b'ACHIEVING SAFE RADON LEVELSACHIEVING SAFE RADON LEVELSIN ENERGY-EFFICIENT BUILDINGSBy Shahrzad Pedram (Entuitive), Adam Jarolim (JRS Engineering) and Rodrigo Mora (BCIT)The following is a short excerpt of a research article that will be published in BC Housings Technical Library. 1. INTRODUCTIONslabs, service penetrations in thenegative pressurization across theRadon is an invisible, odourless gassoil gas barrier, sump pits andbuilding enclosure, like exhaust-found in varying concentrations inslab-to-wall joints. only ventilation or naturally the earth and naturally released inaspirated oil and gas furnaces.2. A driving force from the the atmosphere. It can accumulate to dangerously high levels and become aground: In cold climates, a major3.force for radon entry into build- Insufficient indoor air dilution: health hazard when entrapped in build- ings is the stack effect that createsWithout sufficient ventilation, ings. Radon is the second-highest cause4 pollutants can accumulate in the of lung cancer, after smoking, in manynegative pressure differentialsindoor air.countries worldwide and is estimated topulling radon from the ground. account for about 3,300 deaths per yearOpenings in the above-gradeThe effect of the combination ofin Canada.building enclosure drive stackthese factors is dependent on the defi-effect and cause unintended and Potential entry routes for radon in homes with poured concrete uncontrolled ingress of radonciencies in the design, construction and In Canada, the building design team isfoundations include cracks, areas with exposed soil or rocks, responsible for developing mitigationthrough cracks or openings. Themaintenance of the building enclosure, openings for utility fixtures or hollow objects such as supportstrategies for buildings, which spanssame effect is created by heatingand the mechanical heating andposts (see figure 1). CAN/CGSB-149.12-2017various disciplines including archi- and ventilation systems that causeventilation systems.tecture, mechanical, geotechnical and enclosure engineering. The broad scopeExposed soil or rockCracks or flaws in Around utility penetrationsoften results in overlooked aspects ofin crawl spaces foundation walls and support postmitigation design.Hollow objects This article aims to raise awarenesssuch as supportabout how deficient buildings can riskpostshuman health in unintended ways and outlines existing Canadian codes and guidelines with reference to radon control in buildings.2. RADON ENTRY AND ACCUMULATIONIN BUILDINGSIndoor radon accumulation and human exposure in buildings occurs due to the dynamic interaction of three factors: Cracks or flaws in floor slab 1. A path for entry at the founda-tion: Radon enters a building through the airflow and diffu-sion mechanisms. The dominant mechanism is pressure-driven airflow. The most common loca-tions for radon entry are cracksFloor/wall joints Floor drains & sumpsin the foundation walls and floor FIGURE 1. POTENTIAL ENTRY POINTS OF RADON IN FOUNDATION NOTE 1The only way to know if a home has a high radon concentration is to measure the radon Figure 1 WALLS AND POURED CONCRETE FLOORS (CAN/CGSB-149.12-2017).20 BCBEC ELEMENTSA BCBEC PUBLICATION concentration.Typical radon entry routes in poured concrete foundation walls and floors.NOTE 2Figure has been taken from Health Canada, Radon Reduction Guide for Canadians, May 2014.Figure 1Potential entry points of radon in foundation walls and poured concrete floorsIn 2007 the Government of Canada in conjunction with the Federal Provincial Territorial Radiation Protection Committee updated its guideline for exposure to radon in indoor air after a broad public consultation process which was based on new scientific information on health risk from indoor radon exposure.The current Government of Canada Guideline for radon in indoor air is: Remedial measures should be undertaken in a dwelling whenever the average annual radon concentration exceeds 200 becquerels per cubic metre (Bq/m) in the normal occupancy area. The higher the radon concentration, the sooner remedial measures should be undertaken. When remedial action is taken, the radon level should be reduced to a value as low as practicable. The construction of new dwellings should employ techniques that will minimize radon entry and will facilitate post-construction radon removal should this subsequently prove necessary.For more information about radon and the Guideline, visit the Health Canada website https://www.canada.ca/en/health-canada/services/environmental-workplace-health/radiation/radon.html#wb-info or call 1-800-O-Canada. CGSB 2017All rights reserved iii'