Improve indoor air for healthy living

Headaches, burning eyes, irritated respiratory tract - all of these symptoms can be linked to the quality of indoor air. Several factors are responsible for its quality, such as humidity, temperature, regular ventilation, etc. But what can you do to ensure good and healthy indoor air? What can you pay attention to before, during and even after building? We provide you with the answers to these questions and more.

The importance of good indoor air

A familiar feeling for most of us: you're sitting in a meeting, and everything is proceeding as normal. After a while, you start to feel a bit tired and your concentration wanes. Eventually, you get up to briefly leave the room and come back a few minutes later. As you enter the room, you are met with a heavy smell that makes you notice how stale, heavy and odourful the air inside has become.

We humans do not have a built-in sensor with which we can measure the quality of the air. We only feel the effects it has on us. Only through this, or as described in the example above, when we have a direct comparison, do we consciously perceive the quality of a room’s air.

If the indoor air is only of unhealthy quality for a certain period of time, the body can neutralise this relatively quickly. However, if you are in such rooms for a longer time, this can not only affect the body, but also the psyche in the form of sluggishness, dejection or a lack of concentration.

What is a "good indoor climate" anyway?

Schadstoffe in der Raumluft Schadstoffe in der Raumluft

Simply put, a good indoor climate means good air. But what is "good air"? What should we pay attention to and are there certain standard values that we should follow, especially during building processes?

Good air is characterised by a low content of dust particles, pollen, bacteria, fungi, mould spores, viruses, gases and other potentially harmful substances. Such substances include volatile organic compounds, nitrogen dioxide and carbon monoxide. In addition, there should be no unpleasant odours, especially those that cause headaches, nausea, coughing and eye irritation.

Air quality is therefore defined by several parameters, including:

  • Temperature
  • Humidity

An optimal indoor climate is generally said to exist at a relative humidity of 50 percent and a room temperature of 20 degrees Celsius. This can vary somewhat depending on the room. In a bedroom, for example, it can be a little cooler – whereas in a living room or bathroom, a few degrees higher is ideal.

The consequences of poor indoor air 

A good indoor climate and good indoor air are of great importance for physical well-being. A wide variety of symptoms can occur if indoor air deteriorates in quality – ranging from poor concentration and headaches to nausea and irritation of the eyes, respiratory tract and mucous membranes.

The importance of good indoor air therefore should not be underestimated. Particularly in public buildings, schools and kindergartens, but also hospitals, where children or risk groups are present: care must be taken to ensure a good indoor climate with the lowest possible concentration of pollutants.

"Sick Building Syndrome"

“Sick building syndrome", or SBS for short, describes mostly non-specific complaints that occur in people who have spent a long time in one building. Most of the time, this is an office space.

Symptoms include irritated eyes and mucous membranes, headaches or allergies. The cause is not entirely clear, but it is suspected that there is a connection with an increased concentration of pollutants. According to measurements by the Federal Ministry of Building, this is six to eight times higher indoors than outdoors.

A short introduction: air pollution then and now

In the 19th and 20th centuries, these Air pollutants were mainly microbial contaminants and combustion products from lighting and heating. However, pollutants now mostly originate from organic compounds in building materials and furnishings, but they can also be of natural origin.

Due to low air exchange, they can accumulate indoors. Improved thermal insulation and the installation of joint-tight windows, as they have been installed since the oil crisis in the 1970s, can contribute to this accumulation. According to the WHO, we are thus exposed to more environmental pollutants indoors, than we are through ingestion of food, water or outdoor air.

Which pollutants can be present in indoor air?

Pollutants can enter indoor spaces in different ways. On the one hand, they can come from outside road traffic, but can also come from inside elements. Common sources are cigarette smoke and gas cookers, but also various building materials or processing, from which pollutants either dissolve immediately or do so over time – and therefore get into the air. We have briefly summarised different forms of pollutants here:

Easy to remove
Leicht zu entfernende Schadstoffe in der Raumluft Leicht zu entfernende Schadstoffe in der Raumluft
  • Dust: Everyone knows it, everyone has it, everyone tries to minimise it: house dust. In a normal flat, around 6 milligrams of dust per square metre form every day. Sources of dust here are mainly upholstery, carpets, dryers as well as our own bodies. Every day we lose almost 2 grams of dead skin cells. However, dust particles can also enter any interior through traffic or agriculture fumes. It is important nonetheless to ventilate regularly because there is less dust outside than there is indoors. Regular vacuuming can also help.

  • Pollen and mites: House-dust mites in mattresses can trigger some allergies. In the meantime, however, there are allergy-friendly versions that can provide relief. Regular vacuuming and cleaning keep the mite count low. Especially if you struggle with hay fever in the spring or summer months, air cleaners, special filters on hoovers and airing out your space at times when there is less pollen (in the morning or evening) can also help.

