Madrid / How long does coronavirus last on surfaces? Does it behave the same in all cities? A new study says no: temperature, humidity and surface type play a role in how long it takes for virus droplets to dry after coughing or sneezing.
Respiratory viruses can be transmitted by droplets that are generated by sneezing, coughing, and even talking, and one of the many questions that researchers are trying to answer is how long the coronavirus causing covid-19 disease remains alive after someone infected coughs or sneezes.
And it is that, once the virus-carrying droplets evaporate, the residual coronavirus dies quickly, so the survival and transmission of covid-19 are directly affected by the time these droplets remain intact.
In an article published in the Physics of Fluids journal of the American Institute of Physics, researchers examined the drying time of respiratory droplets on various surfaces in six cities around the world.
Specifically, from New York, Chicago, Los Angeles, Miami, Sydney and Singapore.
The aforementioned institute of physics recalls that the size of the droplets is of the order of the width of human hair, and the researchers analyzed frequently touched surfaces, such as door knobs and touch screens of smartphones.
Drying time calculations
Using a well-established mathematical model in the field of interface science, drying time calculations showed that ambient temperature, surface type, and relative humidity play a critical role.
For example, regarding the type of surface, the study suggests that mobile screens, cotton and wood should be cleaned more often than glass and steel surfaces, because the latter are relatively hydrophilic and the droplets on them evaporate more. quickly.
In addition, according to this work, a higher ambient temperature helped dry the droplets more quickly and dramatically reduced the virus’s chances of survival.
However, in places with higher humidity, the drop remained longer on the surfaces and the chances of survival of the virus improved.
Having determined the drying time of the droplets in different climates, the scientists examined whether this was related to the growth rate of the covid-19 pandemic in the cities selected for this research.
Thus, in the places with the highest growth rate of the pandemic, the time it took for the droplets to dry was longer.
“In a way, that could explain a slow or rapid growth of infection in a particular city,” says Rajneesh Bhardwaj of the Indian Institute of Technology in Bombay, who underlines: “This may not be the only factor, but definitely Outdoor weather matters in the growth rate of the infection. ” (June 10, 2020, EFE / PracticaEspañol)
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