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What is formaldehyde?

Published 07.10.2021


Following the introduction of the general term of VOCs this article explores an organic compound called formaldehyde. Although being recognized as carcinogenic, it is widely used as a building block for complex compound synthesis thus ending up in commercially available paints, varnishes, wooden products and everyday items.

To understand better the nature of this invisible indoor pollutant, the following chapters will explore:

  • What is formaldehyde - definition, properties and application;
  • Paint industry and formaldehyde;
  • The impact of formaldehyde on the health and wellbeing of humans and the environment.

Consumer knowledge regarding formaldehyde use.

What is formaldehyde?

Formaldehyde (also called methylene oxide, methyl aldehyde, oxomethane, oxymethylene) is a gaseous organic compound consisting of hydrogen, oxygen and carbon molecules. It can be found in nature as well as in man-made and industrial products. We are constantly in contact with formaldehyde around 1-2 (ppm). Namely, it is naturally in our blood as well as in the breath we exhale. Even primitive organisms have used formaldehyde to synthesize more complex molecules.

Despite the natural occurrence formaldehyde is toxic if not taken care by / its inherent toxicity has been controlled by certain enzymes that convert it into format which is less reactive and less toxic, becomes toxic exceeding certain level of exposure above which humans should not be exposed (DNEL). According to the EU legislation, the worker long-term DNEL for inhalation is 0.3 ppm (0.37 mg/m3) and the worker short-term DNEL for inhalation is 0.6 ppm (0.74 mg/m3) (o)

Formaldehyde: physical and chemical profile

Chemical formula


Molecular mass

30.03 g/mol

Relative vapor density

1.03–1.07 (air = 1)

Melting point

92 °C

Boiling point

19.1 °C


water, ethanol and chloroform


acetone, benzene and diethyl ether

Formaldehyde is a unique compound due to its applicability for synthesizing resins. About 60 % of all formaldehyde used in the EU is related to the manufacturing of different resins including phenolic resins (also known by trade name Bakelite®) and urea - formaldehyde resins, that have multiple desirable characteristics - they are hard, thermally and dimensionally stable, chemically resistant, fire resistant, while also having resistance against acids, solvents and water (g)(l). Formaldehyde is also a desirable ingredient due to its properties as a biocide (l).

Formaldehyde-based resins are used worldwide for the production of a wide variety of products and materials. The wood adhesive industry has the largest market share of phenolic resins in the world  and the coating industry has the sixth largest (h).

Paint and coatings industry uses phenolic resins as binders for paint products. These binders are polymers responsible for holding together pigments and forming a film on the surface. Namely, they are the base components of paints bringing all other paint ingredients together.

Formaldehyde source


Across the European Union 73 sites in 21 countries have integrated formaldehyde production in the manufacturing of formaldehyde-based resins and other chemicals. Largest producers by country are Germany with 12 sites and Italy with 10 sites (l).

Also noteworthy is the fact that the main sources of raw materials used in the manufacturing of formaldehyde are petroleum-based non-renewable resources. It means that the production process of formaldehyde is not sustainable. (j)

Formaldehyde impacts on environment

Formaldehyde is available in the environment due to both natural and human-induced activities.

In nature formaldehyde is released mostly through combustion of forests and volcanic activity as well as biomass decomposition processes, while human-induced formaldehyde release in the environment takes place through burning of fossil fuels, smoking and industrial activities involving manufacturing.

Formaldehyde is not considered an atmospheric or environmental pollutant due to different factors - it does not accumulate but is broken down quite fast, it also dissolves fast in aquatic environments and evaporates from soils.

With this being said, formaldehyde in large quantities in situ (locally) can cause harm to biosphere, animal and human well-being. Thus it is the responsibility of industries to properly treat their wastewaters as well as provide healthy indoor conditions for their workers. (b)

Being aware of the potential impacts of formaldehyde, the paint and coatings industry is also making a dedicated effort to seeking possible alternatives. One of them are the newest architectural coatings, which use acetoacetoxy chemistry to absorb formaldehyde emitted from household items.

Formaldehyde impacts on health

"Formaldehyde is definitely the most common and the best-known indoor air pollutant" states publication “Formaldehyde in the indoor environment” (c).

Exposure to formaldehyde primarily happens through breathing indoor air, where one of the main sources of off-gassing compounds are newly introduced building materials and consumer products, contributing effects lasting up to several months depending on humidity and temperature of the indoor environment. The impact of formaldehyde can still be present after years of lying trapped dormant in a material and by being exposed again during its renovation (b) (k).