  • Tobacco smoke: Around 40 substances in tobacco smoke are harmful to health and are even considered carcinogenic. It is not only the smoke that is directly inhaled that is dangerous, but also the smoke that gets into the air. So, think carefully about whether you want to smoke in your home or whether you would prefer to take it outside.

  • Odours: They are not only unpleasant, but they can also lead to health problems. So, the first step is to find out where the smell is coming from. Odours can be easily eliminated if they are coming from food leftovers or fresh paint for example, but they can also be the first signs of leaks in a room, or mould, or rotting building materials caused by moisture.

  • Carbon monoxide (CO): CO is a colourless and odourless gas that is released during incomplete combustion processes. It can enter indoor spaces mainly through leaky cookers, gas ovens or fireplaces. Elevated concentrations can also occur in car workshops or garages due to car exhaust fumes. In high doses, carbon monoxide is life-threatening. Especially if you have a fireplace, a stove or a gas boiler, you should use a carbon monoxide detector for your own safety. Then you will know immediately if there is any kind of problem and can keep a good overview.


Difficult to remove
Schadstoffe in der Luft Schadstoffe in der Luft
  • Nitrogen dioxide (NO2): NO2 is a colourless gas that occurs naturally in the atmosphere. It is mainly produced by combustion processes. However, because of industrial emissions, NO2 can occur in large quantities indoors. Nitrogen dioxide is an irritant gas and can be particularly harmful to the lower respiratory tract.
  • Radon: You might not think of this noble gas when you start building. It occurs naturally in rocks such as granite or limestone. Not only can it enter indoor spaces from the ground, but certain concentrations of the carcinogenic noble gas can also be found in mineral building materials.
  • Volatile Organic Compounds (VOCs): VOCs are chemicals that evaporate easily from surfaces and dissolve in liquids. They are present in many products and materials. Some examples are solvents, paints, adhesives, cleaning agents, pesticides, fuels, plastics and rubber. Loose items can be easily removed from the room. Fixed building materials are more difficult to remove and require renovation and remediation. One of the most common indoor VOCs is formaldehyde.


Formaldehyde, also called methanal, is a colourless and water-soluble gas with a pungent odour. In nature, this gas can be formed by incomplete combustion of carbon-containing objects. In liquid form, it is used as formalin as a disinfectant in hospitals.

Indoors, there are countless sources from which formaldehyde can escape and enter the indoor air. It is a basic substance for chemical compounds that are necessary to produce chipboards, adhesives, varnishes, paints ... Formaldehyde is considered harmful to health and even carcinogenic, as it can lead to headaches and malaise whilst also irritating the mucous membranes and respiratory tract.


How do I ensure good indoor air?

Safe and secure - that's how you want to feel in your home. To make sure that this is really the case, you should pay attention to more than just appearance before you start building. The basic rule here is to build to a high standard instead of cost-intensive renovation, as numerous pollutants can seep into the air from walls, floors and furniture.

Even if a house is already standing, you can often improve the indoor air with just a few household remedies before it becomes a health hazard.

We have briefly summarised a few steps that you can consider taking in connection to building a house.

Step 1: Thinking about indoor air before building a house

Building a house is probably one of the most important and biggest decisions in life. Therefore, in addition to the financial aspects, you should also take a closer look at the property you are considering and ask yourself the following questions:

  • Where exactly is the plot located and what is in the immediate vicinity?
    Based on this question, one can already determine possible air polluters or air pollution before the start of construction. In addition to industries or road traffic, agriculture can also cause a certain amount of air pollution, which can later find its way into interior spaces.
  • What is the subsoil like?
    To avoid unpleasant surprises later on, you should take a closer look at the subsoil. The noble gas radon can be found in rocks such as granite or limestone, and can later rise up into the house from below. If the property is located in a marshy area, it is particularly important to have a good foundation or basement. Therefore, we recommend clarifying the groundwater level in advance with the builder. You should also check here for any problems with moisture after moving in, so that any damage can be repaired straight away before too much moisture can penetrate the brickwork.
  • What was there before?
    Properties and houses should be checked for possible residues such as oils or asbestos.
  • Are there any building restrictions or bans?
    You should also find out in advance about possible restrictions. It is best to consult upon this with the help of experts. For example, there are so-called drinking water protection zones I and II. Here, for example, the use of geothermal energy is prohibited according to the ordinance on protective regulations.
Gute Raumluft mitbedenken Gute Raumluft mitbedenken

Step 2: Decide in favour of good indoor air during construction

If everything is in order with the property, building can begin. The rule here is that if you build healthily, you can live healthily. The right building materials are therefore essential because they prevent pollutants from entering the indoor air in the first place. Natural materials are often good alternatives, but here, too, a closer look is often necessary as natural building materials may have been treated with chemicals such as wood preservatives or insecticides. Eco-certifications such as Blue Angel, EU Eco-Label, natureplus or Emicode can help in the selection of materials, but so far there is no uniform regulation. TÜV certificates can also be helpful.


