Maintaining relative indoor humidity at 43 percent or higher could cut the bug's threat to about 15 percent, researchers found.
John Noti and colleagues from the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, tested the effect of relative humidity on the capacity of flu virus released in a simulated 'cough' to re-infect cells.
They found that an hour after being released in a room at a relative humidity of 23 percent or less, 70-77 percent of viral particles retained their infectious capacity, but when humidity was increased to about 43 percent, only 14 percent of the virus particles were capable of infecting cells.
Most of this inactivation occurred within the first fifteen minutes of the viral particles being released in the high-humidity condition.
The study concludes that maintaining indoor relative humidity at levels greater than 40 percent can significantly reduce the infectious capacity of aerosolized flu virus.
The study was recently published in the open access journal PLOS ONE.