Humidity by definition is the amount of water vapor in the air. Humidity can vary depending on climate, location, and season with an ideal humidity between 30-50%. Too much or too little humidity can cause issues not only to your home but to your health. At low humidity, your skin can become dry and your nasal cavities and eyes can become irritated and itchy. A high humidity can cause your home to become stuffy with condensation building on the walls. This is the perfect environment to invite thriving bacteria, dust mites and molds which can cause flare ups in allergies and asthma.