Microwave ovens

Microwave ovens use high-frequency electromagnetic fields with a frequency of 2.45 gigahertz to heat food up quickly.

These common household appliances operate at a power ranging from approximately 100 to 1,300 watts. The high-frequency fields are produced inside the appliances.

microwave oven

Shielding

Shielding measures ensure that, during operation, only very weak radiation passes from the inside of the device to the outside. A redundany technically guarding ensures reliable deactivation of the appliance as soon as the door is opened.

Despite good shielding, a small quantity of leakage radiation occurs in the vicinity of the mesh screen and the door. The appliance specifications therefore define an emission limit of 5 milliwatts per square centimeter (5 mW/cm2 = 50 W/m2) at a distance of 5 centimeters from the surface of the device.

Measurement results

The BfS has carried out comprehensive measurements on microwave ovens. The results of the measurements taken in November 1997 can still be considered valid, as there has been no significant change in the technical manner in which microwaves operate in recent years.

On average, the level of leakage radiation was 1% of the specified limit value ) at a distance of 5 centimeters from the surface of the device. These results were found on both old and modern commercially available appliances. The intensity of the high-frequency fields falls rapidly with increasing distance from the appliance. At a distance of 30 centimeters, for example, some 5–10% of the microwave intensity measured at the appliance surface is still present. At a distance of 1 metre, this value has fallen to between a thirtieth and a hundredth.

No danger to health from appliances in perfect technical condition

Appliances that are in perfect technical condition therefore do not pose a danger to health even for people in particular need of protection, such as pregnant women or infants.

If defects are observed, e.g. if there are visible mechanical changes to the door or signs of wear, it is recommended that the appliances be inspected by the service department and that, if necessary, the defects be rectified or defective appliances be replaced.

Heating food in the microwave oven is no more harmful than conventional methods of preparation

The different time and temperature characteristics of microwave heating compared with conventional heating methods can have specific effects on foods. Failure to adhere to the special cooking guidelines for microwave ovens can lead to overheating of foods or the inadequate elimination of germs due to insufficient heating. If the cooking guidelines are adhered to, however, the changes in nutritional value appear to match those produced by conventional heating. Accordingly, the microwave treatment of foods is no more harmful than conventional preparation methods (see BgVV-Heft 11/1997: L.I. Dehne, D. Früh, R. Matthes, G. Naumann; Mikrowellengeräte im Haushalt - Eine Verbraucherinformation (Microwave appliances in the home – information for consumers) in German only).