According to a new study, the virus responsible for Covid-19 can remain infectious on most of the surfaces for several days as it transforms itself into a microscopic pancake-like film after the water content in the particle has evaporated.
The researchers have also noted that the conversion sees more than 99.9 percent of the droplet’s liquid content vanish within a span of a few minutes, however, the virus still thrives in a protective film of the remaining fluid. They have ascertained that the nanometres thick film slows down the evaporation process.
Their studies also revealed that the film fully evaporates at different times and it depends on the material of the surface it has landed on. In their experiments, they found that a large droplet on stainless steel and copper lasted 24 and 16 hours respectively.
While it survived for more than 150 hours on polypropylene surfaces and a small droplet one-tenth of its size could last more than 80 hours on the glass.
These figures were based on experiments conducted in protective lab conditions and are likely to be lower in the real world. As the varied temperature and airflow factors may boost the evaporation process.
Professors at the Indian Institute of Technology (IIT) Bombay – Rajneesh Bharadwaj and Amit Agarwal used computer modelling and advanced physics applications to understand how the virus droplets can spread the disease.
They had previously found that wearing a face mask reduces the size of the clouds of the infectious coronavirus particles generated by a cough by up to 23 times.
According to the data published by the Physics of Fluids, the thickness of the film decreases gradually and throughout this duration, the amount of coronavirus in the droplet-film remains intact.
“It is desirable to disinfect frequently touched surfaces, such as door handles or hand-held devices, and within hospitals and other areas prone to outbreaks," said Prof Agrawal.
“Our biggest surprise was that the drying time of the nanometric film is on the order of hours," Prof Bharadwaj added.
The researchers said that their study showed the virus can survive in a potent form for long durations and stressed the need for regular and thorough cleaning of surfaces.