The Wikipedia snippet below is not backed by a reliable source. Can you find one?
Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!
In page HEPA:
"Modern airliners use HEPA filters to reduce the spread of airborne pathogens in recirculated air. Critics have expressed concern about the effectiveness and state of repair of air filtering systems, since they think that much of the air in an airplane cabin is recirculated. Almost all of the air in a pressurized aircraft is, in fact, brought in from the outside, circulated through the cabin and then exhausted through outflow valves in the rear of the aircraft.
You can customize Citation Hunt by importing a list of articles into it. This gives you a link that you can share with others so they browse Citation Hunt limited to the articles you provided.
Where would you like to import articles from?
Please enter Wikipedia article titles to import, one per line, in the area below:
PetScan is a tool for querying Wikipedia and defining lists of articles. PetScan assigns IDs to queries so their results can be imported into other tools.
Please create your query in PetScan and paste its ID below:
Tip: Citation Hunt only contains articles inside the All_articles_with_unsourced_statements category. For better results, you can use PetScan to only retrieve articles inside that category.
Please wait, your custom Citation Hunt is being computed. This may take a few minutes…
You can press Back or close this dialog to cancel.
Your custom Citation Hunt has been created!
You can copy and share the link above to allow other people to use it, or start browsing it now!
Sorry, your custom Citation Hunt failed to be created or came up empty!
Please try again and keep the following tips in mind: