Tornado Alley (PROG)

[fuagf]

"The surface of the pile, which looked like soil, had gamma ray readings of about 85 microsieverts per
hour. The total reading, including beta rays, came to 1 millisievert per hour." .. that's from your 2nd one ..

Mystery objects with high radiation found on Fukushima coast
August 03, 2013
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201308030015 [with comments]

i wondered what a 'normal' reading was .. the last bit ..

Normal Radiation Exposure

The higher up you live, the more radiation you are exposed to every day. This is because cosmic rays from the sun are more common higher in the atmosphere. By the time they reach the Earth's ground, some of them will have been absorbed - explaining the lower level of radiation closer to the ground. Additionally, the intensity of cosmic radiation also obeys the inverse square law .. ) . The ground of the Earth is also further away from the sun than higher up in the atmosphere. However, note that living in a canyon below sea level does not necessarily mean you are exposed to less radiation. In fact, you may be exposed to more because of the canyon's walls containing minerals that may be naturally radioactive.

At sea-level, the average radiation level is approximately 0.03 microsieverts per hour. As the altitude increases, the radiation exposure increases exponentially. Mexico City, 2240 m above sea-level, is exposed to about 0.09 microsieverts per hour; La Paz (in Boliva, South America) - the highest city in the world - has radiation of about 0.23 microsieverts per hour.

[ Note: a micro is 1/1000 of a milli .. http://physics.nist.gov/cuu/Units/prefixes.html ]

Click [ link kapoot: sub. http://en.wikipedia.org/wiki/La_Paz here for a map of where La Paz is located. (Map courtesy of Lonely Planet.)

Radon is a radioactive gas formed from the decay of metals like uranium and thorium. It is in the air that we breathe, but only in very small proportions - in trace amounts of less than 0.01%. Nevertheless, prolonged and concentrated exposure to radon gas is believed to cause lung cancer.

Frequent international aircraft travellers will be exposed to more radiation because they will spend more of their time up in the atmosphere, closer to the cosmic rays.

http://library.thinkquest.org/C004606/applications/measuringrad.shtml

.. so that pile at "85 microsieverts per hour" is (85/.23) 369.6 times higher than the radiation level in La Paz .. wonder what the air reading is about there? .. now how does micro relate to milli? .. ok .. "10-3 milli" m and "10-6 micro µ" .. http://physics.nist.gov/cuu/Units/prefixes.html .. milli = 1/1000 and micro = 1/1000000 .. so a micro is 1/1000 of a milli .. i.e a milli m is 1000 times bigger than a micro µ .. ok ..

General questions and comments on radiation risk

In large doses, radiation can cause serious tissue damage and increase a person’s risk of later developing cancer. The low doses of radiation used for imaging tests might increase a person’s cancer risk slightly, but it’s important to put this risk into perspective. In this section we will answer some of the more common questions people have about radiation risks linked to imaging tests.

How much radiation is the average person exposed to during day-to-day life?

We are constantly exposed to radiation from a number of sources, including radioactive materials in our environment, radon gas in our homes, and cosmic rays from outer space. This is called background radiation and it varies across the country.

The average American is exposed to about 3 mSv (millisieverts) of radiation from natural sources over the course of a year. (A millisievert is a measure of radiation exposure.) Much of this exposure is from radon, a natural gas with levels that vary from one part of the country to another.

For example, because the earth’s atmosphere blocks some cosmic rays, living at a higher altitude increases a person’s exposure – residents in the plateaus of New Mexico and Colorado, have an annual exposure level of about 1.5 mSv more per year than people living at sea level. And a 10-hour airline flight increases cosmic ray exposure by about 0.03 mSv.

Smoking a pack of cigarettes a day exposes the smoker to an extra 53 mSv per year.

How much does an imaging test expose a person to radiation?

Actually, not much, but it depends on the imaging test used. A single chest x-ray exposes the patient to about 0.1 mSv, which is about the radiation dose people are exposed to naturally over the course of about 10 days. A mammogram exposes a woman to 0.4 mSv, or about the amount of exposure a person would expect to get in about 7 weeks.

Some other imaging tests have higher exposures. A lower GI series using standard x-rays exposes a person to about 8 mSv. A CT scan of the abdomen (belly) and pelvis exposes a person to about 10 mSv, this goes up to 20 mSv if the test is done with and without contrast. A CT colonography exposes you to about 10 mSv of radiation. Keep in mind that these are estimates, and studies have found that the amount of radiation you get can vary a great deal.

If you have concerns about the radiation you may get from a CT scan, or any other imaging test, check with the facility that will perform the test. (Remember that MRI and ultrasound exams do not expose you to radiation.) You may also want to keep a “medical imaging history” that will allow you to track your own medical imaging history and share it with your health care providers. (One can be found online at www.radiologyinfo.org. See the “To learn more” section.) The best advice at this time is to only get imaging tests that are needed and try to limit your exposure to all forms of radiation.

How much does the extra radiation increase a person’s cancer risk?

Researchers have estimated that radiation exposure from the average diagnostic x-ray may increase cancer risk very slightly (likely on the order of hundredths to thousandths of one percent). Of course, this can be affected by the type of test done, the area of the body exposed, and other factors.

Radiation experts say that the risk levels represented in imaging tests are only very small additions to the 1 in 5 chance we all have of dying from cancer. It’s hard to know if and if so, just how much the radiation exposure from imaging tests increases a person’s cancer risk. Most studies on radiation and cancer risk have looked at people exposed to very high doses of radiation, such as uranium miners and atomic bomb survivors. The risk from low-level radiation exposure is not easy to calculate from these studies.

We do know that children are more sensitive to radiation and should be protected from it as much as possible.

Because radiation exposure from all sources can add up over a lifetime, and radiation can, indeed, increase cancer risk, imaging tests that use radiation should only be done for a good reason. In many cases, other imaging tests such as ultrasound or MRI may be used. But if there’s a reason to believe that an x-ray or CT scan is the best way to look for cancer or other diseases, the person will most likely be helped more than the small dose of radiation can hurt.

Last Medical Review: 01/11/2013 - Last Revised: 01/11/2013
http://www.cancer.org/treatment/understandingyourdiagnosis/examsandtestdescriptions/imagingradiologytests/imaging-radiology-tests-rad-risk

.. i'm glad the reading of the pile is in microsieverts ..