Signs, formation, and measurement

Radon is a naturally occurring radioactive gas. It has no taste, smell, or colour, and therefore requires special equipment in order to detect its presence.

Although radon can be found in all soils and rocks to some extent, the amount varies throughout the country and throughout the year.

Radon forms in the ground due to the radioactive decay of small amounts of radium. Radium results from the radioactive decay of uranium. The gas released from the decay of radium rises to the surface of the ground, and generally the gas reaches the atmosphere and becomes diluted.

Problems arise, however, where radon gathers in enclosed spaces and the concentration rises to unacceptable levels in areas where the concentration of radon in the underlying geology is high, and depending on the construction details of the building.

The unit of measurement for radon is Becquerels per cubic metre (Bq/m^3^): 1 unit equates to radon at a concentration that emits 1 particle of radiation per second per cubic metre.

200 Bq/m^3^ is the National Reference Level (NRL) for radon in houses. RPII recommend remedial work to lower the value to below 200 Bq/m^3^ where the value is greater than the NRL.