Arrival

@NicoleAshley thank you for the information. are you able to give us a sense of how frequently that is in terms of time? does that mean the filters are change roughly once-per-day, week, month, year? just trying to get a sense of how to think about it in terms of actual time or flight-time or something. thanks!

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Re: Plane HEPA air filters

Employee
Employee

I don’t have the exact timing to share with you as it varies by aircraft series. However, the Southwest Technical Operations Team completes every air filter change as part of a scheduled, routine maintenance program before each filter’s recommended service date. Hope that helps!

 

Nicole
Community Manager