The order goes into effect at 11:59 p.m. Monday.

The coverings must be worn over both the nose and mouth while waiting, boarding, traveling and disembarking, it said. The masks need to be at least two or more layers of breathable fabric and needs to be secured to the head with ties, ear loops or elastic bands, according to the order.

The CDC said it reserves the right to enforce the order through criminal penalties, but it “strongly encourages and anticipates widespread voluntary compliance” and expects support from other federal agencies to implement the order.