What materials are available for healthy building?

  • Wood: Wood has a positive effect on an indoor climate in several respects: it is anti-allergic, anti-electrostatic and anti-bacterial. Wooden furniture therefore does not attract dust or irritate mucous membranes. Wood fibre insulation boards with climate chambers, for example, are a healthy and ecological alternative to plasterboard. Wooden furniture is also a long-term CO₂ store and is climate neutral. The only thing to watch out for here is gluing, varnishing or sealing.
  • Loam and clay: Loam has been used as a universal building material for thousands of years. Whether in the form of fired clay bricks, clay building boards or as a plastering material – the eco-balance speaks in favour of clay. This natural material offers many advantages: easy processing, good heat storage, almost no waste, regulates air humidity and thus contributes positively to the indoor climate.
  • Natural stone: Natural stone can be used both indoors and outdoors. It creates a special atmosphere and is suitable as flooring, wall cladding or worktop. Natural stone stores heat, is extremely durable and stable.
  • Lime: Lime has also been used for thousands of years. It is harder than clay and can be made hydrophobic without the use of chemicals. This makes it possible to create high-gloss, water-repellent and jointless surfaces. Lime is also a good choice for the indoor climate. Due to its alkaline pH value, there is no danger of mould, and it also contributes positively to the regulation of humidity in the room.
  • Bricks: Since bricks are fired at very high temperatures and they are pure and inorganic materials, there is no danger of biological organisms binding to them and growing. Brick buildings also do not release gases or allergens - ideal for a good indoor climate.
  • Straw, hemp and plant fibres: The possible uses of straw, hemp and other plant fibres are enormous. Straw, for example, has been used as a lightweight aggregate for centuries. These materials are ideal insulating materials, are suitable for sealing windows and doors and are suitable building materials for ensuring a good indoor climate. The materials offer many advantages: they are breathable, recyclable, free of harmful substances and help regulate air humidity. Compared to sheep's wool, however, you need more material, which makes it more expensive to use. Hemp also has no air-improving properties. In the event of water damage, sheep's wool can absorb about 30 per cent without loss of thermal insulation and then dry out again. In such cases, hemp must be replaced, and there is also a risk of mould growth.
  • Sheep's wool: fire protection, indoor air, acoustics, air quality, recycling, thermal insulation - sheep's wool stands out in all areas. Especially regarding an indoor climate, sheep's wool is the ideal choice: due to its basic protein component keratin, the material can absorb and neutralise toxins such as formaldehyde. In addition, moulds do not stand a chance here. Due to its hygroscopic property, sheep's wool can absorb up to 33 percent of its own weight in moisture - but the thermal insulation remains intact.
Während des Bauens Raumluft bedenken Während des Bauens Raumluft bedenken
Wundermittel Schafwolle Wundermittel Schafwolle

Schritt 3: 7 Maßnahmen, um auch nach dem Hausbau die Raumluft zu verbessern

Steht euer Haus bereits und ist die Schadstoffkonzentration nicht allzu hoch, kann man mit relativ einfachen und auch kostengünstigen Tricks die Raumluft verbessern. Wir verraten euch unsere 7 besten Tipps:

1. Frische Brise: Richtiges Lüften ist oft die einfachste, aber auch effektivste Lösung, um die Raumluft zu verbessern. Dabei gilt allerdings: Stoßlüften ist besser als Dauerlüften. Durch gekippte Fenster findet kein Luftaustausch im Innenraum statt. Er kühlt lediglich aus. Außerdem steigt so die Schimmelgefahr. Ideal wäre drei- bis viermal am Tag fünf bis zehn Minuten Stoßlüften, so gelangt frische Luft in den Raum und die schlechte Luft wird ausgetauscht.

2. Keine Chance für Staub: Regelmäßiges Staubwischen und Staubsaugen hat nicht nur den Effekt, dass alles makellos erstrahlt, es sorgt auch dafür, dass weniger Staub in die Raumluft gelangt. Viele Allergiker schwören bei Staubsaugern auch auf sogenannte HEPA-Filter. Diese filtern sogar Kleinstpartikel wie Feinstaub, Allergene oder Pollen und Sporen aus der Raumluft.

