Health & Safety Understanding Conflicting Mask Recommendations Amid Delta Variant 5:20pm July 03, 2021 Health Share URL copied to clipboard! Copyright 2021 NPR. To see more, visit https://www.npr.org. 300x250 Ad More All Things Considered Delta is still cancelling hundreds of flights daily by Joel Rose Science Dark energy — which causes the expansion of the universe — may be changing by Regina Barber 300x250 Ad Support quality journalism, like the story above, with your gift right now. Donate