RH stands for relative humidity. It indicates how much water vapor is present in the air compared to the maximum possible amount of water vapor for that air temperature. Therefore, it is expressed as a percentage, with values ranging from 0 to 100%.
Optimal RH Level?
Indoor relative humidity is generally considered optimal between 30% and 50%, and should ideally remain below 60%.
Within this range, indoor conditions are more comfortable and can help reduce the survival and transmission of certain viruses, bacteria, and allergens. As relative humidity moves outside this range, indoor air quality and comfort may be affected.
Air is typically considered too dry when RH drops below 20%, and too humid when it rises above 80%, both of which can negatively impact health and indoor environments.
How Does RH Affect You?
Low humidity can lead to discomfort such as dry skin, irritated eyes, sore throat, and increased susceptibility to colds and respiratory irritation.
High relative humidity can worsen respiratory symptoms, particularly for people with asthma or allergies. It also creates favourable conditions for mould growth and dust mites, which can further affect indoor air quality and health.
Both very low and very high humidity levels may influence the spread and survival of certain viruses, highlighting the importance of maintaining balanced indoor humidity.
How to Improve RH?
Monitoring indoor humidity levels can help you maintain a healthy balance. Using an indoor air quality sensor allows you to track RH in real time and act when needed.
If RH levels in your home are too low, consider using a humidifier to increase moisture in the air. Adding plants can have a small positive effect, although dedicated humidifiers are generally more effective.
If RH levels are too high, using a dehumidifier can help reduce excess moisture. Improving ventilation – for example by airing out rooms or using mechanical ventilation – is also an effective way to lower humidity levels.
High RH may indicate underlying issues such as water leaks or insufficient ventilation, so it is important to identify and address any potential sources of excess moisture.