#### How much radiation exposure is too much?

The following data is from an industry source believed to be reliable. However, you should verify the following government data - research the NIH (**National Institute of Health**). Additionally, "acceptable" levels of radiation exposure are somewhat subjective, so we encourage you to make your own conclusions as to the maximum levels of radiation exposure which would be acceptable to you: The US Government recommends that you limit your dosage or exposure of radioactivity to the following:

Occupational 5R/yr = 5,000mR/yr |

Non-Occupational .1R/yr = 100mR/yr |

+ 100mR/yr (background)*

= 200mR/yr total

*Estimated annual exposure to background radiation

#### How to calculate your annual radioactive dosage or exposure:

First measure your dose rate using a Geiger counter that reads out in mR/hr. | |

Understand that that dose rate includes both the radiation from the particular source of your focus that is emitting radioactivity, along with ever present background radiation. | |

Then figure out the number of hours in a year that you are exposed to that dose rate. | |

Then multiply the dose rate, expressed in mR/hr, by the number of hours of your exposure over the course of a year. | |

Finally, compare your annual exposure to the NIH standard above. |

** Examples:**

## Handling Radioactive Ore: |

1.) Assume the dose rate from a high grade, 1" radioactive sample of Uraninite equals 100 mR/hr.

2.) Assume exposure time of just 2 hours for the entire year.

3.) Therefore, annual dosage from the radioactive ore equals 200 mR (100 mR/hr x 2 hours per year).

## Airplane Flights: |

1.) Assume a commercial airline pilot flies at a ceiling of 40,000', and at that altitude, where cosmic rays are more intense, receives a dose rate of .3 mR/hr.

2.) Assume 20 hours of flight time per week, or 1,040 hours per year.

3.) Therefore, annual dosage from high altitude flights equals 312 mR (.3 mR/hr x 1,040 hours per year).

## Granite Countertops: |

1.) Assume the dose rate from a granite countertop in a kitchen is .05 mR/hr.

2.) Assume close proximity to the countertop of 3 hours per day, or 1,095 hours per year.

3.) Therefore, annual dosage from the granite equals 55 mR (.05 mR/hr x 1,095 hours per year).

## High Altitude Living: |

1.) Assume a Sherpa living in Tibet at 12,000', which high altitude means less atmospheric and electromagnetic shielding of cosmic rays, receives a constant dose rate of .04 mR/hr.

2.) Given that 365 days a year x 24 hours per day equals 8,760 hours per year of exposure.

3.) Therefore, annual dosage from high altitude living equals 350 mR (.04 mR/hr x 8,760 hours).

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