Is It Really Time to Take Off Your Mask on Public Transit?

Mask mandates are being lifted nationwide. Several airlines, including Delta, American Airlines, Southwest, and JetBlue are no longer requiring customers or employees to wear a face mask in terminals or when aboard an aircraft. Many ground transportation options like trains, subways, and buses have also ditched masking restrictions.

The changes come after a federal judge in Florida struck down the Centers for Disease Control and Prevention (CDC)’s mask mandate for airplanes and other modes of public transit on April 18.

The Transportation Security Administration (TSA) recently put out a statement saying that they will no longer enforce mask use on public transportation and transportation hubs. But the CDC currently recommends that everyone—including passengers and workers—wear masks on all public transportation and hubs.

Even though masks are no longer mandated and won’t be enforced, travelers and workers still have the option to wear one. But how risky is it to go maskless on public transit?

What Is Your Risk on Planes?

The risk of contracting COVID-19 on an airplane is considered low compared to other indoor settings because of how air circulates and is filtered on an aircraft.

Amesh Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health, told Verywell that planes aren’t the highest risk indoor spaces because air is exchanged frequently and high-efficiency particulate air (HEPA) filters are used.

These filters remove and minimize the spread of small dust, pollen, mold, bacteria, viruses, and any airborne particles from the air.

“Airplanes have pretty aggressive air handling that’s not comparable to almost any other indoor setting,” Adalja said. “They exchange the air in the cabin very frequently, meaning that there’s a high level of ventilation.”

All that moving air means less risk. Adalja explained that “we know that the more ventilated an area is, the less likely those particles are to linger or to not be able to reach people [because] they get dispersed and diluted much faster.”

What Research Has Shown

Several investigations have provided evidence of lower COVID-19 transmission on airplanes.

For example, a report by the Department of Defense found that ventilation and filtration systems on planes helped reduce the risk of airborne COVID-19 exposure by 99%.

In October 2020, the United States Transportation Command reported that aerosol particles were quickly diluted due to the high air exchange rates in a typical aircraft cabin. Certain aircraft also removed particulate matter an average of more than eight times faster than a typical home ventilation system.

But That Doesn’t Mean You’re in the Clear

Emily Landon, MD, associate professor of medicine and executive medical director for infection prevention and control at the University of Chicago Medicine, told Verywell that while filtration and ventilation systems can help reduce the risk of virus transmission on a flight, there are other factors to consider.

For example, close contact with a person who has COVID-19, how well ventilation systems are working, and whether or not people are masking can affect a person’s risk.

“It doesn’t matter how great the airplane’s ventilation system is. If someone in that area around you—two seats behind, to the side, in front, and then on diagonals—has COVID, you are at a pretty high risk of getting it,” Landon said. “If the person around you has COVID and is not wearing a mask and you’re not wearing a mask, the risk goes up because you’re just relying on your vaccination and your immunity at that point.”

Landon added that the majority of transmission happens when small droplets—particles that are generated when people breathe, talk, or cough—spread through a space.

If you are in close contact with other people (less than six feet away, according to the CDC), you can get COVID-19 even if there’s good ventilation because you’re in the stream where others are breathing, coughing, and expelling droplets into the air.

John Volckens, PhD, professor of mechanical engineering at Colorado State University and an expert in air quality and exposure science, told Verywell that how long you are in a room with someone who might have COVID-19 can also increase your risk of infection.

In most cases when people are traveling by plane, they are likely to be on board for more than 15 minutes.

According to Volckens, one reason planes can be risky is that you’re in them for longer—and the ventilation isn’t always on.

“It’s true that airplanes have great ventilation—but only when the ventilation is running,” Volckens said. “They typically don’t turn on that higher performance ventilation until the plane door closes and it takes off.

Volckens pointed out that when there’s not a lot of ventilation, you’re inhaling the exhalations of the people around you.

What Is Your Risk Elsewhere?  

Adalja said that since other indoor spaces—like airport bars, dining areas, and boarding gates—do not have the same air handling or ventilation process that planes have, they carry a higher risk of infection.

“There’s not the same level of ventilation in an airport bar, for example, as when on an airport plane,” Adalja said. “And there may not be the same level of HEPA and filtration in the physical room that the bar is in.”

In terms of how particles are moving around in a space, Adalja added that “there’s going to be more particles when people are drinking, talking, and laughing than when you’re sitting or waiting in line for your group number to be called.”

Landon noted that while the risk might be higher in some indoor areas, it also depends on how long you are spending there, how many people are around you, how big the space is, how often the air is flowing, and if there is good ventilation.

Buses, trains, subways, and ride shares typically don’t have HEPA filters or frequently recycled air. Ground transportation also tends to be crowded.

Volckens said that while these factors can increase infection risk, it goes up significantly when you are physically close to an infected person—especially if you are not wearing a mask.

“The more people you have, the more likely it is that one of them has COVID,” Landon said. “If you’re only sitting next to one person, you’re only going to be there for a few minutes and you keep your distance from people, then the risk is pretty low compared to if you’re stuck on a train with someone who’s hacking away for seven hours.”

Overall, Volckens said that “you are probably less safe on a train or bus than you are on a plane because there’s not much ventilation.”

Masks Protect You

Research has shown that wearing a mask helps prevent the spread of COVID-19—even if you are the only person in a space that’s wearing one.

For example, CDC data found that people who reported wearing N95 masks while indoors were 83% less likely to test positive for COVID-19 compared to people who never wore a mask inside.

Another study from December 2021 showed that plane passengers who were sitting in the same row or one row away from someone who was infected with COVID-19 had a high risk of getting infected through droplets. However, the people who were wearing a mask reduced their risk of infection by 54%.

“People are moving around and going place to place, which means you’re going to be seeing different people so you could be actually transmitting the virus and introducing it to new communities,” Landon said. “From a public health standpoint, there’s no doubt that people should still be wearing masks on public transportation.”

While no mitigation measure is 100% effective, Landon said that wearing a mask to add that extra layer of protection can help reduce your risk of getting infected or spreading the virus to others when you’re traveling.

Volckens and Adalja added that people should also assess their own risk when they’re deciding whether to wear a mask or not in certain situations.

Older adults, people with certain health conditions, and people who are immunocompromised may need to take more steps to protect themselves. Also, people who live with others who are in high-risk categories may need to take more precautions to avoid spreading the infection to a vulnerable person.

When thinking about individual risk, you’ll also need to factor in your COVID-19 vaccination and booster status.

“You can never get the COVID risk down to zero, it will always be there,” Adalja said. “People have to learn how to decide what risk is acceptable to them and to think about their risk factors for severe diseases, especially if you’re someone that falls into that high-risk group.”

How to Lower Your Risk

Although the risk of getting COVID is higher in some mass transportation and indoor settings, Landon said there are steps that you can take to protect yourself:

• Continue to wear a mask in crowded and enclosed areas, like buses and trains, even if it’s not required.
• Open windows when you can, including when you’re in a car or van that’s using a ride-sharing app.
• Eat or drink in areas that are not crowded, especially at airport restaurants and boarding gates.
• Social distance from people who aren’t wearing a mask as well as you can.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.