Relative Humidity and Virus Infectivity

Many researches show that maintaining a relative humidity of 40% to 60% leads to loss of infectious influenza virus from simulated coughs. 

This study looked at the role of relative humidity in the aerosol transmission of influenza in a simulated examination room containing coughing and breathing manikins.

Here is the conclusion from this research:

At low relative humidity, influenza retains maximal infectivity and inactivation of the virus at higher relative humidity occurs rapidly after coughing. Although virus carried on aerosol particles <4 µM have the potential for remaining suspended in air currents longer and traveling further distances than those on larger particles, their rapid inactivation at high humidity tempers this concern. Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus.

tldr; maintain a relative humidity of 40 to 60% to reduce virus infectivity! 

Here's another research that suggests humidity reduces virus infectivity.

relative humidity and virus infectivity

The significance of the research is as follows:

Influenza virus causes seasonal outbreaks in temperate regions, with an increase in disease and mortality in the winter months. Dry air combined with cold temperature is known to enable viral transmission. In this study, we asked whether humidity impacts the host response to influenza virus infections. Exposure of mice to low humidity conditions rendered them more susceptible to influenza disease. Mice housed in dry air had impaired mucociliary clearance, innate antiviral defense, and tissue repair function. Moreover, mice exposed to dry air were more susceptible to disease mediated by inflammasome caspases. Our study provides mechanistic insights for the seasonality of the influenza virus epidemics, whereby inhalation of dry air compromises the host’s ability to restrict influenza virus infection.


Your apartment or home humidity is normally around 20-25%. Humidifiers are a great resource to keep your relative humidity between 40-60%. All humidifiers, regardless of brand, needs to be cleaned every two to three days. Make sure to purchase a humidifier that is easy to maintain and clean! Miro humidifiers are trusted by moms all over the world for their easy-to-clean design. 

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