What is formaldehyde?
Formaldehyde (pronounced: form-aldehyde) is a organic compound and is one of the most important organic raw materials in the chemical industry. It is used in a wide variety of areas, such as building materials and dyes, pharmaceuticals and textile finishes. It is therefore not surprising that it is also found indoors. Wood-based materials such as chipboard, floor coverings or even furniture can contribute to an increased and harmful concentration.
With Room temperature is Formaldehyde gaseous and Free formaldehyde dissolves from the objects. The "living poison" is also known under the names Formic acid aldehyde, methanal or Oxomethane is known. It is the simplest of the aldehydes, as it consists of only one aldehyde group (CHO) and one hydrogen atom (H). The structural formula of formaldehyde is therefore: CH2O.
A closer look at the chemical properties of formaldehyde
- The Aggregate state is gaseous
- Due to its molecular structure, formaldehyde is Very easily soluble in water
- In dissolved form it is used as Formalin labelled
- The melting point of formaldehyde is -117 degrees Celsius
- The boiling point is -19 degrees Celsius
How can I measure the concentration of formaldehyde
In the meantime, various Measuring device on the market that can determine formaldehyde in indoor air in real time. The measurement is usually carried out via a electrochemical sensor, to which the molecules dock.
The exact formaldehyde concentration can also be determined using a Laboratory can be determined. For this purpose, the room air is usually drawn onto a test tube for 30 minutes. Air pressure, humidity and temperature must be documented. The air in the test tube is then precisely analysed in the laboratory.
Formaldehyde is harmful to humans and animals Toxic and from a concentration of 30 ml/m³ there is even a danger to life. Since 2014, formaldehyde has been classified throughout the EU as a carcinogenic categorised. In Interiors applies a Guideline value of 0.1 mg/m³.
However, some people experience irritation of the mucous membranes of the eyes and respiratory tract or headaches even at concentrations below this guideline value. Most irritations are only temporary, but allergies can also develop. Formaldehyde-containing disinfectants must be labelled in accordance with the CLP Regulation. labelled such as "May cause allergic skin reactions".
If certification according to the DGNB (German Sustainable Building Council) is required, the target value of 0.05 mg/m³, i.e. half of the guideline value, must be adhered to. If the guideline value is exceeded, DGNB certification is not possible.
Where is formaldehyde used?
Formaldehyde is used in countless products and materials. As a result, it also easily finds its way indoors. Textiles, flooring, furniture, disinfectants and even cosmetics are all sources that can increase the concentration of formaldehyde indoors.
So let's take a closer look at a typical living room:
Wall colour
In paints and wall colours
Formaldehyde as
used as a preservative. The
Exposure to the pollutant
is at best only
temporarily, but then
usually at an alarming level.
Furniture
Chipboard is pressed,
glued wooden panels, for furniture
often with decorative
laminates are glued together. The glue
may contain formaldehyde, which
Furniture provides these via a
for a long time.
Decorative fabrics
Formaldehyde is used in
decorative textiles such as
carpets or curtains often
to make the fibre more stable
for carpets also
often used to connect the fibre
with the carrier fabric.
Disinfectant
Formaldehyde kills most
germs and is therefore
often in disinfectants.
Clothing
One speaks of "equipping",
when textiles contain certain
Properties through the use of
chemicals can be changed.
Formaldehyde is used to
e.g. often made crease-free.
Floor covering
With carpeting for
Fibre stabilisation, for laminate
or finished parquet for
Gluing the boards: Often
is also hidden in the
Formaldehyde flooring. Not
so with solid wood, rarely with tiles.
Floor adhesive
Resins are the basis of
adhesives: Vaporises the
solvent, a
Adhesive film. With the often
used formaldehyde resin
the pollutant then vaporises
slowly.
Soil sealing
Raw wood parquet or wooden floorboards
are often used for protection
sealed. Take care with the
Choice of sealing: It can be
contain formaldehyde. There are
but also some that
Absorb formaldehyde.
What to look out for to avoid formaldehyde
Anyone who believes that there is no way around formaldehyde is mistaken. There are now various Seal of quality and Labellingthat make it easier to maintain an overview.
