In the air, radon decays to radon progeny that are solids, and are present in the building air as fine particles. Because radon is a gas, a fraction of the radon produced in the soil can find its way into a building. The presence of uranium in soil and rock is an important indicator of places where radium and radon can be present.
Less important sources of radium are in ground water and building materials. Radium in the soil directly under a building is normally the major source of indoor radon. The document Quantities and Units of Ionizing Radiation provides more details on the units of ionizing radiation. For making comparisons between the data from different sources, the following conversion chart may be useful: Measurement data are reported in either of the above units. Occupational exposure to radon progeny is expressed in working level months (WLM) and a working level month is equivalent to the exposure at an average concentration of 1 WL for 170 working hours.
AIR DOC RADON FULL
This situation is called full equilibrium and is extremely unlikely to occur. In the extreme case 1 WL corresponds to 100 pCi/L of radon. However, the relative concentration of radon and radon progeny may vary from one building to another. One WL of radon progeny corresponds to approximately 200 pCi/L of radon in a typical indoor environment. The concentration of radon progeny is measured in units of working level (WL) which is a measure of the potential alpha particles energy per litre of air. One Bq corresponds to one disintegration per second. The concentration of radon in the air is measured in units of picocuries per litre (pCi/L) or becquerels per cubic meter (Bq/m 3).