Humidity and Spread of Coronavirus
- 31 Mar 2020
- 2 min read
Why in News
Recently, a study by researchers at the Massachusetts Institute of Technology (MIT) in the United States found that regions experiencing a monsoon might see a slowdown (not a stop) in transmission of the coronavirus as a result of moderate levels of humidity.
- This could help mitigation strategies in tropical countries such as India.
- The findings show that 90% of the novel coronavirus transmissions have occurred in regions with temperatures between 3 and 17 degrees Celsius.
- These regions also had an average humidity range of 3-9 gram per cubic metre (g/m3).
- These regions comprised the United States and several European countries that are inundated by COVID-19 infections.
- There are comparatively fewer infections in warmer and humid countries such as Singapore, Australia, Taiwan and Qatar.
- It is also possible that warmer temperatures retarded the spread of the virus.
- A series of experimental studies have shown that the Coronaviruses are sensitive to humidity and are less likely to thrive at moderate levels of humidity.
- A 2018 study in the peer-reviewed Applied and Environmental Microbiology concluded that
- Coronaviruses thrived when the Relative Humidity (RH) (the proportion of water vapour in the air compared to what’s the maximum possible) exceeded 85% or dipped below 60%.
- There is a significant decrease in infectivity at mid-range RHs (60 to 85%).
- A similar experiment that tested the ability of viruses to survive on stainless steel surfaces, found that :
- At 4°C, infectious viruses persisted for as long as 28 days.
- The lowest level of inactivation occurred at 20% RH.
- Inactivation was quicker at 20°C than at 4°C at all humidity levels.
- The slowest inactivation occurred at low levels of RH.