These seals include, among others "Blue Angel". This is an eco-label of the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety.
- The criteria are Emissions, ingredients and a Environmentally friendly disposal.
- If all categories are rated positively, the seal is awarded. Products or product groups that are currently labelled with this seal include furniture, electrical appliances, cleaning products, paper, vehicles and various building materials (paints, varnishes, insulating materials, etc.).
- The audit is carried out by External experts.
- Already since 1978 there is this seal.
In addition to the "Blue Angel", there are other environmental labels. The ISO standard makes a rough distinction between three types of environmental labels.
- To Type-I is the "Blue Angel".
- To Type-II These include environmental supplier declarations. In most cases, an independent review does not take place. The requirements of the DIN EN ISO 14021 must be complied with, however. For example, certain requirements must be met for protected terms such as "compostable", "recyclable" or "reduced energy consumption". The term "sustainable" is also prohibited in this context, as there are no procedures for measurement or assessment criteria at product level.
- Eco-label of the Type-III are subject to the requirements of the DIN EN ISO 14025. They display additional information on environmental and health protection. They are issued by external organisations. In contrast to the two previous types, the target group is not building owners, but primarily economic players such as planners or auditors.
The importance of good indoor air
If the limit value for formaldehyde is exceeded, the question arises: Can formaldehyde be neutralised? The answer is yes.
In industry, especially in the construction sector, workers come into contact with various paints or solvents. Certain extraction systems are used here to reduce the concentration of formaldehyde. However, installing such a system in your own living and working area would prove to be rather difficult.
Nevertheless, there are many tips and tricks to improve indoor air quality. And so there are also some very effective ways to get formaldehyde out of the living space in particular:
- Regular shock ventilation works wonders. The air is completely exchanged and the formaldehyde concentration can be kept low.
- Green plants are real "pollutant killers". They not only neutralise indoor toxins, but also ensure an ideal living and working environment through their oxygen production. These miracle weapons of nature include the following houseplants:
- Areca palmThe popular palm tree is a real stimulant. As well as neutralising formaldehyde, it is also effective against xylene and toluene, substances that can cause tiredness and discomfort.
- Birch figFormaldehyde and ammonia don't stand a chance with this green plant.
- Rubber treeThis houseplant takes up the fight against formaldehyde like no other. It has an above-average degradation rate.
- Real aloe / aloe veraAloe vera is known as a medicinal plant and is an ideal source of oxygen. As a houseplant, it also breaks down small traces of formaldehyde in the air.
- IvyIt is not only a talented climber that thrives in partial shade, ivy is also a good degrader of formaldehyde.
- PoinsettiaThis green plant not only spreads Christmas cheer, but also breaks down slight traces of formaldehyde in the air.
- If you only have limited green fingers, you can now rely on various Ventilation systems or Air purifier can be used. However, if the concentration of formaldehyde is too high, you must ensure that HEPA filters do not catch the formaldehyde molecules due to their small size. A combination of photocatalysts with activated carbon filters is best suited. In addition to neutralising formaldehyde, such air purifiers can also remove allergens, bacteria, pollen and mould spores.
Building products: Is research being carried out here?
Bio-based wall paint
70 % less formaldehyde in the air just by using a certain wall colour? That sounds almost too good to be true. The Innovative indoor air technology from Sigma Fresh Air, this is no longer a dream. A double coat of paint does the trick, neutralise up to 70 % of the formaldehyde concentration and for years to come. Biofa offers another option. Here, a special Biological primer under the actual wall colour. Formaldehyde is broken down here by the keratin bond in a similar way to sheep's wool. An additional advantage of the primer is that it strengthens the substrate. However, due to the small quantities of formaldehyde-absorbing substances, the "filter performance" decreases rapidly compared to other methods. On the other hand, the colour can be reapplied relatively easily and the "filter performance" is restored.
Rigips boards with air purification effect
There are also improvements and product developments in the interior fittings. Air-purifying panels for walls and ceilings are already on the market. Rigips offers boards with the premium air purification effect "Activ Air". Formaldehyde and other volatile organic pollutants are absorbed by the boards and neutralised by a special active complex rendered harmless. According to calculations, this effect At least 50 years hold.