3. Auf das Mittel kommt es an: Lösungsmittelfreie Reinigungsmittel beinhalten in der Regel keine aggressiven Inhaltsstoffe, die in die Raumluft gelangen können. Es gibt mittlerweile viele biologische Reinigungsmittel im Handel. Auch Hausmittel (Link Beitrag Hausmitteltest) sind nicht zu unterschätzen.

4. Weniger ist mehr: Umso mehr Möbel, Polster, Vorhänge und Dekogegenstände, desto mehr "Staubfänger" und "Staubproduzenten" stehen im Raum. Wenn man sich also von manchen Dingen trennen kann, dann kann das auch zu einer besseren Raumluft beitragen.

5. Es grünt so grün: Zimmerpflanzen sind wunderschön anzusehen, bringen Leben und Farbe in den Raum und reinigen auch noch die Luft. Sie filtern die Schadstoffe aus der Raumluft und geben saubere Luft wieder ab. Manche können sogar chemische Schadstoffe abbauen. Eine Pflanze pro neun Quadratmeter ist hier der ideale Maßstab. Wie wäre es daher mit einem Gemeinen Efeu, einem Drachenbaum oder einer Friedenslilie? Diese drei gelten als perfekte Luftreiniger.

6. Heiß oder kalt? Auch die Zimmertemperatur spielt bei der Luftqualität eine Rolle. 19 bis 22 Grad Celsius sind ideal. So können sich Sporen oder andere Bakterien nur schwerer ausbreiten.

7. Zu trocken oder zu feucht? Um Schimmel zu vermeiden, muss man auf die Luftfeuchtigkeit in Innenräumen achten. In Innenräumen liegt die perfekte Luftfeuchtigkeit zwischen 40 und 60 Prozent. Denn Schimmel sieht nicht nur nicht schön aus, er ist auch gesundheitsschädlich.

Richtiges Lüften Richtiges Lüften
Regelmäßig Staubwischen Regelmäßig Staubwischen
Lösungsmittelfreie Reinigungsmittel Lösungsmittelfreie Reinigungsmittel
Grünpflanzen Grünpflanzen

Step 3: 7 measures to improve indoor air even after building a house

If your house is already standing and the pollutant concentration is not too high, you can improve the indoor air with relatively simple and inexpensive tricks. Here are our 7 best tips:

1. A fresh breeze: Proper ventilation is often the simplest yet the most effective solution to improve indoor air. However, it is better to ventilate at regular intervals than continuously. When windows are tilted, there is no exchange of air in the interior, this function merely cools down a room. This also increases the risk of mould. The ideal would be to ventilate three to four times a day for five to ten minutes, so that fresh air gets into the room and the used air is exchanged.

2. No chance for dust: Regular dusting and vacuuming not only has the effect of making everything shine immaculately, but it also ensures that less dust gets into the room air. Many allergy sufferers also swear by so-called HEPA filters in hoovers. These filter even the smallest particles such as fine dust, allergens or pollen and spores from the room air.

Richtiges Lüften Richtiges Lüften
Regelmäßig Staubwischen Regelmäßig Staubwischen

3. It's all about the product: Solvent-free cleaning agents usually do not contain any aggressive ingredients that can get into the indoor air. There are now many biological cleaning agents on the market. Home remedies (link to article on home remedy test) should not be underestimated either.

4. Less is more: The more furniture, upholstery, curtains and decorative objects, the more "dust catchers" and "dust producers" there are in the room. So, if you can part with some of these things, a minimalist lifestyle can also contribute to better indoor air.

5. Greenery: Houseplants are beautiful to look at, bring life and colour into the room and also clean the air. They filter pollutants from the indoor air and release clean air. Some can even break down chemical pollutants. One plant per nine square metres is the ideal measure here. So how about a common ivy, a dragon tree or a peace lily? These three are considered perfect air purifiers.

6. Hot or cold? Room temperature also plays a role in air quality. 19 to 22 degrees Celsius are ideal. This makes it harder for spores or other bacteria to spread.

7. Too dry or too humid? To avoid mould, you must pay attention to the humidity indoors. The perfect humidity level indoors is between 40 and 60 percent. Mould is not only visually displeasing but is also harmful to one’s health.

Lösungsmittelfreie Reinigungsmittel Lösungsmittelfreie Reinigungsmittel
Grünpflanzen Grünpflanzen

Our conclusion regarding the improvement of indoor air

The role of that indoor climate plays in relation to our health is often underestimated. We then tend to have a rude awakening once the symptoms begin to occur: coughs, headaches, eye irritations, etc. can be the consequences of negligent building processes. Even before and during construction, you can pay attention to a few things to ensure healthy indoor air right from the start. But there are also some tips and tricks for improving the indoor climate afterwards.