According to the Environmental Protection Agency, common health issues associated with poor indoor air quality include eye irritation, sore throat, congestion, sneezing and wheezing, skin rash and headaches. These problems can be directly related to the presence of fungi and dust mites which thrive on excess moisture – typically relative humidity levels of at least 60%. A 1999 study performed by Mayo Clinic researchers indicated the cause of most chronic sinus infections is an immune system response to fungus. In addition to health issues, excess moisture can damage your home and contents. Indoor RH above 50% can cause damage to wood floors (cupping), paint, sills, artwork, furniture and electronics. Pests thrive in moist areas, thus termites are more likely to be present if RH is not properly maintained.