Minerals in chipboard and plywood
Around 85 % of all wood-based materials can be expected to contain a formaldehyde-based adhesive. In 2010, researchers from the Fraunhofer Institutes for Wood Research WKI in Braunschweig and for Silicate Research ISC in Würzburg discovered that synthetic zelolite Y absorbs pollutants. Tests with sample chipboards made of spruce wood showed a Reduction of formaldehyde emissions from the panels by around 40 %.
Formaldehyde-free white glue
Probably the best-known wood glue is the so-called White glue. This is a formaldehyde-free and solvent-free dispersion glue in liquid, milky-white formwhich becomes transparent when hardened. It is often used by both amateurs and professionals to join wood or wood-based materials. White glue is particularly suitable for decorative building boards. For static timber construction elements, the Formaldehyde-free alternative: PU glue (PMDI).
How sheep's wool neutralises formaldehyde
The protein fibre is one of the Natural fibres. He is Breathable, permeable to air and due to its good elasticity very dimensionally stable. Looking at their chemical composition, anhydrous sheep's wool consists of 97 % from proteinsthe Keratins can be allocated to the other segments. The remaining 3 % are formed structural lipids, mineral salts, nucleic acids and Carbohydrates. The elemental composition is characteristic of proteins, but what stands out is the high sulphur content of 3.5 %. This high content can be attributed to the Amino acid cystine can be traced back. Due to its high nitrogen content and moisture content, sheep's wool is only flame retardantr and burns only from a temperature of 560 degrees Celsius.
Sheep's wool is a Composite structurewhose fibres consist of two different cell types. The Epidermisthe so-called Cuticaconsists of fine scales that are arranged around the fibre like roof tiles. This scaly covering has an astonishing degree of cross-linking, which makes it very resistant to chemical substances and gives it mechanical toughness. Around this scaly cover is the Epicuticle. Inside the fibre are the Cortex cellswhich, at 90 %, forms the main component of the fibres. These are responsible for the mechanical properties of wool.
Sheep's wool and formaldehyde
The reactivity of wool with formaldehyde has been investigated in several studies since the 20th century. Initially, formaldehyde was used to improve the properties of wool. For example, it was used until the 70s as a wool preservative for dyeing used. Sheep's wool is now being used more and more in construction. Thanks to its proteins, it can chemically bind pollutants from the air, so it acts as a kind of Physical and chemical filter.
This binding capacity is particularly pronounced with formaldehyde. Laboratory tests showed that sheep's wool is approx. 96 % of formaldehyde from indoor air recorded. A release could not be proven. Accordingly, sheep's wool binds formaldehyde irreversible.
Installation of sheep's wool for air purification
Sheep's wool can be installed in different ways for indoor air decontamination. The most effective is Full-surface panelling the affected walls or ceilings with densely needled fleece. The wool can also be applied to a "suspended ceiling". A small additional benefit of this variant: The sound insulation is improved. Sheep's wool can also bind formaldehydes on the inside. This is the case, for example, with walls that are covered with ISOLENA sheep's wool products are insulated and clad with OSB boards. The type of wool, whether felted, needled or loose, is irrelevant and has no effect on its ability to filter pollutants.
The DWI recommends in its report "Chemical absorption of protein-reactive air pollutants by wool" (German) two installation variants of sheep's wool for effective pollutant remediation:
Pollutant remediation - Installation variant 1:
- Contaminated wall surface
- Sheep's wool fleece
- Interior panelling (plasterboard, wood panelling)
Pollutant remediation - installation variant 2:
- Contaminated wall surface
- Substructure
- Air layer
- Sheep's wool fleeces
- Ceiling panelling
The European Society for Healthy Building and Indoor Environmental Analysis (EGGBI) published in the report Report "Pollutant remediation with sheep's wool" Further information on the following contents:
- Possible uses of sheep's wool for indoor air decontamination
- Requirements for the fleece in formaldehyde remediation
- Processing sheep's wool for renovations
Research and practical implementation
The DWI (German Wool Institute) has carried out studies on the topic of "Absorption and binding of indoor pollutants by wool using the example of formaldehyde". Rooms contaminated with formaldehyde were simulated in test chambers in order to simulate the conditions that would occur if sheep's wool were used in remediation measures.
