Air Travel

How Clean Is the Air on Planes?

Apprehension about aircraft cabin air is common during flu season. Here's what to know. 
A portrait of a young female passenger in the illuminator frame travel concept
Nadia Bormotova/Unsplash

It's that time of year again, when travel—or any indoor activity, really—comes with concerns of catching the flu. The combination of the annual surge of influenza activity with still-lingering COVID strains is enough to make even savvy travelers worried about stepping into a crowded airport or boarding a plane.

One of the paramount issues is determining if the air on planes hastens the spread of infection. But apprehensions about aircraft cabin air long predate COVID or active flu seasons. Before the pandemic, the Association of Flight Attendants—CWA was vocal about cabin air, as highlighted on its online Air Quality page, which details multiple concerns about shortages of oxygen and outside air, contaminated air supplies, and high concentrations of pesticides. In recent years these worries even spurred Congress to include further studies of contaminated air in the Federal Aviation Administration Reauthorization Act of 2018.

As for the flu, some experts predict a bad 2022-2023 influenza season for the U.S., after bellwether Southern Hemisphere countries like Australia and New Zealand, whose flu seasons run from April to October, faced severe outbreaks this year.

Here's a breakdown of how cabin air may affect airline passengers, this flu season and beyond.

Cabin air systems

At the onset of the pandemic, many airlines began publicly assuring passengers that their aircraft air filtration systems are state of the art at removing most viruses and bacteria. Airlines for America, the domestic industry’s primary lobbying group that represents major carriers like Delta, American, United, and Southwest, states: “Onboard, all A4A carriers have aircraft equipped with HEPA (high-efficiency particulate air) filtration systems and all members comply with or exceed CDC guidance.” 

The good news is that airlines calculate that their HEPA filters remove 99.7 percent (like ones used by United Airlines) to 99.999 percent (such as those in use on Delta Air Lines planes) of airborne particles, bacteria, and viruses, including strains of influenza and COVID. Most aircraft cabin air is “carefully controlled” and completely changed 20 to 30 times per hour with recirculation systems that blend some fresh air with up to 50 percent of recycled cabin air that pass through HEPA filters on “most modern aircraft,” according to the World Health Organization

Most airplanes in the U.S. are HEPA-equipped. That wasn't always the case: When the pandemic began, some of American Airlines’ regional jets didn't have the filters. In October 2020, however, the carrier's regional subsidiary Piedmont Airlines began adding the small-particle filters to its 50-seater planes. So even passengers on short city hops can rest assured the air is being rid viral microbes.

Such confidence is echoed by the industry’s global trade organization, the International Air Transport Association. “The risk of catching an infection on an aircraft is typically lower than in a shopping center or office environment,” IATA says. That assertion is backed up by an October 2020 study from the Harvard TH Chan School of Public Health, which found that HEPA filters and mask wearing reduced the risk of catching the virus on board planes compared to mask wearing during activities like grocery shopping or eating out. 

But some experts have expressed more doubt about the ability to completely scrub the air for zero chance of spreading flu and COVID. “Transmission of infection may occur between passengers who are seated in the same area of an aircraft, usually as a result of the infected individual coughing or sneezing or by touch,” WHO warns. Cabin crew members agree with this assessment. “It’s naive to think an airline can protect passengers 100 percent because you’re in an enclosed space for however long the flight is,” Heather Poole, a flight attendant and author of Cruising Altitude, says.

Another veteran flight attendant and labor representative who requested anonymity notes that close contact between those onboard—while boarding, in the aisles, and near the lavatories—allows exposure to the air people exhale before it reaches the filters. To help combat this some airlines, like United, started running the air filtration systems during boarding and deplaning, to maximize the overall effectiveness.

So if someone sneezes eight rows away, are you at risk? “Yes,” says Gary Peterson, International Vice President of the Air Division for the Transport Workers Union, which represents mechanics, flight attendants, dispatchers, and other airline employees. “The particles have to get into the system to be filtered. There’s no doubt the systems today are far superior than in the past.” The first step to cabin safety, of course, is for a sick person to choose not to board.

Experts say two other components are critical for breathing cleaner air in the skies: proper aircraft cleansing, particularly of surfaces near ventilation systems, and access to personal protective equipment, especially face masks.

Other health advice to consider

To stay healthy when flying, keep the following in mind:

  • If you’re concerned about aircraft cleanliness, try booking the earliest flight possible that day, as most airlines do a deep-clean each night. And if your itinerary allows it, consider nonstops rather than connecting flights, to limit your exposure to multiple dirty cabins.
  • Wipe down your airline seat and surrounding area with a sanitizing wipe to kill any lingering flu virus; pack an alcohol-based hand sanitizer and wash your hands often.
  • The CDC recommends that most travelers get a flu vaccine in September or October; it also advises to get up-to-date with your COVID vaccines and boosters before any travel.
  • Practice social distancing throughout your journey—at check-in, security screening, boarding, baggage claim, etc. Select seats apart from other passengers (often in the rear) and ask to be moved if possible.
  • Although there is no longer a mask mandate for air travel in the U.S., the CDC still advises travelers ages 2 years and older to opt to wear a face mask in indoor areas of public transportation—such as airplanes, trains, buses, ferries—and in transportation hubs like airports.

When these measures are taken together, it could significantly decrease your chances of contracting the flu or COVID during air travel.

Aside from germs and viruses, there are other factors that can affect how safe the air in a plane cabin is.

Noxious fumes

Most people have never heard the term “fume events,” but the aviation community has been studying these phenomena for years. In 2015, the International Civil Aviation Organization, chartered by the United Nations, issued guidelines for the industry. ICAO stated: “There are various types of fumes, smoke, haze, and mist that may contaminate the cabin and flight deck air supply system. The outside air may be contaminated with engine oil, hydraulic fluid, engine exhaust, ground service vehicle exhaust, fuel, de-icing fluid, or ozone.” ICAO added that recirculation fans, electrical systems, and other systems are “potential source[s] of contaminated air.”

Domestically, regulations require fume events be reported to the Federal Aviation Administration, but only in the case of “a mechanical discrepancy” in-flight—and the data is spotty.

What should you be concerned about? The International Air Transport Association cites a long list of symptoms, including chest tightness; difficulty with speech; dizziness; difficulty balancing; difficulty concentrating; and others. If you’re worried, seek medical attention and consider filing a complaint with the U.S. Department of Transportation.

Pesticides

The threat of diseases transmitted by insects, such as malaria, Zika, and yellow fever, has made spraying airplane interiors with insecticides common overseas.

In some countries including Ecuador, India, Panama, and Trinidad and Tobago, the preferred method is to spray while passengers are onboard to ensure travelers and their clothing are not carriers. The DOT also lists countries (including France, Italy, and the U.K.) that require disinfection on selected flights only, as well as countries (including Australia and New Zealand) that spray or treat the cabin while passengers aren’t onboard. In such cases, it’s important to avoid skin contact with surfaces still wet with pesticide.

The World Health Organization states it has “found no evidence” such insecticides are harmful to human health. But it cautions: “Some have reported feeling unwell after spraying,” and the CDC says there are “research gaps” and suggests more research and testing is needed.

The Association of Flight Attendants-CWA has called the spraying method a “bad idea” due to adverse health effects; and in 2019 the Association of Professional Flight Attendants received more than 200 reports of flight attendant illnesses—including respiratory problems, sore throats, and headaches—and the union believes these reactions were due to pesticide toxins.

If you have concerns about spraying, check with the airline before booking, as they do not inform passengers prior to ticket purchase.

This story was originally published in July 2017. It has been updated with new information.

Contributing reporting by Jessica Puckett