Recirculating Air
 

This subject has been hotly debated ever since the system was introduced, but with the publicity which recent epidemics have attracted, have we a specific explanation that aviation is not spreading all sorts of nasties around the world?

Can anyone explain what filtration system is used and how efficient it is?

HEPA Filter
 

Boeing use a HEPA Filter which traps the virus particle so whilst the virus may be present from an infected passenger once it passes through the said filter as part of the recirculation process the air is clean.

ultraviolet
 

Why is recirculated cabin air not passed through ultraviolet light, which is said to kill most airborne germs.

simples!

Virus is a virus and a germ is a germ.
Close the door on your way out,

Next patient please.

not quite yet
 

In response to your very brash and arrogant reply,

yes a virus is a virus (obviously), and a germ a germ (again obvious, you are so clever to point that out)

But as i was using just a term of phrase.

i ask you to further your research and broaden your tiny mind, and look up UV light germ/virus. This will show you that it kills not only germs but viruses as well.

engage brain first!

Slyguy,

UV isn't used because typically the air velocities in the air con systems on aircraft are too high (dwell time is not sufficient) for the UV as efficiently deactivate the bacteria/virus as the currently installed HEPA filters is at blocking its passage. There are some prototype UV systems knocking about, but they've not gone further - apart from dwell time there's pressure drop, maintenance cost, reliability and weight that all play against UV on aircraft.

HEPA filters are installed on Airbus - don't know about the smaller regionals. Numerous studies have shown the efficiency of HEPA. The main transmission method on aircraft is person to person (and that's before you look at the whole travel experience, queuing at check-in and security, mixing in the terminal with people from goodness-knows-where, etc.)

Hope that satisfies your curiosity :ok:

Edited to note that the filter suppliers quote 99.97% efficiency for HEPA filters.

So we need a space suit made out of this filter if we are to survive a pilot career.

okay wbble, lets widen the issue:-

How is it that aircraft airconditioning systems are not designed to ensure no contamination products are circulated?

Let's not widen the issue to include contaminated air. This already has a number of its own threads.

Cheers,

BM