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Guide for Radon Measurements in Public Buildings

1. Introduction

1.1 Scope and Summary

This document is intended for persons and organizations intending to carry out radon measurements in public buildings. These buildings, considered dwellings, have a high occupancy rate and/or residency period for members of the public. The types of buildings include hospitals, schools, long-term care residences and correctional facilities.

The purpose of the testing is to evaluate radon levels in order to determine the need for remedial action to protect the dwelling residents.

Occupational exposure of workers to radon is addressed separately through existing guidelines or regulations such as the Canadian Guidelines for Management of Naturally Occurring Radioactive Materials (NORM) and the Canada Labour Code.

The scope of this document is limited to guidance regarding types of measurement devices, device placement, measurement duration, and the interpretation of measurement results regarding corrective action for health protection in public buildings and schools.

1.2 What is Radon?

Radon is a radioactive gas that is formed naturally by the breakdown of uranium in soil, rock and water. It cannot be detected by the senses, i.e., it is colourless and odourless; however, it can be detected with scientific instruments. Radon usually escapes from the ground into outdoor air where it mixes with fresh air resulting in concentrations too low to be of concern. However, when radon enters an enclosed space, such as a building, it can accumulate to high concentrations. The only known health risk associated with exposure to radon is an increased risk of developing lung cancer. The level of risk depends on the concentration of radon and length of exposure.

Because the source of most radon in public buildings is the soil on which it is standing and radon, which escapes from the soil and infiltrates a building, tends to be heavier than air, higher indoor radon levels are more likely to exist at the lower levels of the building. In some cases, higher radon concentrations have been found at upper levels, due to radon movement through elevators or other air shafts in buildings. Health Canada recommends testing every fifth floor in multi-level buildings.

1.3 Radon Guideline

Although there is no regulation that governs an acceptable level of radon in Canadian homes or public buildings (considered as "dwellings"), Health Canada, in partnership with the provinces and territories, has developed a guideline. This guideline provides Canadians with guidance on when remedial action should be taken to reduce radon levels. The following guideline was approved by the Federal Provincial Territorial Radiation Protection Committee in October 2006 and adopted by the Government of Canada on June 9, 2007:

(See page 10 on units and page 18 on time frame for remediation.)