A climatic chamber at the Department of Environmental and Occupational Medicine, Aarhus University, is modified with absorbing lining to dampen reflections from the walls. The climatic chamber is modified to make it a screened room to prevent external RF fields, and to some extent low frequency fields, to enter the chamber. Except for cables to the keyboard and screen there are no other electromagnetic radiators in the chamber. The study will be double blinded as any noise (acoustic and electric) related to exposure will be the same and the person responsible for exposure and exposure assessment will not be able to see each other. The only investigator knowledgeable about the exposure will have no contact with subjects and staff doing measurement. This double blinding will continue until the basic statistical analyses have been conducted.