Some shoppers at the King of Prussia mall skip masks even as coronavirus cases rise in Pa.

At the King of Prussia Mall, one of the biggest in the country, a large sign outside an entrance asked customers to mask up before they stepped inside to prevent the spread of the coronavirus through the nose and mouth. Meters away, a security guard ambled about with his mask slung below his chin.

He wasn’t alone.

Droves of customers at the King of Prussia Mall on a busy day this week also donned their masks like chinstraps. Others kept their masks below their noses. Several wore no masks at all as they window-shopped, scrolled through their phones, or talked at the 2.7 million-square-foot mall on a sunny Tuesday, the same day Pennsylvania health officials reported 995 new cases of the coronavirus in the commonwealth — the highest number in one day since May 10. The number ticked slightly down the next day with 849 cases, and to 719 on Thursday.

Customers and shopkeepers who followed safety protocol said they had noticed vast numbers of shoppers lax about wearing masks correctly at the mall, which reopened June 26. Some regarded it as dangerous and disrespectful.

“I don’t want to close again,” said merchant Jennifer Botelho, who sells preserved flowers out of a stall from midmorning to evening. “It’s a hard time for us. Everyone needs to be careful.”

Some took to social media to complain.

Among the reasons shoppers gave for shirking the mask, wearing one for long stretches of time was uncomfortable.

“It can get a little warm,” said Kenny Bigelow, 25, who had driven to the mall from Wilmington on Thursday to get out of the house and perhaps buy some outfits for his daughter. When he took off his mask for a short period of time, he said, he made sure to keep his distance from others.

Others who wore their masks did so resentfully. “There’s no rhyme or reason behind it,” one shopper said, then walked away.

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The number of coronavirus cases in Pennsylvania — where all 67 counties have moved in the green phase recently — has grown to 92,000 since it temporarily tapered off last month.

“Public mask wearing is most effective at stopping spread of the virus when compliance is high,” according to the Proceedings of the National Academy of Sciences of the United States of America, a peer-reviewed scientific journal.

It noted that visible enforcement, such as employees requiring customers to be wearing masks to enter stores, could improve adherence to public health directives. ”... Wearing any kind of cloth mouth cover in public by every person, as well as strict adherence to distancing and hand washing, could significantly decrease the transmission rate and thereby contain the pandemic until a vaccine becomes available,” the academy said.

Gov. Tom Wolf and Pennsylvania Health Secretary Rachel Levine have ordered that masks be worn outdoors if people are unable to stay six feet away from one another, in any indoor public area and health-care facility, on transportation, and at work. The policies are similar in New Jersey, where on Wednesday, Gov. Phil Murphy also mandated that people wear masks outside if they can’t socially distance themselves.

Yet around the region, from SEPTA trains to Jersey Shore boardwalks, compliance has been uneven.

Enforcement itself is difficult, Philadelphia Mayor Jim Kenney said at a news conference Thursday, where he hoped a $750,000 public awareness campaign to encourage proper mask-wearing guidelines with signs and slogans would “drive home the efficacy of wearing masks.”

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“We’re not at the point of taking people into custody or fining people at this moment,” he said.

The Centers for Disease Control and Prevention has directed the public to wear masks properly by covering the nose and mouth. ”Don’t put the covering around your neck or up on your forehead,” the agency said in its instructions.

A representative for Simon, the parent company of the King of Prussia Mall, pointed to its list of safety standards that “encouraged [customers] to wear facial coverings as recommended by the CDC,” keep six feet apart from others, and “perform a self-health check” before coming into the mall. Employees had their temperatures taken when they showed up to work, the company said, employees had been trained about safety guidelines, and security was directed to “actively remind and encourage” customers to social distance.

“We will encourage our tenants, vendors and contractors to implement this training,” Simon said.

A mall staff member said that security had been posted around the property and that each store had its own safety rules in place. He did not comment further.

“There doesn’t appear to be a uniform protocol,” said Emmett Shah, 49, a customer who sat in a sunny atrium at the mall, “so different sections are doing their own thing.” He wasn’t wearing a mask.

Apple and Sephora, among the most popular stores at King of Prussia, held customers to strict safety protocol. At Apple, customers spaced themselves well apart from one another and an employee used an infrared forehead thermometer on each customer before they stepped inside. Shoppers said staff asked customers to cover their noses and mouths with their masks.

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At the makeup chain Sephora, employees prohibited customers from touching makeup and said any samples would be brought out on a tablet-sized piece of clear acrylic plastic. “It’s a no-touch environment,” a staff member told shoppers spaced out in line outside the store, then reminded them to wear their masks “from nose to chin at all times.”

In the wing of the mall lined with a food court and high-end shops, employees contended with social distancing for long lines in an increasingly busy corridor. A queue of 37 people clustered outside the Gucci store, 21 outside the nearby Louis Vuitton, and 16 outside Hermès in a single afternoon this week. Customers were let in slowly, masks on.

Other shops were not nearly as stringent: Employees at an ice cream shop and pretzel stand had pulled their masks down. Of three employees posted at the entrance of a shoe store — an increasingly common practice to check that customers have masks and monitor the number of shoppers who enter to allow sufficient social distancing space inside — one had left her nose exposed. Another wore her mask on her chin so she could talk.

Recent analysis showed that in addition to coughing, talking could be a key source of coronavirus transmission, the National Academy of Sciences said, with “louder speech creating increasing quantities and sizes of droplets, which are associated with a higher viral load.”

The National Academy of Sciences said a mask as simple as a washcloth affixed to the head with two rubber bands could likely be effective enough to prevent the virus from spreading.

“Very few places will tell you to put your mask up,” Shah said as he sat in the mall, where shoppers — one dangling his mask off one ear — trickled in and out. “I don’t know why.”