German Committee on Indoor Air Guide Values | Umweltbundesamt

German Committee on Indoor Air Guide Values (AIR)

Indoor air is a significant chemical uptake pathway. To assess indoor air quality in public and private buildings, the German Committee on Indoor Air Guide Values (AIR) sets health-based guide values as well as hygienic guide values that enable a health-related assessment of substance concentrations in indoor air. The AIR also derives risk-related guide values for selected carcinogenic chemicals in indoor air. Members of the AIR are experts from federal states and federal governments in Germany who were appointed by the Working Group of the Highest State Health Authorities (AOLG). Further experts may be appointed as necessary.

The office of the AIR has been established at the German Environment Agency in Section II 1.2 "Toxicology, Health-related Environmental Monitoring".

Definition of 'indoor environment'

The German Advisory Council on the Environment (SRU) defines indoor environment as:

• dwellings with living rooms, bedrooms, hobby rooms, exercise and basement areas, kitchens and baths
• working areas in buildings which are not subject to the Ordinance on Hazardous Substances (GefStoffV), e.g. offices.
• spaces in public buildings (hospitals, schools, day care centres, sports facilities, libraries, restaurants, theatres, cinemas, and other public event venues)
• the interior of motor vehicles and public means of transport.

Indoor air guide values

The average person in Central Europe today spends 90 per cent of their time indoors. We breathe anywhere between 10 and 20 m3 of air per day, depending on our age and how active we are. The indoor air we breathe can contain a variety of pollutants that can affect our health. Therefore, it is important to be able to make a health-risk assessment of indoor air quality. Indoor air guide values are derived for this purpose.

The methods applied by the AIR to derive indoor air guide values are published in various principal papers in the Federal Health Gazette (Bundesgesundheitsblatt).

The AIR derives two indoor air guide values for the purpose of health risk assessment:

Indoor air guide value I (precautionary guide value) describes the concentration of a substance in indoor air for which or below which, according to current knowledge, adverse effects on health are not to be expected even after a lifetime of exposure.

At values above Indoor air guide value I, however, precautionary action must be taken. Measures to minimise the concentrations of the pollutant in indoor air should also be taken. Indoor air guide value I can serve as a remediation target value.

Indoor air guide value II (hazard guide value) is an effect-related value, based on current toxicological and epidemiological knowledge of a substance’s effect threshold. It represents the concentration of a substance in indoor air at and above which immediate action is required. At concentrations above these levels, harmful effects on human health cannot be ruled out with sufficient certainty. Guide value II correlates to the building codes of the federal states in Germany, which stipulate that structures must be designed to prevent hazards due to chemical, physical or biological impacts.

In 2022, the Federal Ministry Republic of Austria for Climate Action, Environment, Energy, Mobility, Innovation and Technology included the indoor air guide values derived from the AIR in their guideline for evaluation indoor air.

AIR Guide values I and II for indoor air pollutants

Hygienic guide values for indoor air

Hygienic guide values are determined when practical experience has demonstrated simultaneous increase of the likelihood of complaints and adverse health effects with the concentrations of an indoor air pollutant, but for which the state of knowledge is lacking to derive a toxicologically based indoor air guide value only. The following hygienic guide values were established for carbon dioxide, carbon monoxide and particulate matter (PM2.5).

Hygienic guide values for indoor air

Because indoor air can contain numerous organic compounds, the former Ad hoc Working Group on Indoor Air Guide Values (IRK/AOLG) had proposed benchmarks for the evaluation of volatile organic compounds (⁠VOC⁠) in relation to indoor air quality by applying TVOC values (Total Volatile Organic Compounds). However, the toxicologically derived indoor air guide values take precedence over the TVOC scheme.

Indoor air guide values for TVOC in indoor air

Risk-related guide values for carcinogenic substances in indoor air

Indoor air measurement data on the presence of a chemical in indoor air is required for a health assessment of cancer-causing substances (carcinogens). This data is recorded as a 95th percentile (reference value) and reflects what is called the background concentration of the substance in indoor air. Toxicological and/or epidemiological data on the exposure-risk relationship are also required. It is important to know the underlying effect mechanism of the carcinogenic substance. If an exposure-risk relationship study can be identified, the indoor air concentration of the carcinogen that is associated with a theoretical cancer risk of 10-6 after lifetime exposure must be identified. The concentration corresponds to one case of disease per 1,000,000 people based on lifelong exposure to the calculated concentration of the pollutant. This calculated concentration is compared with the current reference value from the available indoor measurement data. If the concentration derived from the exposure-risk relationship is above the current reference value, it is used as the risk-related guide value for the assessment. If the concentration of the reference value is linked to a theoretical risk higher than 10-6, then a provisional risk-related guide value is set based on the indoor air reference value.

Risk-related guide values for indoor air

Odour guide values for indoor air

The occurrence of unusual or unpleasant odours in indoor air can raise concern among occupants about exposure to indoor air pollutants with potential health effects. Complaints about an odour annoyance are often a reason for indoor air measurements. For the assessment of the plausibility of complaints about odour annoyance, the German Committee on Indoor Air Guide Values (AIR) provides so-called odour guide values (OGV) for various odour-relevant indoor air pollutants.

When an OGV is reached or exceeded, a concept of graded measures is recommended in order to minimise the odour exposure. If measures have been implemented to reduce odour annoyance, the success or failure of the measures is evaluated solely by the fact whether complaints about odour annoyance continue to exist.

The AIR points out that the table with the current OGV on this website is always valid, as it is updated in the context of new scientific and analytical findings. If an exceedance of indoor air guide values or risk-related guide values also occurs in the course of an indoor air measurement, the AIR points out that measures according to these concepts must be applied with priority.

The OGV are not suitable for a release measurement. The comparison of measurement results with OGV is only justified in cases where occupants have expressed a complaint about odour annoyance. An objective method for investigating the hedonic of an odorant, i.e. whether the odour is pleasant or unpleasant, is provided by the method of polarity profiles (VDI 3940/Sheet 4, 2010). This examination is usually done with selected and trained test persons. However, the assessment of the test persons does not necessarily reflect the odour perception of the affected occupant. Depending on the situation or based on individual experience, even an odour that most people find pleasant can be extremely annoying to some people. In addition, objective data on hedonics are available for only a few odorants. Therefore, hedonic was not explicitly considered when OGV were established. However, the hedonic is implicitly included because the concept of OGV is only applied when complaints of odour annoyance are raised.

The AIR is not aiming to create odour-free rooms. The concept is used to evaluate indoor air measurement results when the reason for the measurement were complaints about odour annoyance. For this reason, the AIR uses an intensity level of 3 (distinct odour) as a basis for deriving the OGV.

Minutes of AIR meetings

The minutes of AIR meetings are published only in German on the UBA website. Please note that the finalised minutes of a meeting are only approved at the subsequent meeting of the AIR.