Ventilation strategies in the case of polluted outdoor air situations.

Outdoor air pollution can have a bearing on the effectiveness of indoor air and the quality of ventilation. There is a pressing need to reflect on the potential type and effect of occurrences (e.g. smog, or chemical accidents) and to develop technical, operational and organisational measures which must be taken with mechanical ventilation units in the case of polluted outdoor air situations. A polluted outdoor air situation is present when a ventilation process leads to the intake of pollutants in the interior and to the enrichment of these pollutants to an unacceptably high concentration. The measures to recommend will primarily depend on the specific outdoor air situation, type and quality (leaks) of the building and the type of mechanical ventilation unit in use.