Wracking people's brains a lot these days is knowing when it's right -- and safe -- to shed the mask indoors or in large crowds.

Getting back to normal, it turns out, isn't so easy.

Across the greater Philadelphia region, the only jurisdiction left where masks are actually required of fully vaccinated people indoors is in Philadelphia. But there are other places like medical facilities and on public transit where masks are still required.

That doesn't mean everyone is comfortable shedding their mask just yet. How can you know you're safe indoors? Does a particular business still enforce an indoor mask policy? Meanwhile, what should you do if you see someone without one on in a setting that makes you uncomfortable? The biggest variable before answering those questions is whether you are vaccinated or not.

If you're not vaccinated, wear your mask all the time indoors and whenever you're in crowds outdoors.

For vaccinated people in settings that fall into a gray area -- like at a packed baseball game or inside a church -- do what makes you feel comfortable as long as the rules allow. The Centers for Disease Control say vaccinated Americans have little to worry about in most indoor and outdoor settings. But if that doesn't ease your mind, Dr. Thomas Fekete, an infectious disease expert and Thomas Durant Chair of Medicine at Temple University, says it never hurts to don your face mask.

Still, it's not worth your time to get angry or confrontational if someone else seems to be flaunting the rules, Fekete says.

"This shouldn’t be a matter of great crisis. This is a public policy decision we struggled with for over a year. Some people like the tussle, the conflict. I think we need to let go of that," Fekete said. "Whatever the rules are, try to be cognizant of them. Try to follow them to maintain civility, but it’s not a grudge match."

There only remains "a limited number of places" where fully vaccinated Americans should remain vigilant in masking, Fekete said. Some examples are:

• In a healthcare setting, like a hospital or nursing home, where vulnerable populations are staying or reside.
• On an airplane or within close quarters with strangers for hours at a time.
• On public transit like SEPTA. The transit agency has lifted COVID-19-related capacity limits, but mask-wearing is still required.

"The vaccine is very good, excellent, but not perfect. Part of this is your perception of risk, how you handle risk," Fekete said. But for those who are fully vaccinated and in good health, he added that they needn't worry too much when they come across someone else without a mask.

"Don’t get mad. It’s not a life and death for most people."

Here are the mask-wearing rules by state and in Philadelphia:

Pennsylvania

Fully vaccinated people are no longer required to wear masks indoors or outdoors, as of May 31. However, one caveat is that businesses and institutions can continue to require masks in their establishments if they so choose. Those who are not vaccinated must continue to wear masks at all times indoors until June 28, or until 70% of the state's population is vaccinated, whichever comes first.

There are some places where masks are still required, per state law: hospitals, nursing homes and prisons.

Philadelphia

Masks are still required indoors for everyone, though city officials say they are still examining the new daily case counts and could change the mask mandate as soon as June 11. Some large institutions like the Archdiocese of Philadelphia have to juggle with enforcement of face masks for the time being: in the archdiocesan churches outside of Philadelphia -- in Bucks, Delaware, Chester and Montgomery counties -- parishioners don't have to wear a mask when attending Mass.

In Philadelphia, Catholics still have to wear a mask at church.

New Jersey

The mask mandate is over, as of May 28. However, people who are not fully vaccinated are urged to continue wearing their masks for their own safety and the safety of others around them, particularly those with immuno-deficiencies.

"Please be responsible and do the right thing – for your own safety and your community’s safety," Gov. Phil Murphy said.

Businesses and institutions in the Garden State can still enforce their own mask requirements, just like in Pennsylvania.

Delaware

The First State became an early adopter of the CDC's guidelines that eased the requirement of face masks in all but a few indoor settings. As of May 21, the mask mandate was lifted in Delaware except for hospitals, nursing homes and other congregant settings like prisons.