Gov. Greg Abbott just ordered residents of most Texas counties to wear face coverings in public. Those who don't could face a $250 fine.

• Gov. Greg Abbott of Texas issued a face-covering mandate Thursday for all residents of counties with at least 20 coronavirus cases.
• The state joins 20 states and various other cities and counties in requiring face coverings to prevent the spread of the novel coronavirus.
• Texas added 8,000 new coronavirus cases on Wednesday, an all-time high. The state has reported more than 178,000 total cases.
• A growing body of research suggests that masks and other face coverings can prevent coronavirus transmission and save lives.

Gov. Greg Abbott issued a sweeping order Thursday requiring residents of counties with at least 20 coronavirus cases to wear a face covering.

The mandate applies to people inside businesses and outdoors in places where social distancing is not possible. First-time offenders are to receive written or spoken warnings, and after that a fine of up to $250 is possible. The order specifies that no one should receive jail time.

The announcement came a day after the state hit a grim milestone: more than 8,000 new COVID-19 cases in one day — a state record. (For context, New York reported 11,571 cases on its worst day of the outbreak, April 15.) Texas also recorded 57 new deaths, its second-highest daily death toll, according to ABC13 Houston.

In total, the state has confirmed more than 178,000 cases and 2,500 deaths, according to data from Johns Hopkins University.

Last week, Abbott paused the state's reopening plan, calling the new surge in cases a "massive outbreak."

In addition to Texas, cases are going up in at least 37 other states. On Wednesday, the US surpassed 50,000 daily new coronavirus cases for the first time.

A growing body of research suggests that face masks can effectively prevent coronavirus transmission. A model from the University of Washington projects that if everyone in the US were to wear a mask in public, about 24,000 lives could be saved over the next three months.

More than 20 states require face coverings in public

Texas has joined a growing list of states — along with Washington, DC — that require face coverings in public: Arizona, California, Connecticut, Delaware, Hawaii, Illinois, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Nevada, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, and Washington.

Some cities and counties in states without statewide orders also have local requirements to wear masks, such as Anchorage, Alaska; and Jacksonville, Florida.

Still, many local public-health officials have had difficulty enforcing mask requirements, since the policy has become politically charged.

In Texas, the new mask mandate is a reversal: Abbott previously prohibited local governments from punishing people who do not wear masks when the state's stay-at-home order was lifted.

But Abbott said in a video released Thursday that the latest coronavirus numbers "reveal a very stark reality."

"COVID-19 is not going away," he said. "In fact, it's getting worse."

Masks can help prevent coronavirus infections

Both the US Centers for Disease Control and Prevention as well as the World Health Organization now recommend that people wear cloth face coverings in public settings, especially in areas with significant community spread. The CDC recommends that surgical masks or N95 respirators be reserved for healthcare workers.

Face coverings make a difference because coronavirus particles pass between people in tiny droplets of saliva and mucus. If a sick person sneezes, coughs, talks, or eats near someone else, the particles could land on that person and enter the eyes, nose, or mouth. Covering our noses and mouths helps block those particles.

Studies and models have attempted to quantify the benefits of mask wearing. Recent research from UK scientists concluded that the more people wear masks in a community — even if the masks are only 50% effective at blocking the virus — the closer it can get to containing an outbreak, even without a lockdown.

"These results are striking in that the benefits accrue to the face mask wearer as well as to the population as a whole," the researchers wrote. "There is, therefore, a clear incentive for people to adopt face mask wearing."

According to an analysis by The Philadelphia Inquirer last week, coronavirus cases seemed to be rising overall in states with relaxed face-mask rules. By contrast, The Inquirer found that new cases had fallen by 25% in total over the prior two weeks in states that mandated masks in public.

In May, two hairstylists in Springfield, Missouri, offered a case study in mask effectiveness. They tested positive for COVID-19 after having seen 140 customers. But local public-health officials found that of the 46 salongoers tested for the virus, not one was positive.

"Which mask worked, the hairdresser's or the client's? I think the answer is yes. They both worked," Robin Trotman, an infectious-disease specialist in Springfield, told The Washington Post. "The system worked. Universal masking worked."