During our cold winters, relative humidity levels tend to remain low meaning the air is drier. Ideally the inside humidity levels should be maintained between 35-50%. Humidity levels higher than 50% can cause moisture to accumulate on your windows. When indoor air is too dry asthma and allergy symptoms can worsen, cold and flu viruses may spread more rapidly, and you may be more prone to sinus infections. You may suffer from dry skin, chapped lips and dry air passageways. Dry air is also damaging to your home. Wood and other building materials as well as furniture are robbed of moisture when the air is dry. Cracks and damage can occur to flooring, trim, and even framing around windows and doors. Moist air also retains heat better helping your heating system function more efficiently and increase overall home comfort.