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Radiation Facts For Common Sense Safety
If you are on this page of our website you obviously have made a decision to learn more about radiation and more specifically how to protect yourself and loved ones from the inherent dangers associated with exposure to harmful radiation.

How do we become exposed to harmful radiation? Actually we are all continuously exposed to “background” radiation from the Earth’s crust, cosmic microwaves, and various man made sources most of which are considered normal and happen to be harmless as the human body is able to repair damaged cells faster than these sources of radiation can damage them. Sources of more harmful radiation are of course nuclear detonations and nuclear power generation facility accidents like Fukushima, Chernobyl, and Three Mile Island.

Considering the many exceptions that exist with regards to exposure we will discuss in general; accident oriented types of events and nuclear detonations and offer some instruction that can make a big difference in living and staying healthy versus suffering unrecoverable effects and or dying from over exposure. Due to the vast amount of information on the topic and in an effort to not duplicate the information already available on the internet we have provided valuable links to other websites below for your reference and review.

Given the eventual likely hood that events like Fukushima can happen all of us would be wise to invest in personal detection equipment so as to have a detection device(s) on hand in a survival or emergency kit before a disaster happens. Considering the potential for exposure to a lethal radiation dose it may be appropriate to even have two detection devices; one for measuring lower levels and another for mid to high level detection. Finding one device that can do both may be cost prohibitive for some.

If there is a significant radiation threat and you only have low level detection capability you would not be able to determine for yourself if there is in fact a hazardous or even fatal dose rate threat (500 Roentgens/hour for example) as you would only be able to detect up to a certain level with typical low level detection capabilities being around 100 milliroentgens/hour (100 mR/hr). In a 24 hour period this would be equivalent to 2400 mR/day or 2.4 Roentgens/day (R/day) which just so happens to be 1400 to 2400 times the average exposure limit for a human being in one year. With this in mind it is perceivable an individual could assume that there is not a significant threat and then in ignorance choose to “roll the dice” so to speak and suffer the dire consequences of a lethal exposure.

The average dose rate for a person in the United States is only about 1 mR/day or approximately 360 mR/yr with some estimates as much as 620 mR/yr (.36 R/yr to .62 R/yr or .04 mR/hr to .07 mR/hr) taking into consideration profession and medical imaging procedures like X-rays and CT Scans.

Limits for Exposure

   Occupational Dose limit;
   (United States - Nuclear Regulatory Commission/ US - NRC)
   Occupational Exposure Limits for Minors
   Occupational Exposure Limits for Fetus
   Public dose limits due to licensed activities (NRC)
   Occupational Limits (eye)
   Occupational Limits (skin)
   Occupational Limits (extremities)
Exposure - 1000 milliroentgens (mR) = 1 roentgen (R)

   5,000 mR/year     5,000 mR = 5 R
   500 mR/year        500 mR = 0.5 R
   500 mR                 -------------------
   100 mR/year        100 mR = 0.1 R
   15,000 mR/year   15,000 mR = 15 R
   50,000 mR/year   50,000 mR = 50 R
   50,000 mR/year   -------------------


With a basic understanding of non-hazardous radiation levels, what levels of exposure do we need to be concerned about? Well this too can vary some what from individual to individual due to the amount of time of exposure, the type of radiation, as well as the type of exposure. To stay on the safe side an average adult should stay away from environments with dose rates > 5 mR/hr. This dose rate translates to almost 44 Roentgens in a year or 70 to 121 times the average exposure limit.

While limiting exposure to threats > 5 mR/hr is highly recommended, it is widely accepted that an average adult likely would not show symptoms or sickness from exposure until a dose of at least 50 to 100 Roentgens/R or 50,000 to 100,000 milliroentgens/mR is accumulated over a 6 to 12 hour period. Review the chart below to familiarize yourself with dose rates, exposure, and their respective symtoms.

Below is a table summarizing the expected health effects for an adult assuming the cumulative total radiation exposure was all received within a weeks time.  For children, the effects can be expected at half these dose levels.

