We've heard about radiation from the damaged nuclear reactors in Japan reaching American shores. Experts say so far there is no reason to worry, and point out that we encounter radiation every day. Where and how? NPR's Renee Montagne posed that question to Peter Caracappa, a radiation safety officer and rofessor of nuclear engineering at Rensselaer Polytechnic Institute in Troy, New York.
MONTAGNE: How many things emit radiation?
Dr. CARACAPPA: Well, radiation and radioactive material is a part of nature. So everything that's living has some amount of radiation coming from it — a very small amount. Plus there's radiation in the ground and the air.
So the extremes are uranium in the soil to bananas?
By the way, why do bananas have radiation?
Bananas have a lot of potassium. And a small amount of potassium naturally is called potassium 40, which is radioactive.
What's the difference between radiation that's harmful and not harmful?
Well, the term radiation can apply to a lot of different things. But the harmful radiation is ionizing radiation. It has enough energy that it can make chemical changes in material. We could get ionizing radiation from an X-ray, for example. It's the kind of radiation that causes cancer.
The broader definition of radiation includes a lot of things that we call non-ionizing radiation. That includes everything like radio waves and visible light and your microwave.
So what then is the largest contributor of ionizing radiation?
For the natural sources of ionizing radiation, actually the biggest chunk of that tends to come from radon, which is a radioactive material that is present in the air. It can become a concern when it builds up in low-lying areas of homes like basements.
So is that worth being vigilant about in terms of trying to protect ourselves from radon?
The general principle of radiation protection is that radiation should be kept as low as reasonably achievable. So the idea behind this is that any small amount of radiation carries with it some comparably small amount of risk. So for radon in basements, there's some easy fixes that allow you to reduce the radon exposure. If it's easy to do, then less is better.
Would it be fair to say that most people do not need to worry about the danger of being exposed to radiation?
I would say that the everyday exposure to radiation that we encounter contributes an extremely tiny risk to our life or to our health compared to all of the other risks that we encounter in our day-to-day life.