Humidity lessens spread of flu, study finds

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Winter may seem like a desolate, lifeless season for most living creatures, but for the influenza virus, it's a time to thrive. Recent research explains that dryness in the air caused by cold weather and indoor heating creates near perfect conditions for the virus to spread and survive.

For many years, scientists have studied the correlation between air's relative humidity and the ability of the flu virus to survive and spread. While a 2007 study did find some relation, the connection was not very strong. Researchers at Oregon State University recently went back and looked at the data again, only this time, they focused on air's absolute humidity. The flu remains a persistent threat to nursing homes and nursing home residents.

Absolute humidity is the actual amount of water in the air. Low absolute humidity can explain 50% of viral transfers and up to 90% of the virus' survivability, say researchers. More moisture in the air means less chance for the flu virus to survive. This research lends credence to the idea that cranking up the humidity in nursing homes and hospitals could help reduce the rate of infection during flu season, though they point out that further research is needed to confirm these findings. Their report appears in Tuesday's issue of Proceedings of the National Academy of Science.