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Michael: Every time you fly in an airplane, you're exposed to radiation from cosmic rays, which are high energy particles from outer space. Pilots and flight attendants are even classified by the center for disease control as "radiation workers." But, does that radiation make flying dangerous? Well, no. Even if you're a frequent flyer, you probably don't have anything to worry about.

See, we're all exposed to very small amounts of ionizing radiation every day, the kind that has enough energy to knock out electrons from atoms, so it can also break chemical bonds or damage DNA. But, your body's built to handle things going wrong in your cells by fixing them, or replacing any damaged cells with new ones.

All this background radiation comes from radon in the air and uranium and thorium in the soil. You even have some radioactive carbon-14 and potassium-40 inside your body, like all living things on Earth. Plus, you're still exposed to cosmic rays right here on the ground. When you fly, you're just exposed to more since there's less atmosphere above you.

Around the world, all this background radiation gives people an average annual dose of 2. 5 millisieverts, that's one of the units used to describe radiation. In the U.S. , it's more like 3 millisieverts per year. The international commission on radiological protection recommends that you keep your annual dose, beyond all that background stuff, under 1 millisievert.

To put that in perspective: you'd have to fly back and forth from New York to London for around 200 hours to reach that number. But, going a little over isn't necessarily dangerous. Most pilots and flight attendants have recommended dose limits of 20 millisieverts per year or 6 millisieverts per year if you work in the EU.

And, the risk of cancer is only thought to increase with doses of around 50 to 100 millisieverts per year, which is way above any exposure from flying home a couple times. Some studies suggest that flight crews have an increased risk for some cancers and reproductive disorders. Like one 2009 study from the National Institute of Occupational Safety and Health, showed that pilots with more flight experience had more chromosomal translocations in their DNA.

This is basically when parts of your chromosomes switch places when they shouldn't, and it's widely-accepted as a sign of exposure to ionizing radiation and some risk of cancer, especially leukemia and lymphoma. But, there are also studies that suggest flight crews don't face any increased health risks and just be aware of how much they're working if they're pregnant. So, science is still working on this one, but as a passenger, you've got nothing to worry about.

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preview of "Do Cell Phones Cause Cancer?"
Michael: I mean, you're holding a device that emits radiation right next to your brain. Terrible idea, right? Well, no.