Indoor humidity: Getting fresh air inside

January 1, 1

Our health and wellbeing depend on indoor humidity that’s “just right”.


We spend a lot of time inside, so it’s important that the environment within our homes is healthy. Too much or too little humidity can be harmful, but there are steps we can take to make sure it’s always at the optimum comfort level.

People are healthiest inside buildings when the relative humidity level is between 45 and 55 percent. Below this, there’s a risk of dry, itchy skin, irritation to the eyes and nose and disturbed sleep. Low-humidity conditions are also favourable for viruses, which increase the risk of illness like colds or pneumonia. High humidity, above 55 percent, increases the risk of mould, which can release spores that exacerbate asthma symptoms and respiratory diseases. Right now, an estimated 84 million Europeans live in damp dwellings that can threaten their health.

Given the potential problems, it’s worth paying attention to humidity. It changes throughout the year (lower in winter and higher in summer) and with the number of people or amount of activity in a room. You can control it simply by opening windows, for example, which helps reduce CO2 levels and keeps the air fresh. Dampness and interior condensation are signs of excess humidity, and if the walls or floors feel particularly cold, they can cause condensation to build up when warm, moist air comes into contact with them.

An air-tight building that’s well insulated all round is essential for indoor comfort. ROCKWOOL insulation helps to keep interiors at the optimum temperature and humidity because of its thermal properties and breathability. And as these qualities stay the same over time, a building’s occupants can have a healthy environment for the long term too.

Living in damp dwellings

Europeans living in damp dwellings

Optimum humidity indoors

is the optimum relative humidity indoors

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