Coronavirus survives longer on glass, plastic than cloth, paper: Study
The novel coronavirus may survive for a far lesser time on porous surfaces such as paper and clothes than on impermeable surfaces like glass and plastic, a Indian Institute of Technology (IIT) Bombay study suggests. COVID-19, caused by the SARS-CoV-2 virus is transmitted through respiratory droplets that form the fomite upon falling on a surface, which serves as a source for infection spread.
Researchers analyzed state of droplets on impermeable and porous surfaces
In the study, published in Physics of Fluids, the researchers analyzed the drying of droplets on impermeable and porous surfaces. They found that a droplet remains liquid for a much shorter time on a porous surface, making it less favorable for the virus' survival.
Figures about survival of virus on different surfaces
The research suggests that the virus can survive for four days on glass, and seven days on plastic and stainless steel. However, the virus survived for only three hours and two days on paper and cloth, respectively, the researchers said. The study also suggests that seats in public places could be covered with cloth to reduce the risk of disease spread.
Suggestions made for use of cloth in public places
"Based on our study, we recommend that furniture in hospitals and offices, made of impermeable material, such as glass, or stainless steel, be covered with porous material, such as cloth, to reduce the infection risk upon touch," said Sanghamitro Chatterjee, study author, from IIT Bombay.
Virus can stay on surfaces after liquid evaporates
According to the researchers, 99.9 percent of the droplet's liquid content for both impermeable and porous surfaces is evaporated within the first few minutes. However, they noted that after this initial state, a microscopic thin residual liquid film remains on the exposed solid parts, where the virus can still survive.
Evaporation of thin film much faster in porous surfaces
Another IIT Bombay team including Janani Srree Murallidharan, Amit Agrawal, and Rajneesh Bhardwaj, discovered the evaporation of this remnant thin film is much faster in porous surfaces than impermeable surfaces. "The droplets spread due to capillary action between the liquid near the contact line and the horizontally-oriented fibers on a porous surface and the void spaces in porous materials, which accelerates evaporation," they said.
Findings might prove relevant for specific fields
"The fact that just the geometric features rather than the chemical details of the porous material make the thin film's lifetime significantly less was surprising," Bhardwaj explained. The researchers said that the study findings, such as the droplet's liquid phase lifetime of approximately six hours on paper, will be particularly relevant in certain contexts, like schools.
Liquid phase lifetime can help frame safety measures for schools
The researchers said, "While this timescale is shorter than that of any permeable material, such as glass with a liquid phase lifetime of around four days, it would impact the exchange of notebooks." The researchers said that it could come in handy when policymakers evaluate safe measures for reopening schools or the exchange of currency note transactions in retail banks.
