Regulating Indoor Air

The possibilities to reduce indoor air pollution comprise source control, dilution and the setting of limit values for indoor air pollutants. While emission standards, voluntary agreements, and even bans are elements of the first option, the dilution approach includes ventilation standards and air cleaning devices. In contrast to the situation for outdoor air and the air at work places, setting air quality standards does not seem to be the appropriate way to reduce indoor air pollution. Rather, the use of guideline values for indoor air pollutants is recommended. Guideline values may be set two at a time, one defining a level of hazard for immediate action, the other a target concentration for the future. The example of tetrachloroethene is chosen to illustrate the applicability of the concept in practice.