On a sunny Friday morning, Lindsey Baker was waiting at a bus stop across from Carlow University in Oakland. Clad in typical summer clothing — shorts and a T-shirt — Ms. Baker, 23, was biding her time for a bus to take her to Robinson, where she works as an assistant manager at the clothing store Maurices. But one piece of clothing she was wearing is becoming increasingly unnecessary in Pittsburgh and Pennsylvania — a mask. The Pennsylvania Department of Health is lifting its order requiring universal face coverings on Monday, but this doesn't apply everywhere. The Centers for Disease...