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External Background Radiation 60 mrem/yr, US Average
Natural K-40 and Other Radioactivity in Body 40 mrem/yr
Air Travel Round Trip (NY-LA) 5 mrem
Chest X-Ray Effective Dose 10 mrem per film
Radon in the Home 200 mrem/yr (variable)
Man-Made (medical x rays, etc.) 60 mrem/yr (average)
A conversion from counts per minute (cpm) to dose rate (rads/hr, mrads/hr, etc.) is possible, but the conversion factor depends on the kind of detector being used and on the type of radiation being measured and frequently on the energy of the radiation. The relationship between count rate and dose rate is usually established through empirical calibration procedures in which the detector is exposed in a radiation field of the radiation type and energy of interest at a known dose rate, and the count rate is recorded. If the instrument being used has an adjustable discriminator the observed count rate will also be affected by the setting of the discriminator. Changes to the operating voltage and other operating parameters may also affect the observed count rate.
Originally posted by burntheships
Ok guys and gals...hear me out. I think the answer here is that the
Denver International is taking in flights from Japans evacuations.
When reporting radiation readings, units of measurement matter. The EPA readings are apparently in CPM (Counts per Minute), but CPM levels are not standardized, and instead depend upon the design of each model of detection instrument. So readings in CPM are not comparable except to historical readings made by the same instrument. I am hoping that the EPA detectors are something much more specialized and sensitive than the models typically used by our Monitoring Stations. For example, if a "counting tube" has a larger physical size and greater surface area, then it follows that the count rate, measured by the number of radiation particles that it "captures", will thus be higher.
In trying to understand what these readings mean, here is some information which I found.
With all that is going on, it feels important for me to understand what I am looking at. In a true emergency situation, I don't want to be waiting for someone to tell me if I am going to be getting a deadly dose of radiation in 5 minutes. It could be too late by then.
Originally posted by Northwarden
Then again, maybe all that's being said is that there's better nights to venture outside? I don't think anyone's talking about deadly doses of radiation, and I suspect higher radiation levels are a commonly known fact for those living in Denver. Many will also just be getting used to regular checking of these facts. There was nothing wrong with this amount of concern, levels are too high.edit on 30-3-2011 by Northwarden because: (no reason given)
Originally posted by YourPopRock
This is bad. Very very bad!
Originally posted by YourPopRock
reply to post by ColoradoJens
It means hide!
Originally posted by idunno12
I agree that according to the posted website, anything over 100 cpm triggers an "alert". But what does that alert truly mean? And what is causing the levels to swing back and forth as much as 30 cpm in either direction tonight?