Types of Radiation and your Radiation exposure limit
What is Radiation exactly? A simple definition of Radiation is energy sent out in the form of waves or particles. It is invisible, silent, and odorless. You are being exposed to radiation as you read this: from the earth, the sky, the sun, and the world around us. We refer to it as background radiation. Radiation is given off by a wide variety of processes, such as thermal activity, nuclear reactions, and by radioactive decay.
The 3 most common types of radiation are Alpha, Beta, and Gamma radiation.
· Gamma radiation is essentially photons, except with much higher energy, that can travel hundreds of miles through the air. Gamma radiation and x-rays are basically the same thing (a high energy wave), the difference being in how they are produced. A massive amount of gamma radiation is released during a nuclear blast or a nuclear plant meltdown. Gamma is considered the most dangerous form of radiation due to its ability to travel long distances and penetrate through the body.
· Beta radiation is made up of fast moving electrons. Beta, unlike gamma, is a particle and is capable of penetrating through several feet of air. They are most dangerous when combined with fallout dust and is taken into the body through the lungs or with contaminated food or water.
· Alpha radiation is made up of fast moving helium atoms. They contain very high energy, but due to their large mass they can be stopped by simply a few inches of air or a sheet of paper. The concern with Alpha, like Beta, is when it is absorbed into the body by getting inhaled or ingested. The number of lung cancer cases from inhaled alpha particles among uranium miners is much higher than the general population.
How can these levels of radiation be quantified? There are many different radiation units that are used, so it can get confusing. The following units of radiation are what you will most likely run across: Roentgen (R), RAD, REM, Sieverts (sV), and Gray (Gy). How are all these related?
· Roentgen(R) is a unit of exposure used to measure the strength of a radiation field at some point in air. The main advantage of this unit is that it is easy to measure directly with a high range survey meter or Geiger counter, but it is limited because it is only for deposition in air, and only for gamma and x rays.
· RAD stands for “Radiation Absorbed Dose” and represents the amount of radiation actually absorbed by some material. Different materials that receive the same exposure may not always absorb the same amount of energy. Therefore a RAD is used to refer to the total concentration of radiation that was absorbed in that material or body. For simplification: 1 Roentgen of Gamma Radiation exposure will result in approximately 1 RAD of absorbed dose. 1 RAD is the equivalent of 0.01 Gray (Gy), the standard SI unit.
· REM stands for “Roentgen Equivalent Man”. Some forms of radiation are more efficient at transferring energy from one object to the next. Therefore the REM unit levels the field by giving certain types of radiation multiplication factor (X). REM = RAD * X. For gamma and beta radiation, X = 1. For alpha radiation, the X factor can be as high as 20. 1 REM is the equivalent of 0.01 Sieverts (sV). 1 RAD of Gamma or Beta Radiation exposure will equal 1 REM of dose. Therefore, it can be said that 1 Roentgen = 1 RAD = 1 REM. Devices like the Nukalert will measure radiation doses of 0.1 R/Hr, all the way up to 50+ R/Hr, which is an optimal range when finding your way out of a radiation zone.
What exactly are your radiation exposure limits? The average American receives approximately 0.5 REMs (or 0.005 sV) of radiation per year from a wide variety of sources: cosmic, rocks, medical procedures (xrays, etc), Radon, internal sources, and consumer products. The maximum annual dose permitted by US radiation workers is 5 REM (.05 sV). The lowest dose that has been associated with a detectable increase in cancer rates is 10 REM (.1 sV) when absorbed over a short period of time. For reference, the Chernobyl incident recorded doses of at least 43 REM for some of the closest to the radiation plume. 100 REMs when absorbed in a short period of time, is enough to cause radiation sickness in an adult. 450 REMs is the lethal dose for a human being. In the case of a large 2-3 Megaton nuclear blast, those within a few miles of ground zero who survive but do not take shelter immediately will be exposed to up to 5000 REM per hour immediately after the explosion. The extremely high initial release of radiation from a nuclear weapon shows the importance of evacuating immediately out of the potential fallout zone. How will you know how much radiation you’ve been exposed to when you do find medical help? The RADsticker personal dosimeter will record a dose rate of up to 500 RADs. It could prove to be extremely useful to medical personnel to know how much dose you’ve received when treating you for various injuries from your exposure.
Don’t get caught in radiation fallout or near a radiation leak with no information and nowhere to go, get your Nukalert or RADsticker(s) today.
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