Aug 31, 2006

SCI-KIDS
Sci-Kids is a weekly column on science topics for children in elementary through middle school.
 
What should we do about the flood of radiation around us?

As good scientists, we should first categorize and list. What is around us? Hitting us? Passing through us?

The radiation in our environment is electromagnetic radiation, wavelike particles (or particlelike waves) of energy. Radio waves qualify. So do TV broadcast waves and satellite transmissions, such as Global Positioning System signals.

Cell-phone signals count, as do the little TV and DVD remote controls. One massive radiator in our kitchen: the microwave oven.

Everything we see is reflecting radiation in the visible spectrum. Emitters are things such as light bulbs, and the electric cooking surface of a range.

The sun is a huge emitter of radiation. It comes to us as visible light, infrared and ultraviolet. The visible light illuminates our world, the infrared heats our world and the ultraviolet can destroy skin cells -- causing skin cancer.

It is smart to know which forms of radiation are helpful and which are harmful. We must know how to protect ourselves against harmful radiation.

Electromagnetic radiation in its longest wavelength is radio waves. As wavelengths get shorter than radio and TV signals, they are called microwaves.

The radiation we feel from a hot fire, an oven or an iron is mostly infrared.

Above infrared is visible light, with shorter wavelengths still.

The shortest wavelengths of radiation are ultraviolet, X-rays and gamma rays, all harmful to humans.

Gamma rays come from space, formed within stars and the decay of radioactive isotopes. Gamma rays are responsible for many of the random changes in DNA the mutations that provide variation in our genes.

Should we worry about cell phones frying our brains? No. The power level is too low. Should we worry about leakage from the microwave oven? No. Microwaves are too long to pass through the tiny holes of the metallic window guard. Should we worry about overhead power lines? No. The 60-hertz radio waves they emit are low energy.

The real worries are sunburn (from UV-A and UV-B), bypassing the door lock on a microwave and X-ray overexposure.

Virginia's Science Standards of Learning cover radiation, beginning with safety standards, and in topics 6.3, PS-7, ES-13, and PH-10.

Walter Witschey is director of the Science Museum of Virginia.