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Are masks needed on planes? Airlines say ventilation systems make cleaner air than in your office

Visual explainer: HEPA ventilation systems on airplanes filter & replenish air to reduce COVID transmission – but masks still provide extra protection

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Passengers on planes, trains and other public transportation won’t be required to wear masks, at least for now, after a federal judge in Florida voided a national mandate Monday.

Airlines came out against mask mandates, saying aircraft ventilation systems made transmission of the coronavirus unlikely. After the judge's ruling, the largest airlines in the USA said they will not require masks.

The Centers for Disease Control and Prevention still recommends that masks be used. The Justice Department is appealing.

The mask mandate, announced in January 2021, required people to wear masks while using public transportation and facilities. It was set to expire April 18. The CDC said April 13 that it would extend the mandate for 15 days to study the BA.2 omicron subvariant of the coronavirus.

The subvariant is more contagious than previous versions and is estimated to have caused 90% of new COVID-19 cases in the northeastern USA, the CDC said.

Passengers may continue to wear masks if they wish. 

How do aircraft ventilation systems work?

The International Air Transport Association, a trade association of the world's airlines, says the quality of air inside a commercial aircraft is better than that of most indoor spaces.

IATA says air aboard aircraft cabins is exchanged about 10 times more often than in most office buildings, making risk of transmission low. Part of the reason is the cabin layout:

  • Passengers face forward.
  • Seatbacks serve as air barriers.
  • Air flow is from the top of the cabin to the bottom.
  • Cabin air is filtered.

Most airplanes use high-efficiency particulate air filters. The Environmental Protection Agency says HEPA filters can remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 microns. Research found HEPA filters can catch coronavirus particles.

Boeing and All Nippon Airways say the volume of cabin air in aircraft is constantly moving and is exchanged every two to three minutes.

Jet engines draw air from outside the aircraft into the ventilation system.

The air is filtered and cooled and moved to overhead ducts.

The air is moved primarily from the ceiling to the floor, to limit spreading of particulates.

About half of the "used" air is discharged outside the aircraft. The rest is filtered, mixed with filtered air from outside and recirculated inside the plane.

The catch is that aircraft's main engines must be operating to power the ventilation system. That means the plane must be in flight.

On the ground, commercial jets have an onboard auxiliary power unit that can be used to operate the system. Fresh air can also be pumped in from an outside air compressor.

Do ventilation systems provide enough protection?

Studies on risks of SARS-CoV-2 transmission aboard airplanes say ventilation systems work well, but masks provide extra protection. 

  • In 2021, a Journal of Travel Medicine review of 18 studies said transmission can occur aboard airplanes and noted "masks may reduce the probability of infection on an airplane by an average of 47% to 86%," depending on the type of mask.
  • In 2020, a study by the Journal of the American Medical Association said the risk of getting COVID-19 while traveling by air is low. The study said airflow in jets is "much faster" than in buildings, but it noted, "Any remaining risk to be managed is from contact with other passengers who might be infectious."
  • In 2020, a Harvard University study said aircraft systems are highly effective, but "face mask requirements are perhaps the most essential layer of a comprehensive set of measures to reduce transmission of COVID-19 throughout air travel."

In her ruling Monday, U.S. District Judge Kathryn Kimball Mizelle in Tampa said the CDC exceeded its authority, failed to justify the order and didn't follow rulemaking procedures in extending the mandate.

The Transportation Security Administration said it would "no longer enforce its Security Directives and Emergency Amendment requiring mask use on public transportation and transportation hubs." 

Airplane passengers cheer as mask mandate is lifted on public transportation
Passengers on flights across the country cheered as mask mandates were lifted for airplanes and other forms of public transportation.
Cody Godwin, USA TODAY


CONTRIBUTING Chris Kenning and Adrianna Rodriguez

SOURCE USA TODAY Network reporting and research; The Associated Press; Boeing; Environmental Protection Agency; International Air Transport Association; All Nippon Airways

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