German Committeeon Indoor Guide Values

An ad-hoc working group was set up in December 1993 to derive guidelines values for indoor air. Its members are delegates from the Indoor Air Hygiene Commission (IRK) and the permanent working group of the Highest State Health Authorities (Arbeitsgemeinschaft der Obersten Landesgesundheitsbehörden, AOLG), formerly known as hospital commission study group of governing medical officials (AGLMB).

In accordance with a decision of the Highest State Health Authorities from March 10th, 2015 the Ad hoc Working Group for Indoor Air Guide Values was renamed to the German Committee on Indoor Guidelines.

How is ‘indoor environment’ defined?

The following definition of ‘indoor environment’ was established by the German Council of Environmental Advisors: "Indoor environments are 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. It includes spaces in public buildings (hospitals, schools, kindergardens, sports facilities, libraries, restaurants, theaters, cinemas, and other public event venues), and the interior of motor vehicles and public means of transport."

Whereas limit values as per the Hazardous Substances Ordinance are in effect for work areas where hazardous substances are handled, they do not apply to the indoor spaces listed above. For example, formaldehyde pollution in the air of an office which occurs through emissions from furniture containing chipboard is considered similar to comparable pollution of living rooms and not seen as workplace pollution, e.g. in the chemical industry.

Guide values I and II

Indoor air guide values for individual substances are being developed by an ad-hoc working group of members of the Federal Environment Agency's Indoor Air Hygiene Commission (IRK) and the Permanent working Group of the Highest State Health Authorities (AOLG), which are founded on a basic scheme published in the Bundesgesundheitsblatt in 1996. In accordance with this, two guide value categories have been established.

Guide value II (RW II) is an effect-related value based on current toxicological and epidemiological knowledge of a substance's effect threshold that takes uncertainty factors into account. It represents the concentration of a substance which, if reached or exceeded, requires immediate action as this concentration could pose a health hazard, especially for sensitive people who reside in these spaces over long periods of time. Depending on how the substance concerned works, guide value II may be defined either as a short-term value (RW II K) or a long-term value (RW II L).

Guide value I (RW I) represents the concentration of a substance in indoor air for which, when considered individually, there is no evidence at present that even life-long exposure is expected to bear any adverse health impacts. Values exceeding this are associated with exposure that is undesirable for health reasons. For the sake of precaution, there is also need for action in the concentration range between RW I and RW II. RW I can act as a target value during clean-up efforts, which should be undercut rather than merely complied with. Guide value I is derived from guide value II through the introduction of an additional factor based on convention.

The guide values apply for individual substances and provide no indication of any possible combined effects with different substances. Up to the end of 2006, the following guide values were established by the IRK/AOLG ad hoc working group

Guide values (I and II, in milligrams per cubic meter of air) for the concentration of specific substances in indoor air

Volatile organic compounds

In order to account for the fact that indoor air contains a great many organic compounds and relatively few guide values have been established, the IRK developed evaluation standards for assessing indoor air quality by using the sum of volatile organic compounds (TVOC). However, these TVOC values as sum values could not be derived from the basic scheme. To clarify uncertainties which resulted from the derivation, ranges of concentration were applied rather than individual numerical values. Therefore, a daily stay, at least in the short term, is reasonable in rooms with TVOC concentrations of 10-25 mg/m ³ (such concentrations may arise during home improvement work). In rooms intended for longer-term residence, the TVOC value in the range of 1-3 mg/m ³ should not be exceeded. Ideally, TVOC concentration in indoor rooms should reach a maximum long-term average of 0.2-0.3 mg/m ³ or lower if possible.