• Question: Is standing next to your microwave oven while it's heating up your food dangerous?

    Asked by mallika54321 to Mark, Matthew, Mike, Paul, Sabina on 12 Mar 2014.
    • Photo: Paul Coxon

      Paul Coxon answered on 12 Mar 2014:


      No. Modern microwave ovens are perfectly safe.

      They work by bombarding the food inside with electromagnetic (EM) radiation with frequencies of around 2.45 GHz. In this frequency range, the charged water molecules within the food become excited and rotate backwards and forwards in the alternating electric field part of the EM wave. This action generates heat causing the food to heat up.

      Because microwaves don’t have flames or heating elements as in conventional ovens, the outside of the microwave doesn’t get hot and is safe to touch. The inside is made of metal, forming what is known as a ‘Faraday Cage’ which traps the microwaves safely, preventing them leaking out. The glass window on the door has a metal grill embedded within it. The holes in the grill are usually only a couple of millimetres across, which is much smaller than the wavelength of microwave radiation (12.2cm) trapping it in the cooking chamber, but large enough for visible light to escape so you can see inside.

    • Photo: Matthew Malek

      Matthew Malek answered on 12 Mar 2014:


      Nope. If your microwave oven is functioning properly, the microwave radiation is contained within and poses no danger to you.

      There could be some health risk if your microwave starts to “leak” radiation, possibly due to parts of the case or the door wearing out. If this happens, it will also heat your food less efficiently.

      If you are concerned that your microwave is leaking radiation, there are quite a few creative ways that you could check. Four of them are outlined on this nifty webpage:
      http://www.wikihow.com/Check-a-Microwave-for-Leaks

      When it comes to microwave ovens, the bigger dangers are in grabbing a bowl that is too hot… or in eating too much at once! ;-D

    • Photo: Sabina Hatch

      Sabina Hatch answered on 13 Mar 2014:


      I used to worry the same thing! But as long as you do not jar the door open and the metal casing is in good condition, then the microwaves cannot penetrate through the metal and are absorbed/reflected. You should be safe 🙂

    • Photo: Mark Jackson

      Mark Jackson answered on 14 Mar 2014:


      While an undergraduate I had a summer job at NASA building microwave ovens. NASA was interested in microwaves because they can heat objects much quicker than conventional ovens, are more energy efficient, and can focus their energy at specific locations in the object – including the inside!

      First let’s remember how microwave ovens work. Recall that microwaves are just electromagnetic radiation which are tuned to have the same frequency – 2.45 GHz – as the rotational frequency of a water molecule (in other words, the amount of time for a water molecule to flip around). As the microwave goes up and down, it becomes slightly positive or negative, and pulls and pushes the water molecule to spin around. Since they are at the same frequency they are precisely in resonance and the molecule keeps flipping around over and over, generating a lot of heat.

      This is fine for your food but not good for you, since it could lead to severe burns. For ‘experimental’ microwave ovens like the ones I was building there is a danger in case the microwaves escape. But any commercially available microwave oven should be perfectly safe, and you can stand next to it without worrying.

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