Total Exposure:          Onset and Duration of Initial Symptoms and Disposition

30 to 70 R (Roentgens)    

70 to 150 R    

150 to 300 R    

300 to 530 R    

530 to 830 R    

830 R and above    

From 6-12 hours: no symptoms to slight incidence of transient headache and nausea; vomiting in up to 5 percent of personnel in upper part of dose range.  Mild lymphocyte depression within 24 hours.  Full recovery expected. (Fetus damage possible from 50R and above.)

From 2-20 hours: transient mild nausea and vomiting in 5 to 30 percent of personnel.  Potential for delayed traumatic and surgical wound healing, minimal clinical effect.  Moderate drop in lymphocycte, platelet, and granulocyte counts. Increased susceptibility to opportunistic pathogens.  Full recovery expected.

From 2 hours to three days: transient to moderate nausea and vomiting in 20 to 70 percent; mild to moderate fatigability and weakness in 25 to 60 percent of personnel.

At 3 to 5 weeks: medical care required for 10 to 50%.  At high end of range, death may occur to maximum 10%.  Anticipated medical problems include infection, bleeding, and fever.  Wounding or burns will geometrically increase morbidity and mortality.

From 2 hours to three days: transient to moderate nausea and vomiting in 50 to 90 percent; mild to moderate fatigability in 50 to 90 percent of personnel. 

At 2 to 5 weeks: medical care required for 10 to 80%. At low end of range, less than 10% deaths; at high end, death may occur for more than 50%.  Anticipated medical problems include frequent diarrheal stools, anorexia, increased fluid loss, ulceration. Increased infection susceptibility during immunocompromised time-frame.  Moderate to severe loss of lymphocytes.  Hair loss after 14 days.

From 2 hours to two days: moderate to severe nausea and vomiting in 80 to 100 percent of personnel;

From 2 hours to six weeks: moderate to severe fatigability and weakness in 90 to 100 percent of personnel.

At 10 days to 5 weeks: medical care required for 50 to 100%. At low end of range, death may occur for more than 50% at six weeks. At high end, death may occur for 99% of personnel.  Anticipated medical problems include developing pathogenic and opportunistic infections, bleeding, fever, loss of appetite, GI ulcerations, bloody diarrhea, severe fluid and electrolyte shifts, capillary leak, hypotension. Combined with any significant physical trauma, survival rates will approach zero.

From 30 minutes to 2 days:
severe nausea, vomiting, fatigability, weakness, dizziness, and disorientation; moderate to severe fluid imbalance and headache.  Bone marrow total depletion within days. CNS symptoms are predominant at higher radiation levels.  Few, if any, survivors even with aggressive and immediate medical attention.

One of the most notable differences between a nuclear detonation and an event like Fukushima in terms of radiation and exposure is that a nuclear detonation has a spike of extremely high levels of radiation output immediately following the explosion with a dramatic decay in the dose rate in the first 24 to 48 hours while Fukushima has not and likely will not see dose rates remotely close to a nuclear explosion but has and is consistently emitting a low to low/mid level of radiation over a long period of time. 



Hopefully reading this page has helped make it evident the ability to identify lower levels of radiation contamination in air, food, and water as well as higher and potentially lethal doses like a 500 R+ environment is essential.  We recommend adding personal detection devices to your survival and or emergency kits sooner than later to be best prepared for a future that is certainly uncertain.  When disaster strikes it's usually too late to take precautions.  Preparedness is wisdom in action, don't be caught unprepared particularly when your life is on the line.

For more information regarding; radiation, nuclear explosions and fallout, exposure, and preparedness you might want to visit the websites linked below.  Additionally we have included a link to a PDF document hosted here on our site for your consideration published by the United States Department of Homeland Security; “Planning Guidance for Response to a Nuclear Detonation”.

Remember when it comes to life safety preparation is fundamental.  Moreover, knowledge builds confidence and peace of mind that can keep you from panicing in a survival situation.  Thank you for visiting the Personal Radiation Detection website!  Share us with your friends and family and we look forward to hearing from you! 

  Planning Guidance for Response to a Nuclear Detonation

External Links:


   Rad Meters 4 U

   Idaho State University


   Environmental Protection Agency - EPA

   Occupational Safety & Health Administration - OSHA

   Fallout Radiation

   Radiation Network

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