Pollutants in the indoor air - indoor air measurement with VOC sensors
On average, around 80% of the air that a person breathes in every day is indoor air. Indoor pollutants are usually invisible – they are gaseous substances or tiny dusts and particles. They can come from different sources. On the one hand, it can be fine dust that enters the room from the outside air, on the other hand, the source can be in the room itself, such as CO2, mold, formaldehyde, wood preservatives or plasticizers.
What is VOC anyway? Pollutants in the indoor air can affect health and well-being to different degrees when staying in buildings. Unpleasant smells in interiors, disorders of wellbeing and health complaints are often reasons for indoor air measurements in private and public areas. CO2 and VOC measurements are particularly relevant.
Sources of VOCs indoors
Was ist VOC?
Luftschadstoffe werden kurz als VOC bezeichnet. Die Abkürzung VOC (Volatile Organic Compounds) steht für flüchtige organische Verbindungen. Es handelt sich dabei um organisch-chemische Verbindungen des Siedebereiches von ca. 50 – 260°C. VOC sind praktisch jederzeit und überall in der Raumluft enthalten. Sind die Konzentrationen jedoch relativ gering, gelten sie als für den Menschen ungefährlich.
Sources of emissions for indoor pollutants are, for example, construction products or interior fittings such as floor coverings, wallpaper and wall paints, varnishes, adhesives, and furniture or heating systems.
Because the solvents contained evaporate and liquid or viscous products dry, the pollutants get into the room air. VOCs can also escape from solid products such as plastics, which contain many chemicals.
There is a risk of increased VOC concentrations in particular in the case of new construction or renovation or refurbishment of buildings due to the use of numerous VOC-emitting construction products.
VOCs can also outgas natural materials, such as wood, the terpenes can escape. They are also found in care, disinfection, cleaning and hobby products as well as in tobacco smoke. People, pets and microorganisms also excrete VOCs.
Effects and dangers of pollutants in indoor air
The different pollutants can reveal completely different effects. The health hazards range from unpleasant odors and irritation of the respiratory tract and eyes to acute poisoning and long-term damage.
These include damage to the nervous system, the triggering or intensification of allergies, cancer, genetic damage or impairment of reproductive capacity. Such symptoms are summarized under the term SBS (Sick Building Syndrome = building-related disease syndrome). Children, the elderly and people with a weakened immune system are particularly at risk from high levels of VOC.
Limit values for indoor air pollution
Neither in Germany nor in Europe are there any binding regulations for the requirements for indoor air quality. For this reason, the Committee for Indoor Standard Values of the Federal Environment Agency publishes recommendations in the form of reference and guideline values in order to be able to assess the contamination of indoor air with pollutants. Up to a corresponding guideline value I (RW I), no adverse health effects are to be expected after lifelong exposure to the substance in question. If the guideline value II is exceeded, health risks for sensitive room users can no longer be ruled out with sufficient probability.
These guide values apply to private indoor spaces, public areas and workplaces that do not deal with hazardous substances. The reference values, on the other hand, do not indicate any health risks, but express that a large part of the population is exposed to these substances to a comparable extent.
The mean total VOC concentration indoors should be below 0.3 mg / m³. For some substances or groups of substances, the Federal Environment Agency also derived guideline values based on health and toxicology. These generally have priority over a total assessment, which is why the corresponding guide values for individual substances should not be exceeded in these cases.
VOC measurement using VOC sensors in the ventilation system
VOCs should be taken into account with adequate, needs-based ventilation. Decentralized ventilation systems can optionally be equipped with VOC sensors for room air measurement, which can be used effectively for the needs-based control of ventilation systems or the measurement of air quality. VOC sensors detect changes in the VOC concentration in the room air. They do not react specifically to individual substances, but to VOCs in general and to gases such as hydrogen and methane. The information from VOC gas sensors can be used to regulate the operation of air cleaning or ventilation systems. If the VOC content in the room air increases, for example, an increase in ventilation is ensured.
Safety from VOCs in the interior
Complete avoidance of VOCs indoors is not possible. In order to keep the concentration as low as possible, low-emission products should be used for new construction, renovation or renovation of buildings, which are labeled with an environmental label such as the Blue Angel, and ventilation should be sufficiently intensive and long during the renovation work.
Intensive air exchange is generally the only way to reduce or avoid increased VOC concentrations. Regular and needs-based ventilation or a well thought-out ventilation concept play an important role in the quality of the indoor air.
Measurement of air qualityif the limit values are suspected
If there is any suspicion of an acute or chronic health risk from VOCs in the room air, a sampling and room air analysis should be carried out by an expert. After a VOC measurement, experts can usually determine the possible source of the pollution in the room air by inspecting the building and questioning the residents.
Short-term sampling is usually carried out for the determination of acutely and locally acting irritants, and long-term sampling is usually carried out for substances with systemic and chronic effects. Short-term measurements take a few minutes to a few hours, long-term measurements take from several hours to a few days or weeks.
Like any other measurement, a VOC measurement has a certain measurement uncertainty. In order to obtain the most accurate measured values possible, standard conditions should be created. This applies to ventilation conditions and temperature, for example.