(CNN)A doctor in England wanted to prove that face masks won't impair your oxygen levels. So he ran for 22 miles while wearing one.
Throughout his running journey, Tom Lawton used a pulse oximeter to monitor his oxygen levels. The medical device measures the saturation of oxygen in a person's red blood cells and typically clips to your finger.
"The mask didn't come off at all (no food or drink) -- and oxygen levels were stubbornly 98% every time I checked," he tweeted last month.
In an on air interview with CNN Sunday morning, the ICU doctor said he wanted to show everyone that masks are safe to wear and are a necessity in curbing the spread of the coronavirus.
Health officials urge people to wear a mask not only for themselves but to protect others. This guidance has been met with controversy over the past few months as people are refusing to wear them.
"I was frustrated because I've seen some photos where people who sat at a desk wearing a mask and claimed that the oxygen levels dropped just simply wearing a mask," Lawton said.
Duly inspired, Lawton donned his three-layered cloth mask one day and then ran 8 miles to work while monitoring his oxygen levels. After work, he ran another 14 miles. While he does admit the mask was rather uncomfortable, he says his oxygen levels never dropped.
"I don't think that masks are going to solve this on their own," Lawton said. "We need to keep distance, comply with isolation, wash hands and wear a mask."