The authors used a Bayesian regression model to collect data on the decay rates of the SARS viruses. They defined aerosols as particles less than 5 µm in size. They created aerosols using a three-jet Collison nebulizer and a Goldberg drum. The environment created is similar to that in the human respiratory tracts.
In aerosols, SARS-CoV-2 remained viable for 3 hours. The TCID50 dropped from 10^3.5 to 10^2.7 per liter of air. SARS-CoV-1 also had similar levels in aerosols. SARS-CoV-2 remained stable on plastic and stainless steel for 72 hours. SARS-CoV-1 had similar stability. But on copper, SARS-CoV-2 was viable for only 4 hours, and SARS-CoV-1 was viable for only 8 hours. On cardboard, SARS-CoV-2 was not viable after 24 hours, and SARS-CoV-1 was not viable after 8 hours (Figure 1A).
SARS-CoV-2 and SARS-CoV-1 decay in an exponential pattern. The half-lives of both viruses were a median of 1.1 to 1.2 hours in aerosols. On copper, the viruses had similar values. On cardboard, SARS-CoV-2 had a larger half-life than SARS-CoV-1. On stainless steel and plastic, both viruses had the longest half-lives compared to other environments. The half-life for SARS-CoV-2 on plastic and stainless steel is about 5.6 hours and 6.8 hours, respectively.
SARS-CoV-2 is similar to SARS-CoV-1 in terms of stability. Thus, the difference between SARS-CoV-2 and SARS-CoV-1 is likely due to other factors. Such factors include the high concentration of SARS-CoV-2 in the upper respiratory tract and the possibility of asymptomatic transmission. The results indicate that it is possible to transmit SARS-CoV-2 through aerosols or surfaces. This is because SARS-CoV-2 can remain viable in the air or on surfaces for many hours or days.