Effective immediately, masks are mandatory in all public spaces in Pennsylvania.

Individuals are required to wear face coverings if they are:
outdoors + unable to consistently maintain a distance of 6 feet from individuals who are not members of their household

in any indoor location where members of the public are generally permitted
waiting for, riding on, driving, or operating public transportation or paratransit or while in a taxi, private car service or ride-sharing vehicle

obtaining services from healthcare sector in settings including, but not limited to, hospital, pharmacy, medical clinic, laboratory, physician or dental office, veterinary clinic, or blood bank
engaged in work, whether at workplace or performing work off-site

(con't) when interacting in-person with any member of the public, working in any space visited by members of the public, working in any space where food is prepared or packaged for sale or distribution to others, working in or walking through common areas,

(con't) or in any room or enclosed area where other people, except for members of the person's own household or residence, are present wherein unable to physically distance

More about the requirement: https://bit.ly/3gilofr