Since the eighties, a new disease has become part of the medical world, the so-called sick building syndrome. This primarily (but not only) refers to chemical pollutants from building materials, furniture and furnishings, but also from care and cleaning products, which pollute the indoor air within a building and are inhaled by the inhabitants and visitors and can lead to health complaints.

The list of chemical pollutants is long (more than 450 different substances are nowadays in parts examined indoors) and new pollutants are added every year. To depict the different substances individually would exceed the scope of this article, so only the most important pollutant groups will be described in more detail.

In general, a distinction must be made between volatile (VOC) and semi-volatile pollutants (SVOC). The first are examined via air samples, while the latter are analysed using dust samples.

The volatile pollutants VOCs (volatile organic compounds) include the classic solvents (benzene, toluene, xylene, the so-called BTX), halogenated substances (such as PER or perchloroethylene, generally used as fat removers), but also fragrant terpenes and preservatives such as glycol ethers and isothiazolinones. In addition, there are aldehydes including the well-known carcinogenic formaldehyde, which is however by no means the only aldehyde. Recently siloxanes have joined the list as new volatile pollutants.

The semi-volatile pollutants found inside buildings are biocides and pyrethroids, used to ward off mould or insects in wood, leather, (wool) carpets or as insect sprays, electric evaporators or moth repellents. Neurotoxic brominated (PBDE) and organophosphorus flame retardants are not only used as flame retardants in computers, wood or polyurethane foams, but also as plasticizers or in cleaning and care products due to their “shiny and non-slip” properties (TBEP). PAHs from tar oil preparations and PCBs from expansion joints, as well as asbestos are well known “old” pollutants largely used in the building sector in the past.

Table of the most important pollutants found indoors:

While many of the volatile pollutants gradually “fly away” after the completion of the building and the pollution of the indoor air thus decreases, this is usually not the case with the semi-volatile pollutants. Even after decades, the contamination of the indoor air is almost like it was on the first day.

Hormone-like pollutants such as plasticizers, PCBs, bisphenol A, PBDEs, as well as various biocides and heavy metals are called “endocrine disruptors” and act either like male hormones or like female pseudo-oestrogens. Such pollutants negatively impact human health mainly during sensitive life stages, for example during puberty. However, the impact can also be before birth (prenatal) on the foetus, or the embryo immediately after fertilization.

In addition to building-related pollutants, there are also pollutants in food, cosmetics, medical products and household utensils. These include numerous heavy metals.

Table of the most important heavy metals impacting health:

From a health point of view, it should be noted that most pollutants are lipophilic therefore fat-soluble. For this reason, they accumulate in the adipose tissue of humans. In addition, especially the semi-volatile, but also some volatile pollutants are persistent, i.e., extremely long-lived and bioaccumulative, i.e., they accumulate in the human body, more precisely in the fatty tissue of humans. As a result, after decades of exposure, it is no longer sufficient to renovate and to remove the source pollutant, but the fat deposits must also be detoxified. The health burden is considered endogenous, i.e., poisoning from the inside out.

For most pollutants, there is no need for a toxicologically high dose to cause health problems. Rather, it is the low concentrations over a long period of time (experts in environmental medicine call it chronic low-dose-long-time exposures) which can lead to partially irreversible health damage over years and decades.