All the results painted the same picture: after two hours were able to 80 % of the formaldehyde load absorbed by the wool become. After 24 hours the value was 96 %. The asymptotic curve of the tests always pointed towards zero.
Also several Practical trials in residential and municipal buildingswhere it was usually not possible to remove the formaldehyde sources for structural reasons, showed a reduction in the formaldehyde concentration from approx. 0.06 to 0.2 ppm to below 0.05 ppm, which is less than half the BgVV guideline value.
- Test in controlled test chamber
- 96.7 % Formaldehyde degradation within 24 hours
- 80-88 % Dismantling within 2 hours
- Measurement during real refurbishment in buildings
- Follow-up measurement after 2.5 years + Scientific explanation of the permanent bond
→ DWI report "Absorption and binding of indoor pollutants" (PDF, German)
→ DWI report "Chemical absorption of protein-reactive air pollutants" (PDF, German)
→ Study "Sheep's wool as a reactive sorbent for indoor air pollutants (PDF, German)
→ Study "Sorption of indoor formaldehyde by wool" (PDF, English)
The dissertation offers a comprehensive, scientific treatise "Sorption of indoor air pollutants by wool" by graduate chemist Stefan Thomé. He systematically investigated how sheep's wool absorbs, binds and retains various air pollutants - in particular formaldehyde - in order to scientifically evaluate its use for indoor air decontamination:
Sheep's wool can Large quantities of formaldehyde from the gas phase, especially at 56 % relative humidity and 22 °C.
The recording takes place both via Chemisorption as well as Physisorption.
Wool shows a good Retention capacity of formaldehyde.
With longer storage (e.g. 8 months), the chemically bound formaldehyde is significantly reduced - to approx. one quarter of the original values.
Also Other aldehydes (e.g. glutaraldehyde, furfural) and non-protein-reactive substances such as toluene are effectively absorbed.
Examples of successful formaldehyde remediation
Upper Secondary School Centre East in Felben-Wellhausen, CH
Pupils and teachers complained about health problems shortly after moving into the new building. Measurements showed that the concentration of formaldehyde in the interior rooms was far too high. The refurbishment was carried out with the help of sheep's wool and proved effective:
- 46,6 % Formaldehyde reduced by sheep's wool
- Dismantling of the load-bearing ceiling construction prevents
- Healthy indoor air in the school building
→ Case study on formaldehyde remediation in a school building
Kindergarten refurbishment project in Langenfeld near Cologne
Elevated formaldehyde concentrations were found in kindergartens - a particularly critical finding, as children have a higher respiratory rate (→ see report Josef Spitzendorfer, sustainability-in-construction.com, (in German)) are particularly sensitive to pollutants.
The cause was chipboard on the walls and ceilings. Several attempts at renovation failed and a Demolition was considered. A room was sanitised with sheep's wool on a trial basis. Just a few days later, the level of formaldehyde was well below the legal guideline value of 0.1 ppm at 0.04 ppm. In the meantime, the entire kindergarten has been sanitised.
(Source: Research report "Sheep's wool as a reactive sorbent for indoor air pollutants" (PDF, German))
Realschule Eschenried, Sindelfingen DE
The lost formwork in the concrete ribbed ceiling and acoustic panels made of pressboard were the cause of increased formaldehyde values between 111 and 142 µg/m³. The trial remediation with sheep's wool showed a Improvement of the measured values by up to 47 %. Sheep's wool thus proved to be an effective measure for improving the air and was also used in the remaining classrooms for refurbishment.
→ Report by the expert office of Dr Roland Blessnig with detailed measured values (PDF, German)
Conclusion
As in normal life, it's the inner values that count when building a house. If you pay attention to possible "pollutants" before you start building, you can save yourself expensive renovations afterwards. The price differences are often a deterrent. However, if you then take a closer look, they are not as big as you might initially think. A direct discussion with the builder about the possible ecological alternatives therefore never hurts.
With sheep's wool in particular, you can already feel the direct difference during construction - no waste, pure nature, quick and easy processing - the best starting point for a Indoor climate to feel good.
