Radon levels are generally highest in cellars and basements because these areas are nearest to the source and are usually poorly ventilated. If this upper limit is exceeded, remedial action should be taken to reduce the radon levels. However, because there is some level of risk at any level, Health Canada suggests that homeowners may want to reduce levels of radon to as low as possible. In Canada the provincial governments have jurisdiction over the health effects of background radiation. Canadians concerned about possible radon daughter exposure should contact their local provincial government office for further details.
Little information exists on radon levels in Canadian buildings.
One collection of Canadian indoor radon measurements, published in 1980, was the result of a cross-country study of radon in private homes. The following table, which summarizes the results, shows that levels varied from one geographic area to another and even from house to house. In general, the study showed higher levels of radon where ventilation rates were low. A study carried out in the United Kingdom showed varying degrees of elevated radon levels in offices and similar workplaces in areas where radon levels were high in homes. Indoor radon level is measured by air sampling and by alpha dosimetry using radon track etch dosimeters.