Absolute humidity simply explained

Our air is enriched with water: more precisely, with water vapor. This water vapor is constantly present, but fluctuates depending on the temperature and then becomes more or less noticeable. If the air is warmer, it can also absorb or bind more water. We feel this, for example, in muggy summer weather or in tropical rain, which brings larger drops and more water with it. If, on the other hand, the air is cold, it absorbs less water. Then we feel a dry air on cold winter days. The phenomenon is particularly evident in people who wear glasses: if you come into a warm room from fresh temperatures, your visual aids fog up.

Absolute Humidity (φ): Causes & Origin

Absolute humidity (φ) describes the water vapor density, i.e. the total amount of water contained in a given volume of space. Absolute humidity is expressed in grams, whereas relative humidity is expressed as a percentage.

Relative humidity (p) depends very much on temperature: air at 30 °C temperature can absorb 31 grams of water per cubic meter (31 g / mᵌ), air at 5 °C temperature only 7 grams of water per cubic meter (7 g / mᵌ). The consequence at cold temperatures: condensation or dew forms because the air cannot absorb as many water molecules. So if you often have water droplets on the window in your bedroom in winter, you should air it accordingly more often and raise the temperature a little.

So how does more water vapor get into our rooms? Quite simply: through our breathing. Because we release moisture into the environment every time we breathe out. The more people there are in a room, the more the water vapor in the air increases. But plants also give off water, and even showering, drying laundry or cooking produces moisture that enriches the ambient air. The only thing that can help here is an exchange of air - ideally through shock ventilation.

Some building materials absorb more moisture than other objects due to their surface properties: for example, untreated wood, lime, plaster or brick. Materials such as paper or textiles also store moisture over a long period of time and release it again when the humidity is low, for example books, upholstered furniture, curtains or carpets.

Many new buildings are not yet fully dried out. The moisture contained in the building materials is then released into the ambient air, i.e. also into the interior of the room. To prevent health hazards or mold, you should increase ventilation in these cases - ideally over a complete heating period.

Health consequences of the measured value Absolute humidity

Low humidity weakens the immune system, dries out the mucous membranes and leads to skin irritation, burning eyes and reduced breathing capacity. This weakens the organism and also encourages viruses and bacteria to remain in the air longer - the risk of infection increases. If the air is more humid, on the other hand, the pathogens are enveloped by a film of water. Their mass then increases and so does their rate of descent. They are virtually lying on the ground. Another problem with low humidity is that dust is more easily stirred up. This is a particular burden on allergy sufferers. And if the air is very dry, there is an increase in electrostatic charges, which are discharged when we walk across the carpet or touch metallic materials.

Excessive humidity promotes discomfort, circulatory problems, impairs productivity and promotes mold. High temperatures and high humidity become uncomfortable because the body cannot cool itself by sweating. This is because evaporation is limited, since the ambient air can hardly absorb any water. A film of sweat remains on the body.

If mold spores get into the body, conjunctivitis, gastrointestinal complaints, joint pain, asthma or migraines occur more frequently. At a high relative humidity of 60%, house dust mites also multiply, releasing correspondingly more allergens and burdening allergy sufferers.

However, humidity is also perceived differently by different people. These assessments are subjective and can quickly be wrong. It is therefore advisable to check the absolute humidity objectively. An air measuring device such as the air-q, which constantly measures the air humidity and issues corresponding warnings if the limit values are exceeded, can help here.

What helps against too high humidity?

Place a bowl with salt. The crystals bind the moisture.
Take short showers if possible & avoid water vapor, e.g. when cooking (switch on fume hood).
Maintain recommended room temperature.
Measure absolute humidity with an air meter such as the air-Q and ventilate regularly.

What helps against too low humidity?

Use humidifiers: either appropriate devices or natural humidifiers such as plants that need a lot of water, watered accordingly and release the moisture through the soil and their leaves.
After showering or cooking, distribute the resulting moisture into the other rooms via open doors.
Avoid unnecessarily high air exchange rates, e.g. due to constantly tilted windows, leaky doors, windows or chimneys.
Measure absolute humidity with an air meter such as the air-Q and ventilate as needed.