Residents in Laredo, Texas, are being told they must wear face masks when entering a building, public transit, or outdoor gas station. If they don't comply, they could be fined up to $1,000.

The ability of face masks to prevent coronavirus spread has been up for debate due to limited research and short supply for those who need protective gear the most.

According to the World Health Organization, face masks should be reserved for healthcare professionals, sick people, and their caretakers.

Healthy people don't need to wear face masks right now, but WHO said this could change as new information comes out.

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Anyone over the age of five years old who walks around Laredo, Texas, without their mouth and nose covered could now be fined up to $1,000.

The move, brought into effect on April 2, is an attempt to stop the spread of the coronavirus in the small Texas town, despite the financial burden such a fine could have on locals, and the fact that masks are not the most effective way to prevent the spread of the virus.

"I'd rather bury them in debt than bury them in a coffin," councilman George Altgelt told the Morning Times.

Residents can use anything to cover their faces, the Laredo Morning Times reported, whether it's a mask, bandana, scarf, or any fabric they have available, although there's no evidence a bandana or a scarf would be effective. They must use it when entering a building, public transit, or an outdoor gas station.

The directive is controversial: the World Health Organization is still advising the general public not to buy masks to wear, given the global shortage of masks, which are needed by healthcare workers, who are most exposed to the virus.

There's limited research on face mask effectiveness for healthy people

On April 1, the World Health Organization director-general Tedros Adhanom Ghebreyesus said they are still not advising everyone to wear surgical masks: only healthcare professionals, sick people, and their caretakers, should wear them.

"We're continuing to study the evidence about the use of masks. WHO's priority is that frontline health workers are able to access essential personal protective equipment, including medical masks and respirators," Tedros said.

Currently, few studies exist on the effectiveness of face masks for preventing disease spread. Of the randomized control trials that do exist, many suggest that people sometimes wear a face mask incorrectly, which could have contributed to the negative results.

"Randomized trials don't support a big effect of face masks, but there is the mechanistic plausibility for face masks to work, right? So why not consider it?" Ben Cowling, a professor of epidemiology and a mask researcher at the University of Hong Kong's School of Public Health, previously told Business Insider. "If you don't wear the mask properly, and if there's a lot of chances for you to get infected, then the mask may not do a lot of good."

The more people buy up surgical masks, the less protection healthcare workers will have

There is global shortage of face masks, which complicates the question about what the advice should be on face masks.

Health officials are urging the general public that face masks won't serve them, but also say that the masks are effective and necessary for medics to protect them from the virus. Mike Ryan, WHO's executive director of health emergencies, agreed in a press conference this week that officials are trying to make sure their advice protects the public, but also does not fuel a shortage in areas where the masks are most needed.

"Where should these masks be, and where are the best benefits?" Ryan asked a reporter during a press briefing on Monday.

"Because one can argue that there's a benefit of anything, but where does a given tool have its most benefit? And right now, the people most at risk from this virus are frontline health workers who are exposed to the virus every second of every day." He added that "the thought of them not having masks" was "horrific."

At the same time, Tedros said it's possible the WHO could change its stance on who should wear the protective garment as we learn more about the virus.

"WHO continues to gather all available evidence and continues to evaluate the potential use of masks more broadly to control COVID-19 transmission at the community level," Tedros said. "This is still a very new virus and we're learning all the time. As the pandemic evolves, so does the evidence, and so does our advice."