Joggers huffing and puffing as they run past others should wear face coverings, say scientists.

According to the Independent, experts say it’s OK to ditch the mask when running in wide, open spaces, but in crowded areas, runners should cover their nose and mouth.

“There is no doubt the virus is in the air, there’s no doubt that you can catch it if you inhale, and that someone has exhaled,” said Professor Trish Greenhalgh of Oxford University. “The exercising jogger — the puffing and panting jogger — you can actually feel their breath come and you can sometimes feel yourself inhale it, so there’s no doubt there is danger there.”

But other scientists disagree. A top infectious disease expert accused Greenhalgh of “whipping up hysteria” because forcing joggers to don masks while running outdoors would be a disproportionate response to the amount of risk they pose, according to the Daily Mail.

Dr. Jake Dunning, a top consultant in infectious diseases and emerging infections at Public Health England, says that suggesting people wear masks outdoors shifts the focus away from the real danger of indoor transmission of COVID-19.

“Forcing joggers to wear masks is totally disproportionate to any reasonable estimate of risk. Stop whipping up hysteria and anxieties,” he said. “Stop singling out outdoor runners for no good scientific reason and instead focus on avoiding the actual high-risk, indoor scenarios for transmission.”

Joggers responded animatedly to the discussion saying that running keeps them in shape and being in shape reduces the risk of COVID-19 complications. Others said that wearing a mask while exercising makes it difficult to breathe, according to the Daily Mail.

Greenhalgh countered that joggers who run on busy streets and sidewalks should be attentive to fellow pedestrians.

“When you’re out in the park, take off your mask and run freely,” she said, according to the Independent. “I’ve got a mask here and you can pull it up and down and that takes two seconds to do.”