A doctor wore 6 face masks at once while testing his oxygen levels, and found he could still breathe perfectly

• Wearing a face mask helps prevent the spread of the novel coronavirus.
• Still, some people refuse to wear masks, falsely claiming that the cloth shield causes their oxygen levels to drop.
• A doctor debunked this common myth by filming himself testing his oxygen levels while wearing six face masks.

Despite overwhelming evidence that face masks effectively reduce the spread of the novel coronavirus, some people still refuse to wear masks.

In Ireland, where mask-wearing last week became legally mandatory on public transport and in shops, general practitioner Maitiu O Tuathail saw an influx of patients panicking about wearing them. They had read false claims on social media that face masks can lower blood oxygen levels and even cause brain damage.

One patient (a mask-wearer) suggested O Tuathail post a video to counteract these claims, so he filmed himself testing his oxygen levels while wearing not one but six surgical face masks.

His oxygen level remained stable at 99 percent as he donned as many masks as his ears could handle.

"That's consistent whether you wear six masks for one minute or for the entire day. The level of oxygen in your blood won't change," O Tuathail said.

Wearing a mask won't affect your oxygen levels, even if you wear it all day

Some commenters said that, while O Tuathail's oxygen levels were stable for the duration of the video, he didn't demonstrate what would happen if he wore a mask all day or while exercising.

He said his surgeon friends have no trouble wearing masks for hours on end during work. One of his colleagues commented on his post saying that she had measured her oxygen levels while performing a lengthy procedure with a mask on, and they remained stable.

Wearing a homemade cotton mask also won't have an effect on your oxygen levels.

"Because oxygen molecules are so tiny, they can permeate through whatever it is you put on your face, no matter how long you leave it on your face for," he said.

Some people with asthma have lower oxygen levels, but wearing a mask won't make them worse

Another common misconception is that people with certain medical conditions like asthma and chronic obstructive pulmonary disease shouldn't wear masks because they have extra difficulty breathing.

People with COPD regularly have decreased oxygen levels closer to 92 percent, O Tuathail said, but wearing a mask won't lower their levels any more than normal.

While wearing a mask may be uncomfortable for these individuals, choosing a good fit and fabric can make a difference.

Social distancing is the best way to stay safe, but wearing a mask is key when that's not possible

O Tuathail pointed to evidence that wearing a face mask can reduce the number of virus particles emitted by as much as 99 percent, significantly reducing the risk of transmitting the disease.

"The first weapon we have in the fight against COVID is social distancing," he said. "But when we can't social distance, our seatbelt, if you want, is a mask or a face covering."

Wearing face masks has proven successful in preventing the spread of the novel coronavirus in scientific studies and real-life situations.

Two Missouri hairstylists infected with COVID-19 cut 140 clients' hair and did not spread the virus to a single customer. They were both wearing masks.

In countries where mask wearing is common, like China and Japan, coronavirus outbreaks were more modest compared to nations that weren't accustomed to the practice.