American and Southwest airlines now require masks, no doctors' excuses.

"Passengers who refuse to wear masks based on medical exemptions will no longer be able to fly on American Airlines and Southwest Airlines."

"On Wednesday, both air carriers announced anyone over the age of two must wear a mask while flying. Masks can only be removed to eat or drink, and Southwest's new policy states these instances should be "very brief."

"Both new policies apply to the entire travel experience. American indicates customers must wear face coverings "from the time they enter their departure airport and not remove it until they exit their arrival airport."

"American's new policy starts on July 29. After this date, if a medical condition prevents mask usage, customers will need to find alternative travel arrangements."

https://www.cnbc.com/2020/07/23/american-southwest-say-medical-exemptions-cant-be-used-to-avoid-masks.html