According to current scientific knowledge, the protection of the health of the population is also ensured under permanent exposure by compliance with the limit values set in the Twenty-sixth Ordinance Implementing the Federal Immission Control Act (Ordinance on Electromagnetic Fields - 26th BlmSchV). However, apart from proven health effects there exists scientific evidence of health risks at low field intensities. In order to account for this uncertainty the Federal Office for Radiation Protection demands precautionary measures.