Doctors now urge people not to wear face masks while running, as covering the mouth and nose can impede breathing.

The Sun reports a man suffered a burst lung after running for miles wearing a face mask to protect against coronavirus.

The jogger, from China, was rushed to hospital after his lung collapsed following a 2.5-mile run in Wuhan while wearing a face covering, forcing him to undergo major surgery after developing the potentially life-threatening condition.

The UK Government this week advised that face masks should be used when on public transport or in shops where remaining two metres from others is difficult.

However, their guidance says: "They do not need to be worn outdoors, while exercising...or those who may have problems breathing while wearing a face covering."

The Sun quoted GP and Clinical Director of Dr. Sarah Jarvis as saying: "There is little or nothing to be gained from wearing a face mask outdoors unless you are in very close contact with other people.

"Standard face coverings (as opposed to formal personal protective equipment used by health care and other key workers, which the public shouldn’t be using) don’t protect you against the virus.

"The vast majority of air you breathe in goes round the sides and face coverings don’t filter out the virus.

"The reason they’ve been recommended in those indoor settings is because they may reduce the risk of you passing the virus on to others you’re in close contact with, if you’re infected but don’t yet have symptoms."

Meanwhile, U.S. Surgeon General VADM Jerome M. Adams has issued seemingly contradictory messages regarding mask efficacy in general, in February tweeting "Seriously people - STOP BUYING MASKS!

"They are NOT effective in preventing general public from catching Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!" (emphasis the U.S. Surgeon General's)

After more recently tweeting "Don't forget your face covering if you plan to be out in public this Memorial Day Weekend" the Surgeon General faced requests for clarification, prompting him the next day to tweet "On masks, I’ve always advised on best current science - never politics. Some feel it’s political/ infringes on their rights when told they MUST wear one.

"I’m ASKING based on current CDC recommendations, that you CHOOSE to wear a mask in public, to protect the vulnerable."

However, the Surgeon General did not issue a retraction as unequivocal as his earlier declaration of mask ineffectiveness to prevent contagion.