A basic distinction is made between type 4 allergens, which cause a T-cell response, and type 1 allergens, which cause an immediate allergic reaction.
The common type 1 allergens that are important in buildings include pollen that is carried into the building from the outside area, in particular pollen from birch, alder, hazel and less allergenic tree species such as beech and oak. This is followed by a detailed assessment of the outdoor area and advice on planting plans.
There are clear lists of contact allergens from the German Society for Contact Allergy (DKG). However, the listed ingredients have different meanings depending on which of the materials they occur in. For example, a rubber ingredient on the backing material of a carpet is not a problem, whereas a volatile preservative in the backing material of the carpet may well be significant in the room air. The same applies to the sheathing of plastics, e.g. cables. Particularly when these become warm under electrical load, considerable evaporation of plasticizers can occur, which can be harmful to the interior.