Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification

[mixin]

Background
Laboratory research studies indicate that aerosolized influenza viruses survive for longer periods at low relative humidity (RH) conditions. Further analysis has shown that absolute humidity (AH) may be an improved predictor of virus survival in the environment. Maintaining airborne moisture levels that reduce survival of the virus in the air and on surfaces could be another tool for managing public health risks of influenza.

Conclusion
This modeling analysis demonstrates the potential benefit of portable residential humidifiers in reducing the survival of aerosolized influenza virus by controlling humidity indoors.

Environmental Health 2010, 9:55 doi:10.1186/1476-069X-9-55
Theodore A Myatt (tmyatT@eheinc.com)
Matthew H Kaufman (mkaufman@eheinc.com)
Joseph G Allen (jallen@eheinc.com)
David L Macintosh (dmacintosh@eheinc.com)
M PATRICIA Fabian (pfabian@hsph.harvard.edu)
James J McDevitt (jmcdevitt@hsph.harvard.edu)
Full .pdf http://www.ehjournal.net/content/pdf/1476-069x-9-55.pdf

[Laidback Al]

Re: Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification

The full article is dense reading. Some significant passages are presented below. The bottom line is that there is a decrease in indoor influenza virus survival when the relative humidity is between 40 and 60%.

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<o:p></o:p>
Increasing low indoor moisture levels may have benefits beyond reducing survival of the <o:p></o:p>influenza virus. Low RH has been associated with a number of symptoms including dry skin, throat and mucous membranes and eye irritation in office and hospital workers [33-35]. In a home humidification intervention, the authors reported a decrease in dryness of the nose and throat and improved breathing in patients with allergies [36].
<o:p> </o:p>
While there are apparent benefits to residential humidification for control of influenza virus in the air and on surfaces and temporary relief from cough and cold symptoms, excessive indoor humidity can lead to unattended consequences such as mold and mildew growth [37]. . . .
<o:p> </o:p>
There is data, however, that indicates that increased humidification decreases survival of influenza virus on surfaces [40-42]. Therefore, while the focus of our modeling effort was on airborne influenza virus, humidification may reduce survival of the virus on household surfaces. . . .
<o:p></o:p>
Our results build upon previous efforts to evaluate the impacts of moisture on influenza virus survival [2-9, 13, 47]. These laboratory studies have consistently confirmed that survival of the influenza virus in the air and on surfaces is modulated by moisture levels, with the majority showing the lowest level of survival in the range of 40 to 60% RH.<o:p></o:p>
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[mixin]

Re: Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification

These laboratory studies have consistently confirmed that survival of the influenza virus ... on surfaces is modulated by moisture levels,

I don't understand why that is. I would think that the moisture would keep the glob of virus viable longer. Isn't it the cracking of the viral coat that inactivates it? Well, obviously drying out doesn't cause it problems...

I wonder if humidity has a Ph that affects it in some way?

[sharon sanders]

Re: Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification

Bump this.