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    Radiation is energy in the form of waves and particles.
    It is a natural phenomenon that has existed since the beginning of time and is found everywhere.

    Exposure to radiation is measured in millirems. The average person receives approximately 360 millirem per year from all sources of natural and man-made radiation. We are exposed to naturally occurring background radiation everyday of our lives from such things as the earth, cosmic rays, radon gas, naturally radioactive foods such as bananas, buildings made of naturally radioactive materials such as granite, and even, each other, as our bodies are naturally radioactive. The greatest single source of background exposure (an average of 200 millirem per year) comes from radon gas. We are also exposed to man-made radiation from such things as dental x-rays, medical procedures, and televisions. Certain activities increase our exposure to radiation such as smoking (cigarette smoke contains radioactive particles) or airline travel (radiation exposure is higher at higher elevations).

     



    Schematic: RADIATION: RISKS AND REALITIES
    United States Environmental Protection Agency

     

    TYPICAL BACKGROUND RADIATION LEVELS

    Location Dose

    U.S. National Average 300 millirem/year

    Connecticut 284 millirem/year

    Colorado (Denver) 364 millirem/year

    France (near Radon Springs) 1,600 millirem/year

    India (parts of) 1, 140 millirem/year

    Brazil (parts of) 17,500 millirem/year

    Note: An individual's exposure to radiation dose is measured in "rem."

    Most radiation dose is so small that it is measured in millirem (1/1,000 or .001 rem).

     

    SOURCES OF RADIATION
    (1 rem = 1,000 millirem)
    Annual Radiation Dose (millirem/year)

    I. Natural Radiation Sources

    • A. Cosmic (from outer space)
      • Connecticut and Massachusetts 28

      • Colorado 125

    • B. Terrestrial (from the earth's surface)
      • Connecticut and Massachusetts 16

      • Colorado 63

    • C. Food Consumed and the Human Body Itself 40

    • D. Inhaled Indoor (Radon) 200

    SUBTOTAL OF A, B, C, D

    • Connecticut and Massachusetts 284
    • Colorado (Denver) 428

    II. Technologically Enhanced Exposures to Natural Sources

  • A. Radioactivity in Building Materials 7
      • (varies from wood frame to brick to stone)
  • B. Air Travel (round trip cross-country) 5

  • C. Natural Gas (Radon-222)
      • Cooking (lung) 5

      • Heating (lung) 22
  • D. Smoking (30 cigarettes/day)
    • Certain areas of the lung Up to 16,000

    III. Man-made Sources

  • A. Medical Diagnosis (per capita) 53
  • B. Consumer Products (TV) 1
  • C. Nuclear Power Station (within 50 miles) 0.1
    • (at site boundary) 1 to 3

    The average resident of Connecticut and Massachusetts receives a total of about 360 millirem/year from natural and other common sources of radiation.

    References: National Council on Radiation Protection and Measurements Report No. 92 (12/87), Report No. 93 (9/87), Report No. 94 (12/87, Report No. 95 (12/87).

    HEALTH EFFECTS OF RADIATION EXPOSURE

    Whole Body Radiation Dose Effectsl
    1,000,000 Millirem - Death occurs with 30 days of exposure in 100 percent of the cases.
    500,000 Millirem - Clinical recovery if exposure rate is not more than 10,000 - 50,000 millirem/day.
    450,000 Millirem - 50 percent die within 30 days of exposure (without medical care)
    200,000 Millirem - 1 percent die within 30 days (without medical care), 5 percent suffer nausea.
    25,000 Millirem - EPA Protective Action Guide for Emergency Workers, possible clinical effects.
    4,500 Millirem - NU's administrative guideline for maximum annual dose to workers.
    3,000 Millirem - NRC's calendar quarter exposure limit for workers.
    500 Millirem - NRC regulation level for an individual in the general public from all man-made sources (except medical)
    300 Millirem - Average annual natural background level in United States.
    25 Millirem - EPA's annual limit for dose to individuals in the public who live within two miles of a nuclear plant
    <1 Millirem - Average annual dose to individuals in the public who live within two miles of a nuclear plant
    (1) Unless otherwise noted, total dose occurs within a few hours to one day.
    (2) 1,000 mrem = 1 rem

    Activities Which Result in a Dose of 0.1 mrem

     

    Type of Exposure

    2.4 hours at the elevation of Denver.

    15 mintes at 30,000 feet of commercial subsonic jet travel.

    4.5 monthss at a location 20 feet higher in elevation.

    4.4 hours in a tightly insulated energy-efficient house.

    1 year @ 8 hours per night sleeping with another person.


    Source of Radiation

    Cosmic/terrestrial
    Cosmic rays
    Cosmic rays
    Radon gas
    Natural Potassium-40
    Radiation in the building materials