Radiation Is Everywhere. But It’s Not All Bad

Most people interpret radiation as a bad thing—but it isn’t always. In fact, radiation is a very normal phenomenon. For now, let’s just say that radiation is when an object produces energy. When a material is radioactive, it emits energy either as particles or electromagnetic waves. The particles are usually things like electrons or atoms. The waves could be in any region of the electromagnetic spectrum. Since your Wi-Fi produces electromagnetic waves, technically your home access point is a source of radiation. So is that light bulb in the ceiling. Actually, even you are a source of radiation in the infrared spectrum, due to your temperature.

However, most people don’t think of radiation that way. What’s commonly called “radiation” is actually a special type: ionizing radiation. When an object produces ionizing radiation, it emits enough energy that when it interacts with other materials there’s a chance it could free an electron from its atom. This electron is then free to interact with other atoms, or maybe just wander off into empty space. But no matter what the electron does, once it gets away from its original atom, we call that ionization.

Ionizing radiation was discovered by accident. Before digital smartphones, when people took pictures on film, the basic idea of photography was that when film was exposed to light, it would cause a chemical reaction that would reveal a picture when the film was developed. Then in 1896, French physicist Henri Becquerel discovered radioactivity when he realized that uranium salts produced an effect on otherwise unexposed photographic film that was still in its wrapper. Somehow the uranium produced an effect similar to light, but unlike the light, it could pass through the paper wrapping.

It turns out that uranium is naturally radioactive, and this was a type of ionizing radiation. Uranium produces electromagnetic waves in the gamma spectrum. Gamma radiation is similar to visible light when it interacts with film (thus exposing it), but it’s different from visible light in that it can pass through paper.

You might not directly use uranium in your everyday life, but you will indeed encounter ionizing radiation—at safe levels—in many different applications. For example, smoke detectors use a radioactive source to detect smoke in the air. A radioactive source produces charged particles (alpha particles, in most cases) that ionize the air inside the detector, which in turn creates an electric current in the air. If tiny particles of smoke get inside the detector, it blocks this electrical current. Then the detector sends a signal to make an ear-piercing noise so that you know there’s a fire—or maybe that you burnt your dinner on the stove.

Eighteen percent of the electrical power in the US comes from nuclear power plants, and they obviously produce ionizing radiation. Medical x-ray images can produce ionizing radiation. Some ceramic dishes are coated in a uranium-based paint—yup, that produces radiation. Technically, bananas are radioactive, due to their comparatively large concentration of potassium. Ionizing radiation could even be from outer space—we call these cosmic rays.