S Ramstad, D Bratlid, T Christensen, A Johnsson

Abstract

The 50 Hz magnetic flux densities created by some typical equipments at a neonatal intensive care unit were measured. A detailed study was made of the magnetic flux densities in an incubator, two types of radiant warmers, a heated water bed and a phototherapy unit (BiliBed). The mean flux densities in an incubator was typically in the region 0.2 - 1 μT (maximum around 1.5 μT), for the radiant warmer less than 0.05 μT at the bed level and for the phototherapy unit 0.15-2.6 μT. Although the heating pad under the water mattress produced no fields, the control unit created levels up to about 2 μT at the patient position when located at the bed end. Compared to typical field levels found in residential houses the measured levels are stronger by two orders of magnitude. Moving the electrical control units away from the infants can strongly reduce the fields, as shown by the measurements.