Optimum Relative Humidity
Consequences of High Humidity
Wet crawlspaces/basements contribute to the cupping of wood floors and the deterioration of floor joists, beams, sub-flooring, insulation, and electrical-mechanical systems. Excess moisture encourages mold growth on wood and on any other organic material.
Crawlspaces/basements are a major source of air infiltration that permeates up into the living area, transmitting odors, carrying moisture, and creating an environment conducive to molds, pests, and dust mite infestation.
Controlling a living space’s relative humidity (the amount of water vapor that exists in a gaseous mixture of air and water) can have a large impact on preventing molds, bacteria, dust mites, viruses, mildews and other irritants. Allergens like molds and fungi thrive in relative humidity conditions above 60%, leading to a variety of ailments including asthma, allergies and a variety of respiratory infections. Dust mites, the leading cause of allergies, thrive in as little as 50% relative humidity.
While humidity is important there is also the issue of airborne pollutants. Dust mites, mold spores, pet dander, weeds, grasses, pollens, and other allergens are floating in the air, perhaps you can see them floating about when the sun shines in through a window. A MERV-11 rated filter can remove particles from 1.0 to 3.0 microns in size from the environment and a HEPA filter is 99.97% efficient at capturing particulate from 0.3 microns or larger that pass through it. One of these filters mated with a blower fan of proper size can effectively remove a large majority of airborne indoor pollutants. Additionally there are also carbon and potassium permanganate blend filters available that remove odors, chemicals and gases.