Higher humidity takes toll on flu virus

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Residents who want a room humid should be obliged because higher humidity levels can significantly reduce the infectiousness of influenza virus particles released by coughing, research shows.

Investigators at the National Institute for Occupational Safety and Health and the Centers for Disease Control and Prevention tested the effect of relative humidity on the flu virus. They discovered when humidity in a room was increased to about 43%, only 14% of the virus particles were capable of infecting cells. The study team was led by John Noti, Ph.D. 

In addition to long-term care residents, healthcare workers are particularly susceptible to flu infection. 

The study, published Feb. 27 in the journal PLOS One, recommends keeping indoor relative humidity at levels greater than 40% to reduce flu virus infectiousness.

Raising the humidity levels “may not be practical, given design limitations built into the facilities,” the authors wrote. “However, if functional areas of healthcare facilities were identified as high-risk for flu transmission ... consideration could be given during the design and construction phase of these facilities to accommodate maintaining appropriate recommended humidity levels.”