(Bloomberg) — JetBlue Airways Corp. will require customers to wear face coverings during travel, a first for U.S. carriers in the age of the coronavirus pandemic.

Under the new policy starting May 4, passengers will have to cover their nose and mouth throughout their trip, JetBlue said in a statement Monday. That includes when they check in, board the plane, fly and exit the aircraft. The New York-based carrier is also asking customers to follow the same rule in airport terminals.

“This is the new flying etiquette,” JetBlue Chief Operating Officer Joanna Geraghty said in the statement. “Onboard, cabin air is well circulated and cleaned through filters every few minutes but this is a shared space where we have to be considerate of others.”

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The new requirements signal a major potential shift in commercial flying as airlines look to coax people back onto planes and soothe concerns that aircraft cabins will foster the spread of Covid-19. JetBlue said the policy is based on guidelines from the U.S. Centers for Disease Control “that indicate all individuals should wear a face covering in public to help slow the spread of the coronavirus.”

United Airlines Holdings Inc., Delta Air Lines Inc. and American Airlines Group Inc. already require some employees to wear face masks or will do soon. American will start providing face masks and wipes next month to customers who want to use them.

Small children are exempt from the face-covering rule on JetBlue flights.