Article 74 Radon in dwellings and buildings with public access 1. Within the action plan referred to in Article 103, Member States shall establish national reference levels for indoor radon concentrations, which shall not exceed (as an annual average): (a) 200 Bq m-3 for new dwellings and new buildings with public access; (b) 300 Bq m-3 for existing dwellings; (c) 300 Bq m-3 for existing buildings with public access. In specific cases where the occupancy time is low, a reference level of up to 1 000 Bq m-3 can be set. 2. Under the national action plan, Member States shall (a) identify existing dwellings exceeding the reference level and to encourage radon-reducing measures in existing dwellings where the reference levels are exceeded; (b) ensure that radon measurements are carried out in buildings with public access within radon-prone areas. 3. Member States shall establish specific building codes to prevent radon ingress from the soil and, as specified in the national action plan, from building materials, and require compliance with such building codes, in particular in radon-prone areas, so as to avoid radon concentrations exceeding the reference level for new buildings. 4. Member States shall provide local and national information on prevailing radon concentrations, on the associated health risks and on the technical means available for reducing existing radon concentrations.deleted