Common Everyday Sources Of Radiation - Part 2 of 4 Parts
Part 2 of 4 Parts (Please read Part 1 first)
Airport scanners employ a specific band of the electromagnetic spectrum called the terahertz band. This band falls between infrared band and the microwave band. Terahertz radiation is almost complete blocked by human skin and is not thought to be very dangerous.
Flying in an airplane at thirty-five thousand feet exposes the passengers to radiation from space which is usually blocked by the atmosphere near sea level. This radiation consists of cosmic rays. There is great variation on the amount of such radiation encountered by passengers and even relatively high doses are a few percent of natural background radiation for a single flight.
Coal power plants emit a lot of radiation carried in the smoke from the stacks. There are traces of radioactive uranium and thorium in the coal that can become part of the ash that travels with the smoke. Alpha particles and gamma rays are emitted by uranium. The amount of radiation from ash is spread of a large area and poses little threat to health. On the other hand, the ash that does not get carried up in the smoke and the slag from the boiler do contain dangerous amounts of radioactive materials.
Thorium, potassium-40 and even depleted uranium have been used in the past to create colorful glazes in ceramics and well as color in glass. Alpha particles are the main type of radiation from these sources. There is a piece of glass from ancient Rome which contains uranium for color. Some older dinnerware was decorated by glazes containing radioactive elements.
Exit signs in buildings are designed to stay on if the electricity fails. They accomplish this by containing the radioactive element tritium which emits beta particles. Since the only health threat would be from ingesting tritium, unless you eat parts of an exit sign, you will be safe.
Fluorescent lights used in many large buildings, schools, shops and even homes often contain krypton-85 which is a radioactive isotope that emits beta particles and gamma rays. As long as they are carefully disposed of when they burn out, they are safe to use.
Some smoke detectors contain the radioactive isotope americium-241 which emits alpha particles. It is surrounded by foil and other materials that block much of the radiation. Detectors are usually located on ceilings, so people generally don’t get close enough for there to be any danger.
Much of commercial kitty litter is made from a clay called bentonite that contains natural uranium and thorium. The uranium emits alpha particles. This is not a problem for the cats and cat owners but can be a problem if disposed of in landfills where ground water could leach the uranium and thorium into supplies of drinking water.
Glossy paper used for things like printing photographs gets its shine from a white clay called “kaolin.” Kaolin contains traces of natural thorium and uranium. The uranium emits alpha particles. An individual piece of such paper is no health threat.
Please read Part 3