Dwellings: Indication of high annual radon daughter concentration (NT BUILD 231)

  • Report #: NT BUILD 231
  • Approved: March 1982
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This NORDTEST method refers to a integrated measurement of the radon daughter concentration in dwellings using a track etch detector, sensitive to alpha radiation. The method can also be applied in other building types where people stay for a long time. e.g. nursing homes. The measurement is performed for a time sufficiently long to smooth out short-time variations, although longtime variations nave to be taken into account. The obtained exposure is used for estimating the annual average of the radon daughter concentration. When making an estimation, factors having an influence like indoor climatic conditions during the test have to be taken into consideration. The main purpose of the test is to separate dwellings with excessive radon daughter concentrations (> 400 Bq/m3) from the remainder. If lower concentrations are to be established the accuracy is lower. The accuracy of the test is determined by type of film and area of analysis.

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