UPDATE: We traveled this past week for the first time since the mask requirement was lifted and what a huge difference it made in my DH oxygen level. His level remained above 90 the entire time so he didn't need to use his inogen machine. With a mask on (without the machine) it would drop to the 60's and his heart rate would remain about 115 bpm. He always said that if Covid didn't kill him, the mask would. We will keep taking it along with us, but I sure hope the mask mandate stays lifted!