Researchers at the Israel Institute for Biological Research in Nes Tziona have found that the ability of the coronavirus to survive on surfaces declines the higher the surrounding temperature. Therefore, they believe that the virus will have difficulty surviving on surfaces in the conditions of the Israeli summer, and that there is no need for widespread disinfecting of public spaces. It is sufficient to maintain personal hygiene and the cleanliness of frequently used objects and surfaces, such as elevator buttons and door handles, say the researchers.
They also found that there is little risk of being infected through the air by virus particles found on a lower surface, and that there is no danger that they will spread through air conditioning systems. The findings of the study have been sent for the consideration of the national security headquarters, the Health Ministry, its Epidemiological Department and the Home Front Command.
The coronavirus is spread through droplets. This happens when a spray of tiny drops from mucus, phlegm or saliva that contain the virus penetrate the respiratory system of the person infected. However, important issues regarding the virus and its durability are still unclear: for example, how long it survives outside the body on surfaces, how environmental conditions affect it, and the minimal amount of virus that causes contagion. According to the U.S. Centers for Disease Control and Prevention (CDC), touching infected surfaces is not the primary means of transfer of the coronavirus, but it is recommended to disinfect objects that are touched frequently by many people.
In the Biological Institute study, the researchers tested the survivability of the virus on surfaces at various temperatures, a major issue in the return to the work routine and staying in shared spaces. The researchers wanted to understand the extent to which the presence of the virus on surfaces in public spaces constitutes a potential source of contagion.
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The scientists examined the durability of the virus on plastic and metal surfaces, and found that at room temperature (22 degrees centigrade or 72 degrees Fahrenheit) it survives up to four days. It was also found that the higher the surrounding temperature, the faster the virus dissipates on the surface. At a temperature of 40 degrees, for example, the virus disappeared within about three hours. At 60 degrees within 20 minutes, and at 70 degrees it dissipated entirely within 10 minutes.
In the wake of the results, the researchers believe that during Israel’s hot summer, the coronavirus won’t survive on surfaces that reach high temperatures, such as railings, metal and plastic parts in cars, and various metal installations. At the same time, they do not mention the feasibility of the virus being eliminated entirely in the summer, since this is affected by many other causes in addition to its ability to survive on surfaces.
At the Biological Institute they also tried to estimate the ability of the virus to spread in the air after landing on plastic or metal surfaces, which do not absorb it (unlike cardboard or paper). The researchers found that with routine use of surfaces and objects, the chances of the spread of the virus are relatively low.
According to the study, only deliberate shaking would cause the droplets that carry the virus to spread from the surface into the air. It was also found that there is no significant risk that the use of air conditioning would cause a renewed spreading of the virus after it has already landed on a surface.
The study indicates that the durability of the virus on surfaces is similar to that of SARS and MERS, members of the same viral family. Other Biological Institute experiments found that MERS and SARS viruses can be found after two to six days on plastic surfaces, up to two days on paper, cotton smocks and disposable smocks, and at least one day on metal and glass surfaces.