Many pedestrians or cyclists travel through major American cities wearing masks, even when they are far from each other.
Some US states, such as Maine, continue to require masks to be worn on hiking trails and on beaches.
Experts are debating the question of the utility of such measures.
Scientists have learned a lot about COVID-19 since the start of the pandemic.
They now know that surfaces do not play a large role in virus transmission and that excessive disinfection is a waste of time and resources.
On the other hand, many experts believe that the disease is transmitted from the air. It is spread primarily by fine particles that remain suspended in the air for a certain period of time, not by droplets from a cough or sneeze, which fall rapidly to the ground.
This is why being outdoors is safer than indoors, says Jose Luis Jimenez, an aerosol expert and professor at the University of Colorado Boulder.
He explained to France Press that “being inside is much more dangerous because the walls, ceiling and floor trap air,” especially in the case of poor ventilation. “The outdoors is much less dangerous because there is more air in motion” and the air we breathe rises, especially when the weather is hot.
This does not mean that there are no risks, he adds. In the same way that you would likely inhale some smoke from your neighbor’s cigarette who smokes outside, it is possible for you to contaminate the COVID-19 virus if you stay away for a long time, near an infected person, even outside.
There are now many studies on the dangers of pollution abroad. Last October, Chinese researchers published an investigation in the journal Indoor Air, gathering information on 7,324 cases, including where the virus was transmitted.
Of more than 7,000 cases, only one was related to overseas transmission: a 27-year-old villager was infected in January 2020 after an overseas conversation with an infected person, near Shangqiu, in central Henan province.
Recently, the Irish Times asked Irish health authorities how many cases were overseas out of 232,164 in the country as of March 24, 2021. The response was 262, or just 0.1% of the total.
This estimate may be overestimated, given that authorities relied on unverified information from outside activities – such as a construction job or playing sports – but some of the people involved may also have been able to rely on them to participate in rallies indoors.
Donald Milton, a professor at the University of Maryland and a pioneer in aerosol science, advises avoiding crowds outside, especially when shouting or singing as planned at a game, concert or event, and when there is no wind.
But he doesn’t think wearing a mask all the time outside is necessary.
“When I jog in my neighborhood, where houses are at least 10 meters away, and there are only a few people walking their dogs and children playing in the gardens, I keep my mask in my pocket,” he says.
“I can’t run for a long time wearing my mask,” he explains. “If I stop talking to people, I can wear it. If I walk with friends, I wear it.”
Wearing a mask has become a highly politicized issue in the United States, with conservatives, under Donald Trump, seeing it as an affront to their individual freedom.
Progressives generally take the virus more seriously and see the mask as a way to show solidarity with their neighbors in times of crisis.
But for Amesh Adalja, a public health expert at Johns Hopkins University, it is time to scrap the outdoor mask requirement and take a more nuanced and science-based approach.
“The masks have been so politicized that some people denounce other individuals for embarrassing them,” he laments. “I think it is counterproductive.”
“What we want is for people, especially those who have not been vaccinated, to wear a mask when they are inside and cannot respect social distancing,” the expert explains.
He says giving the impression that being outside is dangerous might cause people to congregate inside, which is worse.
Some experts argue that the advantage of making the wearing of the mask mandatory abroad is that it simplifies the message to the public, which Amesh Adalja objects to.
“The only result is that the public has less confidence in the health authorities,” he said, noting that the public is able to read medical journals and realize that public discourse differs from scientific data.