Microwave drying

Microwave drying is becoming more and more common for repairs of moisture and water damage in apartment buildings. It is much faster to dry moist flooring and walls made out of concrete by using microwaves than compared with ordinary construction fans. If microwaves in connection with microwave drying are used incorrectly, they may cause injury. This is why the Swedish Radiation Safety Authority imposes requirements and exercises regulatory supervision in this area.

Microwave drying is a process that basically works in the same way as when we heat food in a microwave oven. The microwaves cease at the same moment as the drying machine or microwave oven is switched off.

The drying method is based on microwaves penetrating the moist material, where the microwaves are converted into heat. The moisture turns into vapour and is transported from the building using a fan.

The microwaves are produced by a magnetron inside the drying machine. Microwave ovens have the same kind of magnetron. The drying machine is placed up against the area with the moisture damage so that the machine will dry it effectively.

When microwave drying is taking place inside someone's home, information about this must be posted on the door.

Health risks

Microwaves emitted during microwave drying can be detrimental to health if the drying machine is used incorrectly. If people or animals are exposed to high levels of microwaves, this can quickly cause harmful heating of body tissues.

The tissues harmed by microwaves are often below the skin, where there are no sensory cells that could otherwise react to the excessive heat. However, the health detriment from microwaves that is most well known is cataracts. The cells in the lens of the eye are more sensitive to heat; also, the lens has no blood circulation that would otherwise help to cool down other tissues.

The companies in the microwave drying business are responsible for ensuring that drying equipment is managed properly and safely.

The Authority's requirements

The Swedish Radiation Safety Authority imposes requirements on parties that use microwaves to repair moisture damage. The Authority's aim is to protect the general public against harmful levels of microwaves. We check to ensure that microwave drying companies comply with regulations. Regulatory supervision for example includes on-site compliance inspections and checking the measurements performed by these companies.

Under our regulations, parties that work with microwave drying must:

  • Notify the Swedish Radiation Safety Authority about this activity
  • Have a good level of knowledge about how to handle the equipment and measure microwaves as well as the various potential risks attributed to microwave drying
  • Ensure that people and pets stay out of spaces where the microwaves exceed the limit
  • Ensure that spaces where the microwaves may exceed the limit are locked or are in some other way inaccessible to unauthorised persons
  • Post a sign with symbol and warning outside the locked space
  • Regularly measure levels in nearby rooms
  • Record measurement results in an operating journal.

It is prohibited to commence operations involving microwave drying without confirmation issued by the Swedish Radiation Safety Authority that the above notification has been received.