The Importance Of Humidity and Diffusion In Protecting Against Transmission of the Flu

photo credit: unknown

(This information is provided by my friend Doug Corrigan)

Did you know that the reason flu is transmitted more prevalently in the winter months has nothing to do with the fact that it’s cold outside?

The reason the flu and other cold-like viruses are transmitted in the winter months is due to the low humidity conditions during those months. Multiple research studies conducted by the the CDC and other research universities have demonstrated that the influenza virus is transmitted as an aerosol much more readily in air that is devoid of moisture. Because the winter months tend to exhibit the driest air, both outdoors and indoors, the transmission rate of the flu virus skyrockets as it can survive passage through the air in droplets.

For example, the research study by John Noti with the CDC demonstrated that at 43 percent relative humidity, only 14 percent of the virus particles that were released were able to transmit the influenza virus. This is in contrast to the 70 percent transmission rate in air that is at 23% relative humidity. Also, the protective effect at higher humidity levels appeared to be rapid, with the majority of viral inactivation taking place within 15 minutes of when viral particles were first “coughed” into a high-humidity environment.

This just underscores the importance of running a large humidifier in your house during the winter months. Diffusers can’t replace a humidifier, but you can use diffusers in various rooms to supplement this effect, especially close to your bed at night while you are sleeping.

————> A few research studies are referenced below:

Noti, John D., et al. “High humidity leads to loss of infectious influenza virus from simulated coughs.” PLoS One 8.2 (2013): e57485.

Lowen, Anice C., and John Steel. “Roles of humidity and temperature in shaping influenza seasonality.” Journal of virology 88.14 (2014): 7692-7695.

Jaakkola, Kari, et al. “Decline in temperature and humidity increases the occurrence of influenza in cold climate.” Environmental Health 13.1 (2014): 22


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