American Airlines becomes the final major US carrier to ban masks with valves

If you're planning to fly with a mask that has a valve, think again.

On many U.S. carriers, you'll be asked to wear a different face covering and potentially face a ban on flying if you don't cooperate.

And when American Airlines' newly-strengthened mask policy goes into effect on Aug. 19, the Fort Worth, Texas-based carrier will become the latest — and largest — airline to bar flyers from wearing masks with valves.

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According to AA's Chief Customer Officer Alison Taylor, "wearing a face covering is a responsibility we all share. An effective covering, worn properly, is one of the best ways we can control the spread of COVID-19 to protect our team members and customers."

Masks with valves pose a problem according to the CDC. Though these face-coverings help protect the person wearing it, they may not help protect others around you. That's because the exhaust from the mask flows freely into the environment, meaning that your exhaled breath — or sneeze or cough droplets — are more easily expelled into the surrounding air.

Airlines are trying to create a safe environment for all flyers and employees. As such, it's no surprise that many carriers now ban masks with valves. Delta started the trend when it became the first U.S. carrier to formally bar flyers from wearing such masks.

Since then, most airlines have thankfully adopted a similar position. Of the largest U.S. carriers, Alaska, American, Delta, Frontier, JetBlue, Southwest, Spirit and United now all ban masks with valves.

Related: Why I hope every single airline follows Delta’s latest mask move

American's policy goes a little bit further though. In addition to valves, face coverings made of mesh or lace fabrics will no longer be accepted as of Aug. 19.

As the mask policies evolve, carriers continue to remove exceptions and add exclusions to the types of masks that aren’t safe. For instance, in July, AA stopped offering medical exceptions. Now, if you're above the age of two, you need to wear a mask or risk getting barred from the airline. Numerous airlines now have similar policies.

Without a federal mandate on masks during travel, airlines are scrambling to keep their policies current with what’s thought to be best practices. It seems like policies are getting modified every few days, making it hard to keep track of the latest developments.

Related: TPG's guide to airline health and social distancing policies

What's even harder though is enforcement. Gate agents and flight attendants already have so much to do to maintain a safe and timely operation. Asking front-line staffers to police the mask policies only adds more responsibilities to an already-full to-do list.

On top of that, employees will now need to take a look at each individual mask to confirm that it abides by the policy. And what's stopping someone from boarding with the appropriate mask, only to switch or take it off once airborne.

With a stronger policy, enforcement is easier. As more and more people are banned from the airline, flyers will likely feel pressure to abide by the policy. Plus, by taking a firm stance, customers hopefully internalize that the airlines are serious about enforcement.

Related: Delta has banned more than 100 passengers for not wearing masks

Either way, come Wednesday, make sure your mask doesn't have valves. By then, all of the biggest U.S. carriers, including American Airlines, will ban masks that are ineffective at preventing the spread of the virus.