page_title: Environmental radioactivity
section_title: Short lived
hierarchical_section_title: Environmental radioactivity / Man-made / Fission products / Short lived
caption_attribution_description: English: The external relative gamma dose for a person in the open near the Chernobyl disaster site.
context_page_description: Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 and technetium-99, are only found on Earth as a result of human activity, and some, like potassium-40, are only present due to natural processes, a few isotopes, e.g. tritium, result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238, can be affected by human activity.
context_section_description: An example of a short-lived fission product is iodine-131, this can also be formed as an activation product by the neutron activation of tellurium.
  In both bomb fallout and a release from a power reactor accident, the short-lived isotopes cause the dose rate on day one to be much higher than that which will be experienced at the same site many days later.  This holds true even if no attempts at decontamination are made.  In the graphs below, the total gamma dose rate and the share of the dose due to each main isotope released by the Chernobyl accident are shown.
caption: The external gamma dose for a person in the open near the Chernobyl site.
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