The Suitability of Geiger Counters for Detecting Radon

The question whether Geiger counters are actually suitable for detecting radon is debatable. The Radalert 50, Radalert 100, Inspector Alert and Inspector do not measure radon gas specifically, however experiments using the Radalert in a controlled environment with different radon gas levels showed that the average counts per minute rose and fell with radon concentrations.

The detected radiation combines emissions from radon and its daughters. The experiment results showed a linear increase of counts per minute with regards to increased radon concentration from 17 CPM at 0 radon concentration to 33 CPM at a concentration of 65 pCi/l. At 4-5 pCi/l, the increase was 1 CPM. The Inspector has not been tested with radon, however should be more effective, as it has an increased sensitivity to alpha and beta radiation. The use of the Radalert 50, Radalert 100, Inspector, or the Inspector Alert as an alternative to EPA-approved carbon canisters or other standard methods of testing for radon is not recommended.

Use of Radalert 100 or the Inspector Alert for Experimental, Educational, or Screening Purposes

The following guidelines may be helpful if one wants to use the Inspector Alert or the Radalert 100 for experimental, educational, or screening purposes in regards to radon, the following guidelines may be helpful.

  • Radon may enter mostly in homes or other buildings through cracks or openings in the floor around pipes or conduit, unsealed wall-floor joints, and underground hollow block walls. Dirt floors in basements are especially vulnerable. Unventilated basements or closets normally have increased levels of radon than well-ventilated areas.
  • Before radon screening, baseline measurements need to be established; for example, determine the background level in a location outdoors three feet above the ground and in a location in a place in the house not likely to have radon accumulation. It is best to accumulate the baseline counts for 12 h as described below.
  • For radon screening, the instrument is placed on the floor near any suspected entrance point.
  • For best results, air exchanges between indoors and outdoors must be kept at a minimum for 12 hours before and during the test.
  • Set the display to Total and accumulate the counts for 12 hours in each location.
  • Divide the total count for the period by the exact number of minutes to get the average CPM.
  • In case the 12-hour average CPM in the home is more than 1 CPM higher than outdoors, further testing for radon can be done using carbon canisters or other EPA-approved methods.
  • Another way of radon screening is by checking the air particulates, or dust.
  • Several radon daughters, which account for much of the radiation produced by radon, are negatively charged and attach themselves to the dust.
  • Accumulated dust by wiping a television or computer monitor screen with a piece of tissue paper (the CRTs are positively charged and this specifically attracts the negatively-charged particles) or by attaching filter paper or medical gauze to a vacuum cleaner nozzle and running it for half an hour.
  • Dust can also be measured on an air-conditioning, heating system, or air-purifying filter.
  • A high measurement from concentrated air particulates is an indication of the presence of radon.
  • Since the radon daughters are concentrated, high readings are not unusual if any radon gas is present.

This information has been sourced, reviewed and adapted from materials provided by International Medcom.

For more information on this source, please visit International Medcom.


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