DHS Science and Technology

Factors Affecting the Stability of SARSCoV-2 on Surfaces

PROBLEM ADDRESSED

While most data suggest that droplets or aerosols are the predominant 

modes for SARS-CoV-2 transmission, infection may also occur after 

touching contaminated surfaces and transferring virus to the nose, mouth 

or eyes. As a result, elevated hygiene and disinfection practices are in place 

to mitigate the potential for such contact transmission. At the onset of the 

pandemic, it was shown that SARS-CoV-2, the virus that causes COVID19, could remain infectious on surfaces for several days under a limited set 

of environmental conditions. However, the effects of a wide range of 

environmental conditions (e.g., temperature, relative humidity, and 

sunlight), droplet size, and surface type on how long the virus survives on 

surfaces were largely unknown. To better understand the stability of SARSCoV-2 on surfaces and to inform the potential for contact transmission, 

NBACC conducted a series of studies to identify the environmental factors 

that influence how long infectious SARS-CoV-2 remains on nonporous 

surfaces. 

KEY RESULTS

• Temperature, relative humidity, and simulated sunlight all affect how 

long SARS-CoV-2 remains infectious on surfaces, with simulated 

sunlight causing the most rapid decrease in infectivity.

• Under conditions representative of indoor climate-controlled

environments, virus remained infectious for several days with the time 

required to kill 90% of the virus under cool dry conditions being 

approximately 51 hours.

• In the absence of simulated sunlight, increasing temperature and/or 

relative humidity resulted in faster inactivation of virus on surfaces.

• SARS-CoV-2 infectivity decayed rapidly in the presence of simulated 

sunlight and was dependent on solar intensity. The time required to kill 

90% of virus at peak summer solar intensity was 6.8 minutes.

• Decay was not different among three different droplet sizes tested, nor 

did the type of nonporous surface (stainless steel, ABS plastic, nitrile 

rubber) onto which the virus was deposited affect its stability.

• Using these data, a mathematical model was developed to allow a 

user to predict how long SARS-CoV-2 will remain infectious on indoor 

 

surfaces under different environmental conditions.

SIGNIFICANCE OF RESULTS

These results suggest that nonporous surfaces contaminated with 

SARS-CoV-2 may remain infectious for several days under 

environmental conditions commonly encountered in climatecontrolled indoor environments. Consequently, the data suggests that 

contact transmission may be possible, even though current 

epidemiological data still point to droplet and aerosol exposure as the 

primary means of infection. Reduction of potential exposure to 

contaminated fomites indoors is best mitigated by more frequent

cleaning and disinfection of high-touch surfaces, and regular hand 

washing. Because the potential for encountering infectious virus on 

surfaces is higher indoors than outdoors, it is also recommended that 

operations be moved outdoors when possible in addition to employing 

social distancing and the use of PPE for at-risk individuals. 

While increasing temperature and humidity resulted in increased 

decay of infectious virus on surfaces, this effect would not sufficiently 

reduce virus infectivity in an operationally relevant time frame that 

would significantly decrease the potential for exposure. Therefore, 

these results do not support increasing the temperature and relative 

humidity of inhabited permanent structures or environments. 

However, when vacating or re-using a temporary structure that 

housed infected individuals (e.g., a mobile support tent or trailer), 

actively increasing temperature and relative humidity (e.g., 95° F and 

60% RH) for several days prior to normal cleaning and disinfection 

practices would have complementary effects by reducing potential 

exposure to infectious virus, particularly for contaminated hard to 

reach areas where manual cleaning would be difficult.

Finally, because these results suggest that sunlight rapidly inactivates 

infectious SARS-CoV-2 on surfaces, placing potentially contaminated 

nonporous objects (e.g., shopping carts, baskets, folding chairs) 

outdoors and in direct sunlight in addition to normal disinfection and 

cleaning may further reduce the potential for transmission of the virus 

from these contaminated surfaces.

The predictive model developed using droplet deposited virus decay 

data from this study allows a user to estimate the persistence of 

SARS-CoV-2 on nonporous indoor surfaces across a range of 

environmental conditions (74-95 °F and 20-60% RH). This tool can 

be found at: https://www.dhs.gov/science-and-technology/sarscalculator. 

REFERENCES

Ratnesar-Shumate et al. Simulated Sunlight Rapidly Inactivates 

SARS-CoV-2 on Surfaces. 

J Infect Dis. 2020 Jun 29;222(2):214-222.

Biryukov et al. Increasing Temperature and Relative Humidity 

Accelerates Inactivation of SARS-CoV-2 on Surfaces. 

mSphere. 2020 Jul 1;5(4):e00441-20.

Contact Us: PANTHR@hq.dhs.gov scitech.dhs.gov dhsscitech 

20 20 - 01