Now that we can go out and there are more people around, is it safe to take a walk or hang out in the park? The risk of infection is low, as long as you follow some rules
Today in Italy the shops have reopened and a good part of the production activities have been restarted , after about two months of restrictions made necessary to slow down the spread of the coronavirus pandemic. The reopenings will involve some more risks: in addition to having brought some controversy on the usefulness of removing almost all the limitations, many are wondering if with the possibility of returning to come out more assiduously there are higher and more concrete risks of being infected.
Over five months of pandemic have taught us that coronavirus is spread mostly through the tiny droplets that infected people emit by coughing, sneezing, talking and even breathing during an effort (for example while running) . The largest droplets remain in the air for a very short time and fall on the surfaces, where according to some studies the virus can resist for a few hours and up to a maximum of two to three days. The smaller saliva drops may instead remain in suspension for several minutes, but according to the researchers this does not involve particular risks, especially if you are outdoors.
In the open air, coronavirus particles (virions) emitted with droplets are rapidly diluted in the air, which reduces the possibility of breathing in such quantities that they are dangerous. A single virion is not enough to cause an infection and is easily destroyed by the immune system before it can do harm. Research on the amount beyond which coronavirus virions can cause an infection is not yet definitive, but still estimates from a few hundred to several thousand individual viral particles within short exposure times.
A rather contagious person can emit droplets containing up to 200 million viral particles with a sneeze. In a closed environment with low air exchange it could prove risky for people who share the same space, while the risks are enormously lower in the open air where even significant quantities of virions are rapidly diluted.
Wind and contagions
Many fear that a gust of wind can carry droplets emitted by a cough or a sneeze for several meters, with the real risk of infecting someone who had kept at a safe distance. In fact, the wind tends to disperse droplets and significantly reduce their concentration, therefore with a low risk of being infected.
Scientific evidence on contagions in the open air is currently sporadic, although not to be underestimated. A study carried out in China with the analysis of 7,300 coronavirus positive cases found that in one case the infection had occurred outdoors. A 27-year-old man had a conversation with an acquaintance who recently returned from Wuhan, the Chinese city where the pandemic started. After seven days he had experienced the first symptoms of COVID-19 and a subsequent examination had confirmed coronavirus positivity.
As several experts explained to the New York Times , the Chinese study reminds us that the risk is lower outdoors than indoors, but it is still not zero. There may be special circumstances, for example a person who remains for a long time and without adequate protection in close contact with an infectious individual. On the other hand, it seems more unlikely that the transmission could take place between two people who cross each other on the street passing close by.
While doing physical activity you breathe out larger quantities of air and this increases the probability that a contagious diffuses more virions in the surrounding environment. Again, however, the researchers believe that there are no particular risks in passing close by or being overcome by people who run, ride a bicycle or are engaged in a brisk walk. The time in which one remains close is very low and constitutes a limited risk.
Swimming pools and the sea
There is still no clear and certain evidence on the risks of contagion in particular outdoor places, which with the approach of summer will be more and more popular, such as swimming pools, lakes and bathing establishments. From current knowledge and from those on other viruses, contagion through water appears unlikely, due to the great dilution that viral particles would suffer. Contagion could however be possible if there was particular crowding at the poolside, along the shore or even in the water between several people.
Restaurants and meeting places
In restaurants, even with outdoor tables, there may be some more complications due to the greater permanence of people and coming into contact with many objects that could be contaminated. The advice is to visit only places that guarantee a correct distance between the tables and to do it only with the people with whom you already live, and with whom a sort of isolated bubble is formed.
The same rule should also apply to meetings between friends, which in Italy can take place outdoors as long as they do not create a crowd and with respect for the distance and the protections. Even in private gatherings, initiatives shared with people with whom you already share the same spaces should be privileged, limiting the others to a few friends, forming a stable group in which contacts with external members are minimized.
The most important rule to apply, however, remains that of physical spacing, keeping at least one meter away from the next. It is a sufficient measure to greatly reduce the risk of contagion in outdoor places. If you are not sure if you can easily keep the meter away, it is advisable to wear a mask, which can help reduce the spread of droplets with the risks involved.