Understanding the Duration of the Coronavirus on Surfaces and in the Air

Introduction

Understanding how long the coronavirus can survive on surfaces and in the air is crucial for effective infection prevention and control measures. This article delves into the findings from various scientific studies, aiming to provide a comprehensive understanding of the virus’s behavior under different conditions.

Survival on Surfaces

No clear answer exists regarding the exact duration the coronavirus can remain active on surfaces. In many instances, the virus may survive for less than an hour, particularly in non-ideal conditions. However, under specific circumstances, it has been observed that the virus can potentially remain active for several days.

According to a study conducted by the National Institutes of Health (NIH), the coronavirus (SARS-CoV-2) can survive for hours to days when sprayed from water. The results indicate that the virus can persist for at least two hours in the air. Moreover, it can survive:

Three hours on copper One day on cardboard 3-4 days on steel or plastic Seven days on N95 masks

Some recent studies have utilized a different virus model to simulate the viral behavior on surfaces. These studies suggest that the survival time can be significantly shorter, with the virus becoming non-infectious within minutes after the deposit dries. The authors attribute this shorter survival time to the mucins in the saliva, which can essentially "glue" the virus into a passive form, rendering fomites less of a significant source of infection.

Aerosol Behavior

Aerosols are the primary route of infection for the coronavirus. When saliva aerosols are sprayed, they tend to dry very quickly to particles. These particles likely remain infectious as long as they are inhaled. The mucin binding effect that preserves the virus on surfaces is effectively undone when the aerosols enter the nasal passages, where the particles dissolve.

It is important to note that neither the NIH tests nor the mucin tests were conducted with real SARS-CoV-2 or saliva/snot as carriers. As such, the findings are not definitive and should be interpreted with caution.

Other Virus Models

Other research has used a different virus model derived from cow saliva to simulate the behavior of the coronavirus on various surfaces. These studies have found that the survival time is much shorter on surfaces, typically within minutes of the deposit drying.

Saliva aerosols, on the other hand, dry even more quickly due to the fine nature of the particles and their high surface area. Therefore, once the aerosol particles dry, the threat persists if inhaled.

Duration in the Air

The duration of the coronavirus in the air is also a critical consideration. Based on observations, the virus dissipates rapidly, often disappearing from the entry door to the dining table within about 30 seconds to one minute. This rapid dissipation is attributed to the physical properties of aerosols, which tend to settle quickly due to gravity.

A qualitative experiment involving the throwing of droplets into the air provides an interesting insight. Droplets were observed to stay in the air for only a few seconds before landing due to gravity. This experiment reinforces the notion that the virus does not remain airborne for extended periods, making aerosol transmission particularly challenging to control.

Conclusion

Survival times for the coronavirus on surfaces and in the air vary widely depending on the study and conditions. While some studies suggest longer survivability, the rapid dissipation of the virus in the air makes fomites a less significant source of infection. However, aerosols pose a persistent threat, especially when inhaled. As new research continues to emerge, it is essential to stay informed and adapt preventive measures accordingly.

Note: This article does not provide a definitive answer due to the variability of findings from different studies.