In a recent study, Carnegie Mellon University (Pittsburgh, USA) in cooperation with the National Oceanic and Atmospheric Administration (NOAA, USA) focused on volatile organic compounds (VOCs ) and compared detailed chemical measurements of outdoor air with indoor air quality data in Los Angeles. They came to the conclusion that only about half of the air pollution in the USA can be attributed to traffic-related emissions particulates. VOCs from industrial and consumer products are responsible for the other half.
Definition: Volatile organic compounds
Volatile organic compounds (VOCs) is the collective term for all organic, i.e. carbon-containing, substances that evaporate (i.e. volatilise) quickly due to their low boiling point. Even at relatively low temperatures, for example at room temperature, they are present as a gas, but they can also be in vapour form - i.e. both liquid and gaseous. The most common groups of substances include hydrocarbons, aldehydes, alcohols and organic acids.
The World Health Organisation (WHO) divides the group of VOCs into the following subgroups according to their boiling point and thus their respective volatility:
- < 0 bis 50… 100°C → Very Volatile Organic Compound (VVOCs, sehr flüchtige organische Verbindungen)
- 50...100°C to 240...260°C → Volatile Organic Compound (VOCs)
- 240...260 to 380...400°C →Semi-Volatile Organic Compound (SVOCs, low volatile organic compounds)
- > 380°C → Particle-Bound Organic Matter (POMs, particle-bound organic matter/ organic compound associated with particulates)
However, it is difficult to give an exact definition for VOCs. Some definitions are based on vapour pressure, others on the photochemical reactivity of the compounds and thus their importance as precursors for the formation of ground-level ozone. In addition, some definitions explicitly exclude certain organic substances from the group of substances. For example, NMVOC (Non-Methane Volatile Organic Compounds) excludes methane (CH4).
The sum of all VOCs in indoor air is also referred to as TVOCs (total volatile organic compounds). The creation of TVOCs as an indicator variable is what makes it possible to evaluate the VOC concentration in a room in the first place. Nevertheless, this artifice remains problematic, as the combination of different chemical compounds cannot do justice to the complexity of reactions and effects. For this reason, it also remains difficult to set limit values for TVOC.
Sources of VOCs
Biological sources of volatile organic compounds include decay, degradation and plant metabolic processes. These compounds accumulate in the outdoor air. The same applies to VOCs from technical processes such as incomplete combustion (e.g. car exhaust) or certain commercial and industrial activities.
In indoor spaces, VOCs often arise from outgassing of building materials and the entire interior decoration. These include floors, walls and ceilings, but also paints, varnishes and adhesives, as well as furniture, home accessories and often toys. In addition, there are numerous cleaning, care and hobby products as well as flame retardants, tobacco smoke, the preparation of food and finally the metabolic processes of the occupants.
Since Europeans spend most of their time indoors, the volatile organic compounds present there are of greater importance in terms of health and performance.
Health effects: Irritation, fatigue, headache
An increased VOC concentration first shows itself through an altered perception of odours and tastes. In addition, irritation of the mucous membranes and eyes may occur. The higher the concentrations rise, the stronger these symptoms become. In addition, fatigue and headaches may also occur.
If these symptoms usually decrease after leaving a stressed room and especially after a longer absence and increase again when re-entering, this can also be the so-called sick building syndrome (SBS). This syndrome describes the occurrence of certain symptoms and illnesses to which no specific causes can be assigned. However, it is characteristic that they are associated with staying in a building.
There are currently too few conclusive studies on the long-term effects of exposure to volatile organic compounds. However, experts suspect a connection between VOCs and the increase in allergic reactions, especially in small children and infants. Constant exposure to fragrances can also trigger allergies. Furthermore, experts estimate the toxic long-term effects of many of these substances as potentially carcinogenic, mutagenic and reproductive.
Improve air quality
To keep exposure to volatile organic substances as low as possible, the products and materials chosen should be low-emission. The Blue Angel eco-label, for example, is a good indication of such products. For construction and renovation work, the AgBB evaluation scheme (defined by the Committee for Health-related Evaluation of Building Products) helps to find materials that are particularly low in VOCs.
Since the composition of TVOCs in a room varies as much as the toxicity of the individual substances, it is difficult in this case to make concrete and generally valid offers of help. Therefore, it is necessary to continuously monitor the pollutant concentration in living and working spaces. This is the only way to reliably detect the sources of VOC emissions. It is then also decided to what extent the measured substances (e.g. those produced during cooking) are comparatively harmless or whether they are toxic and thus acutely hazardous to health.
(Image: Pixabay / Willfried Wende)
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