As it can be seen in the Table 1, the health effects of formaldehyde depend on the compound concentration in the air, leading to effects ranging from skin, nose and eye irritation to breathing difficulties.

Formaldehyde exposure studies on animals also register tumor development that has led to numerous studies regarding cancer development in humans (e).

Currently the European Chemicals Agency has assigned to formaldehyde the status of carcinogenic substance. Namely, it can cause cancer in animals and humans, while also pointing to two additional properties of concern like susceptibility to be mutagenic, which means potential to cause permanent changes in genes (genetic information), and the above mentioned skin sensitizing properties which means allergic response related to the contact of chemical substance with the skin. Formaldehyde is toxic if swallowed as well as when inhaled (f).

Table no. 1

Concentration in Air (ppm)

Effect in Humans

Effects in Animals


no studies

bloody nasal discharge, pulmonary edema

11 - 59

no studies

nasal and eye irritation, nasal ulceration, change in pulmonary function, neurological effects, liver effects decreased body weight, decreased fetal weight, nasal tumors, reduced survival

6.0 - 10.9

nasal, eye, throat and skin irritation, headache, nausea, discomfort in breathing, cough


nasal and eye irritation, nasal ulceration, change in pulmonary function, liver effects, testicular effects, nasal tumors, reduced survival

2.0 - 5.9

nasal, eye and throat irritation, eczema or skin irritation, change in pulmonary function


nasal and eye irritation, throat irritation, change in pulmonary function, decreased body weight, enhanced allergic responses, neurological effects, liver effects, testicular effects

0.6 - 1.9

nasal and eye irritation, eczema, change in pulmonary function

change in pulmonary function, neurological effects

0.1 - 0.5

nasal and eye irritation, neurological effects, increased risk of asthma and/or allergies

change in pulmonary function, enhanced allergic responses, neurological effects


Resources for health and environmental impacts of formaldehyde:

Consumer knowledge

In order to purchase safe materials and work with these materials, consumers should take informed decisions regarding formaldehyde emission standards as well as its labeling.

According to the World Health Organization, the standard of formaldehyde emissions from a product cannot exceed 0.10 parts per million (ppm).

There are two labels that provide an information to the consumers about products emitting formaldehyde in a non-threatening dose (according to WHO standards) - the European E1 Standard and the GreenGuard certification, while OSHA Hazard Communication label provides information to the consumers about formaldehyde emission levels that exceed the WHO limits (m).

Standards  and  product labeling regarding formaldehyde emissions:

World Health Organization

European E1 Standard

GreenGuard® Environmental Institute Certification

OSHA Hazard Communication Standard

Below 0.10 ppm

Below 0.10 ppm

Below 0.05 ppm

Above 0.10 ppm

The most sensitive to formaldehyde emissions are chemically sensitive people, people with respiratory problems or asthma, newborns and babies, elderly people and pregnant women (m)(n).

To reduce formaldehyde indoor emissions:

  • Avoid products containing VOCs as well as formaldehyde-based resins and chemicals.

  • Make sure to ventilate rooms by opening windows and doors or introducing fans during the painting with formaldehyde resin containing paints and after the painting process is finished.

  • Purify indoor air with HEPA or other formaldehyde gas absorbing filters.

When experiencing formaldehyde exposure symptoms or unsure about indoor air quality because of moving into a newly renovated house or flat, or when working in a workplace with a lingering suspicious pungent chemical smell, it is advisable to perform a formaldehyde test using one of commercially available formaldehyde test kits (m).




Paint and coatings industry uses formaldehyde in the production of paint binder resins, contributing to formaldehyde off-gassing into the indoor environment and thus posing threats to human and animal health in cases, when the concentrations exceed 0.10 ppm.

Elaborate studies over the last 60 years have led to understanding about the health associated risks regarding alleviated formaldehyde concentrations in the indoor air, thus certain standards have been developed allowing consumers to take charge of their health and surroundings.

Although it is not possible to avoid formaldehyde altogether, it is possible to control it in  the indoor environment, such as your home  or workplace, by choosing paints and products that do not contain phenolic resins and other formaldehyde-based chemicals.

Sufficient information about the product labeling and manufacturer's product transparency policy can help consumers of the paint products to choose chemicals that do not pose significant health and environmental threats.


Author: written by Anse Romančuka, edited by Linda Kikuste



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