With the spread of SARS-CoV-2, people are very conscious not to touch any surface that might be contaminated with virus. Opening doors with your knees is an example of this behavior.
There are two known ways of spread of the virus. One is by respiratory droplets of the patient. When a COVID-19 patient coughs or sneezes, droplets are spread in air. These droplets reach nearby surfaces and smaller droplets stay in the air.
A nearby person can also get virus if they reach mouth or nose of the person. The reason experts are advising to use to use three-layer masks is to stop the droplets reaching nose or mouth.
The second way is by touching contaminated surfaces and then touching face or mouth. Many surfaces like doorknobs and other things which are used by public can have virus on them. It can reach our nose and mouth and then inside through our hand.
Health experts have warned people not to touch their face if they are outside. If it is necessary, use hand sanitizer first and then touch your face.
The first way is more susceptible, however, second way is an unnoticed threat. One can stay away from other persons or people who have virus and isolate themselves but we can’t find whether a surface is contaminated or not.
Scientists expect that hot weather can stop the spread of the virus by contaminated surface. If it can’t be stopped, at least spread would be slower. At high temperature, the life of virus would be lower and it will not be able to survive for long time out of the body, on any type of surface.
A study performed recently says that survival of the virus depends on droplets drying time which depends on size of the droplet, type of surface and temperature.
Study author, Rajneesh Bhardwaj, PhD, and associate professor at the Indian Institute of Technology in Mumbai, said “motivated by [the] ongoing COVID-19 pandemic, we conducted this research to understand the drying of respiratory droplets deposited on a surface because we know COVID-19 spreads through these droplets.”
The team analyzed the drying time of the droplet under different conditions. The research was performed in six cities: New York, Chicago, Los Angeles, Miami, Sydney, and Singapore. It was found that cities which had higher number of cases had longer survival time of droplet, or we can say longer droplet survival time causes higher number of cases.
Study found that the SARS-CoV-2 stays on a surface for 5 times longer in humid conditions as compared to dry areas. Additionally, it was seen that higher temperature kills the virus quickly.
The study author wrote, “this can be illustrated by comparing the drying time of Singapore and New York City. The time is shorter for the former as compared to the latter, despite with a large humidity for the former (70–80 percent) as compared to the latter (50–60 percent).”
The risk of spread is lower but higher temperature can not eliminate the virus completely.