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When Finnson Liu moved from China to attend New York University, he brought with him the thin, black mask that had become both a style choice and a political statement in support of Hong Kong protesters.

He's since bought a new mask, a heavy-duty version meant to help prevent contagious illnesses, such as the new coronavirus. These days, there's no shortage of reasons for different kinds of masks.

"We see face masks as a symbol, but other people see face masks as a decoration," Liu said. "People wear them for multiple reasons."

Liu and people around the world have been given plenty of reasons in the past couple of years to cover up with masks. In November, India handed out millions of them at schools because of toxic air pollution in the nation's capital. Hong Kong banned masks, which protesters used to counter facial recognition technology. And most recently, the spread of the new coronavirus has sparked a run on surgical masks, despite their shortcomings in stopping the virus.

Liu, 18, a freshman at NYU, has been wearing masks since he was a high schooler in mainland China. Now, he's used to them. He likes how masks look.

"It's a trend," he said. "Somehow it makes you look a bit better."

Once almost entirely contained to hospitals, masks have been a common sight in East Asia for several years. But with the accessories now a part of the visuals of pressing global news stories — pollution, wildfires, government surveillance and the coronavirus — they're entering the mainstream. Billie Eilish, the teenage musician who swept the Grammys this year, often dons a mask as part of her wardrobe and collaborated with retailer Urban Outfitters to make a mask that is now sold out. Fendi has a "pollution mask" adorned with its logo that sells for hundreds of dollars. Instagram influencers have embraced them as a part of their looks.

It's a trend that offers a stark and unique image of modern life.

Henry Navarro Delgado, an associate professor at Canada's Ryerson University, who is focused on fashion and visual culture, said masks now serve a dual purpose: utility, in terms of safety and anonymity, as well as being a commentary on current events.

"This dystopian look, it is reflective of the times we are living in," he said.

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Masks have also become a global symbol of resistance to authority. Their use as a way to skirt ever-growing facial recognition systems is growing, particularly among anti-fascist groups, Delgado said.

"Anything you can put on your face to stop that process, that's what makes it possible to go undetected," Delgado said, making masks an effective, low-cost way to sidestep many facial recognition systems.

But the efficacy of masks for public health purposes is questionable, particularly depending on the type worn. Basic masks do not protect against airborne viruses, Also, some facial recognition systems can identify people even if they're wearing masks.

Some masks are designed to purposefully combine form and function.

Wendover Brown and her son founded the boutique Vogmask almost 10 years ago in San Francisco to create a stylish garment that would help people breathe cleaner air. Despite being ahead of the curve, even they have not been able to keep up with the demand brought upon by natural disasters and public health scares.

"We have a very sweet business without the panic situation," Brown said, citing their popularity with people who are immunosuppressed and asthmatic. "This isn't the sort of business we wanted to be in."

When the Camp fire razed 153,000 acres of California in 2018, Brown had to temporarily shut down her site. More recently, wildfires in California and Australia, a volcano eruption in the Philippines and the coronavirus outbreak have meant there is more demand than supply.

Brown said her masks filter out air particles but do little in the face of infectious disease.

"It becomes a symbol of protecting your own health," Brown said. "A $33 mask isn't going to save your life, but it can reduce risks."

While masks are becoming more common in the United States, there is still a significant cultural divide over what they represent. In parts of East Asia, the use of masks is seen as a general courtesy to others. In the U.S., there have been reports of verbal and physical attacks directed at people wearing them, particularly East Asian people. Recently, a woman wearing a mask was allegedly assaulted and called "diseased" in a New York City subway station in what appeared to be a coronavirus-fueled hate attack.

Health officials have warned that the U.S. could soon be hit by many more cases of the coronavirus, a scenario that could make masks a far more common sight among Americans.

Other times of outbreaks or broad societal challenges have similarly been met by trend shifts, including new accessories. Fashion historian Kimberly Chrisman-Campbell said that during the Medieval Era, doctors wore long-beaked masks filled with herbs they thought prevented contagion, and Marie Antoinette, the last queen of France, fashioned an "inoculation" hairstyle to encourage people to get the smallpox vaccine.

During World War II, people in England were required to carry around gas masks in preparation for possible attacks.

"It wasn't very glamorous," Chrisman-Campbell said of the WWII masks. So manufacturers began to make purses designed to hold them.

It's the kind of evolution that she said can quickly change the culture.

"Once these things become ubiquitous, people immediately start trying to make money off them," she said. "When protective clothing becomes a necessity, it quickly becomes fashionable."