(CNN)Health experts have long argued that face masks are critical to slowing the spread of the coronavirus and ending the pandemic. But some elected officials and their constituents still refuse to wear them.
Why you should wear a face mask even if your state doesn't require it
Last week, President Joe Biden criticized states, including Texas and Mississippi, for lifting Covid-19 restrictions, including mask mandates. He accused governors in those states of "Neanderthal thinking."
At least fifteen states -- representing 30% of the country -- don't require face masks.
With more than 500,000 Americans dead and new emerging variants of the virus, health experts warn that such policies could prolong the pandemic and result in more lives lost.
"We are not out of the woods. We haven't reached the end of the pandemic," said CNN medical analyst Dr. Leana Wen. "It's counterproductive and truly infuriating these governors are treating this as if the pandemic is over. It's not true."
"We could be at the precipice of a fourth surge, and we have a way to prevent it and that's keeping up our precautions for a while longer," she said.
Here are five reasons why experts say you should wear a face mask, even if your state doesn't require it:
The science is clear: Wearing face masks saves lives.
Numerous studies have shown that masks are the single most effective way to protect yourself and others from contracting the coronavirus, which causes Covid-19.
In counties that require masks, Covid-19 case and death rates slow down, according to the US Centers for Disease Control and Prevention (CDC).
Mask mandates were associated with a 0.7 percentage point decrease in daily rates of Covid-19 deaths up to 20 days after implementation and decreases of up to 1.9 percentage points up to 100 days later, according to new research published Friday by the CDC.
"Masks are a two-way street. Masks protect you and me" by preventing the spread of droplets and aerosol that may contain the virus, the CDC says in its mask guidance.
Dr. Anthony Fauci, the nation's top infectious disease expert, has even started wearing two masks.
"There are many people who take the commonsense approach," he told CNN. "If you're talking about a physical barrier -- and as the CDC recommends you want at least two layers within the mask as a physical barrier -- and you feel maybe more of a physical barrier would be better, there's nothing wrong with people wearing two masks. I often, myself, wear two masks."
The CDC last week released new data suggesting that double masking can significantly improve protection.
Layering a cloth mask over a medical procedural mask, such as a disposable blue surgical mask, can block 92.5% of potentially infectious particles from escaping by creating a tighter fit and eliminating leakage, researchers said.
The United States has made a lot of progress in the fight against Covid-19, including the development of safety protocols, enhanced treatment plans and vaccines.
The rates of infections, hospitalizations and deaths have decreased in many states since January, and nearly 90 million doses of vaccines have already been administered.
But abandoning face masks now could reverse those gains, health experts warn.
With tens of thousands of Americans still being infected daily, and more transmissible variants discovered, it's more important than ever to wear face masks and follow other safety guidelines.
"Please hear me clearly: At this level of cases with variants spreading, we stand to completely lose the hard-earned ground we have gained," said Dr. Rochelle Walensky, director of the CDC.
"I am really worried about reports that more states are rolling back the exact public health measures we have recommended to protect people from Covid-19," she said. "Please stay strong in your conviction. Continue wearing your well-fitting mask and taking the other public health prevention actions that we know work."
Health experts say that vaccinated people should continue wearing face masks, for their protection and the safety of others.
None of the three authorized vaccines -- Pfizer-BioNtech, Moderna or Johnson & Johnson -- are 100% effective. Continuing to wear a face mask after receiving a vaccine could provide additional personal protection.
It could also help stop the spread of Covid-19. That's because the vaccines are effective at preventing symptomatic illness and severe disease. But it's not clear they prevent people from becoming asymptomatic carriers and spreading it to others.
Wen said Americans will need to continue wearing masks until we reach herd immunity.
"It's estimated that about 70% of Americans must be vaccinated before we get to herd immunity through vaccination. That's the point where enough people have the immune protection that the virus won't spread anymore," she said. "This means about 230 million Americans must receive the vaccine."
In states without mask mandates, people who wear them can feel out of place.
They should continue wearing them anyway, health officials say, not as a political statement, but as a sign of respect to vulnerable community members.
Many people, including seniors and the immunocompromised, face a much higher risk of severe illness and even death from Covid-19. Wearing a mask shows that you care about their well-being.
"This is not about politics," Wen said in July. "This is about each of us showing that we care about one another, that we respect one another."
Dr. Joshua Barocas, an infectious diseases physician at Boston Medical Center, echoed her sentiment.
"I think beyond simply the viral transmission, wearing a mask can just be a symbol," he said. "It can show people that you are committed to the cause, that you're committed to fighting Covid-19 as a community...committed to protecting other people's lives and their children's lives and their families' lives...committed to having a strong economy open when we're fully ready."
The pandemic has cut people off from family, friends, work, school, religious services and more.
Refusing to wear a mask won't bring any of that back. All it does is further delay our return to normalcy and make life a lot more dangerous, experts say.
"People say, 'When is it going to get back to normal and I don't have to wear my mask anymore?'" Wen said. "That's not the right way to think about this. We want our businesses to come back, we want our churches to be open for in-person service and our schools open for in-person learning. We need masks to do that."
Wen said it all begins with our mindset. The faster we realize that masks don't limit, but enable, us to return to normal, the quicker we'll get there.
She said mask wearers and non-wearers ultimately want the same thing: for the country to return to normal.
"We are so close to the finish line, and that's the most tragic part of it all. If you just hang in there for a bit longer, we'll put an end to this pandemic," she said.