Know Your Indoor Environment With an AcuRite Pro Accuracy Indoor Temperature and Humidity Monitor with Alarms, you get reliable Information that can help you ensure a comfortable living space and better air quality, all while taking steps to preserve your home's interior and valuable possessions. Compact, easy to use and offering a variety of mounting options, it's a must-have for any home or office. Humidity Level Indicator The humidity level indicator easily conveys whether humidity levels are too low (blue), ok (green) or too high (red) at the top of the display, based on relative humidity (RH) guidelines set by the Environmental Protection Agency (EPA) for health and comfort. LOW: Less than 25% RH indicates a dry environment: Between 25%-55% RH indicates a comfortable environmentHIGH: Over 55% RH indicates a humid environment Why Are Humidity Levels Important. Too much humidity can cause an increase in biological pollutants, like mold, bacteria, viruses, fungi and dust mites that can trigger respiratory health ailments. Not enough humidity in your home can lead to nosebleeds, painful skin irritation, difficulty breathing and damaging static electricity. Humidity levels also have an impact on the plant growth, as well as the health and comfort of animals. 1-year limited warranty.