Is wearing a mask outdoors effective against Covid-19? What do scientists say?

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Is wearing a mask outdoors effective against Covid-19?  What do scientists say?


Does wearing a mask outdoors reduce coronavirus transmission or is it a futile endeavor? The prestigious medical journal BMJ quoted the theses of scientists from two views.

“Wearing a mask in the open air should be the rule because it can both reduce the transmission of SARS-CoV-2 and encourage wearing masks indoors where the risk is higher” or “The outdoor transmission rate is so small in the general spread of the virus that it can be Focusing on wearing will give much more meaningful results in terms of combating the epidemic “. Both are advocated by leading scientists.

The respected international medical journal BMJ (British Medical Journal) published in the UK this week, defending both views. you He discussed health professionals and brought together what is known about the different dimensions of the issue.

Those who say masks are useful outside: Babak Javid, Dirk Bassler, Manuel B Bryant tell

The possibility of transmission of the coronavirus indoors is much higher than the possibility of transmission outdoors.

But we think that the mask should be worn outside under certain conditions. Let’s explain:

First of all, let’s emphasize that we do not advocate that the risk of contamination is large outdoors.

In addition, we are not in favor of obliging to wear a mask in all conditions outdoors. When a person is alone or with someone who lives in the same household, they do not have to go out in a mask in the open air.

But we advocate a nuanced approach to wearing a mask that takes details and different conditions into account.

Different estimates are made in terms of the difference in contamination risk in open air and indoors. We think that the risk of transmission in closed areas is at least 4 to 20 times higher than in outdoor places.

The risk of coronavirus transmission probably depends on the amount of infected particles in the air. Here, the density of these particles at a given moment and how long the person was exposed to it is important.

In situations with low airflow (windless and motionless), people carrying the virus will be close to other people while waiting in crowds or in queues, creating a transmission risk, although not as much as in a closed area.

Are there any examples of super spread outdoors?

In addition, it was observed that people working in some outdoor jobs, such as agricultural workers, had a seriously high risk of getting Covid. But a closer look revealed that the risk might be due to cramped dormitory conditions rather than working together in the open air.

It was understood that some of the activities, which are called super-spreading events, that led to the rapid spread of the epidemic, were mostly, but not completely, indoor activities.

For example, massive Black Lives Are Valuable shows were held in many parts of the world in the summer of 2020. At the time, experts warned that these protests could accelerate the spread of Covid-19, but these fears did not materialize.

But the opposite also happened. For example, the Sturgis Motorcycle Rally, held in South Dakota in the USA, is thought to be a huge super-spreading environment and played an important role in the growth of the epidemic.

One of the possible reasons for this is thought to be the lack of attention to social distance and the majority of not wearing masks. Observational data also indicate that those coming from regions where mask and social distance bans are more strictly enforced are more careful than those coming from regions where these issues are underestimated.

In summary, we believe that it is difficult to keep the physical distance in the air for a long time. Sport We think that wearing a mask during large outdoor events such as events such as meetings will reduce the risk of Covid-19 during the epidemic period in two ways: In terms of both reducing the risk of contamination, even if it is low, and the normalizing effect of wearing a mask in general.

Those who say there is no need for a mask outside: Müge Cevik, Zeynep Tüfekci, Stefan Baral talk

The risk of coronavirus transmission in the open air is significantly lower than indoors. Less than 10 percent of Covid-19 cases appear to be transmitted outdoors, and these are mostly among people who come to beer both indoors and indoors and who have been physically close for a long time. Moreover, no single outdoor event has ever been proven to be super-spreading.

The Sturgis Motorcycle Rally in South Dakota or the invitation to the White House’s Rose Garden are often cited as examples of outdoor super-spreader events, but these are long-term and partly indoor events. For example, the examination of the Sturgis Rally for the epidemic revealed that many cases that spread from here originated from restaurants or offices.

In the open air, due to the low virus density thanks to natural air movements, the outdoor contamination effect of the Covid-19 epidemic is very low.

Regular use of masks outdoors is often emphasized as an easy-to-apply measure, and this is also supported by the principle of preemptiveness.

However, using the preventative principle in place requires an observational evaluation of benefits and costs.

In addition, while leaving a year behind the Covid-19 epidemic, the principle of prevention cannot be put forward as if there is no data on transmission routes and risk intensity.

Finally, the cost of policies aimed at regularly using masks outdoors must be balanced with their limited benefits.

Personal and systemic costs

Public health interventions depend not on habits, but on people’s trust in political decision-makers and on a transparent dialogue with the public.

Given the low risk of transmission in the open air, the recommendation or obligation to wear a mask outside will be controversial and will reduce the trust of people, reducing the impact of interventions on more important issues such as using masks indoors or staying home when sick.

Regular use of masks in the open air can also distract the attention of the public from the measures to be taken indoors with much higher risk and may distort the relative risk perception.

Therefore, scientific data about the mechanisms of transmission should be explained to the public, and they should be encouraged to be careful mostly indoors, and attention should be paid to the risks of close distance for a long time outside.

Social isolation is a factor that increases deaths and premature deaths and plays a much more important role in health than is often thought.

Restrictions imposed due to the epidemic have already limited social relations and reduced morale. In addition, if the necessity of a mask outside is imposed, this can play a deterrent role and increase the isolation even more. It may cause people to tend to meet indoors or to give up sports activities in the open air, which play an important role in both body and mental health.

Therefore, spending energy mostly on the prevention of indoor contamination and keeping the open air as a place where people can recharge energy and maintain their social relations will provide great benefits for public health.

From a system perspective, all interventions have a cost.

The cost of applying the mask requirement outside means not using opportunities to carry out more effective policies or projects in other areas.

Finally, the necessity to mask outside may be popular in some cases as the most visible intervention indicating decisive leadership. However, such mandatory measures are not effective in reducing the risk of transmission or solving the problems arising from the socio-economic inequalities and structural racism raised by the epidemic, and they contribute to the spread of cases and the continuation of inequalities observed in every corner of the world.

BBC


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