Makes A Building Far more Comfortable in Winter Phytofilters have the ability to increase relative humidity within a structure. Relative humidity: The percentage of moisture in the air compared to the actual amount of moisture that air can hold. Looking on the next chart you can see how low the relative humidity of air in a building becomes, especially in winter once outside air is brought inside through mass ventilation & then heated. 1

If outside air is fully saturated, in other words it has 100% relative humidity, at 0 degrees F. & then is taken in through the ventilation duct and heated to 70 degrees F., the relative humidity of that same air decreases to 6% (1.5/25) If outside air has 100% relative humidity at 30 degrees F. & is drawn into a building and heated to 70 degrees, its relative humidity drops down to 22.4% (5.6/25). Thus indoor air in a building is often lower in winter than what a person would experience if he were in the Sahara Desert where average relative humidity is 25%. Such a situation does not make for human comfort. 2 Temperature Saturation Vapor Pressure Saturation Vapor Pressure (mbar, millibar, mb) ( o C)( o F)

Most buildings in winter have very dry air: – because they lack humidifiers, Which are high maintenance and give rise to mold; & – because they take in winter air from outdoors and simply heat it. But if a building installs a plant air purifier, relative humidity can be increased in winter because indoor air is continually able to pass through the phytofilter’s moist filter bed, where it picks up needed moisture without any added danger of mold. 3

With indoor air having a necessary level of moisture or relative humidity which Phytofilters provide inhabitants are protected from having: – Sore Throats – Dry & Itchy Skin & – Dried Out Mucus Membranes, Which Lead to Increased Susceptibility to Colds and Flu, & an Increase in Airborne Viruses and Germs – Further, cold and flu germs and viruses actually increase When Relative Humidity is Not between 47-60% which a phytofilter system can provide. 4