Explanation required for venting radon gas above home's roof.
In homes with forced air heating and cooling systems, the main risks associated with radon gas are lung cancer and long-term respiratory harm due to radon accumulation in indoor air. Radon, a radioactive gas, seeps from the soil through foundation cracks and can become concentrated indoors[1][5].
To mitigate radon risks in such homes, several effective methods can be employed:
- Sub-slab depressurization (SSD): This technique involves installing a fan and pipe system beneath the foundation to create suction that draws radon gas out before it enters the home. Active SSD uses an electric fan for consistent removal and vents radon safely above the roof[1][5].
- Sealing foundation cracks and openings: Sealing entry points such as cracks in walls, floors, gaps around pipes, or sump pits is an essential first step to reduce radon entry[1][3].
- Sump pit depressurization: For homes with sump pumps, sealing or depressurization systems specifically address radon entry through sump areas while maintaining water drainage[1].
- Crawl space encapsulation and ventilation: Sealing crawl spaces with plastic sheeting and ventilating them reduces radon accumulation for homes with crawl space foundations[1].
- Radon monitoring: Continuous radon monitors can be integrated with home systems to provide real-time detection and help verify that mitigation is effective[1].
When it comes to forced air systems, additional measures are necessary:
- Radon cannot be filtered by standard air filters (including HEPA filters) in HVAC systems, so relying on air filtration alone is ineffective for radon removal[4].
- Properly locating fresh air intakes away from radon entry points and sealing air leaks around HVAC ducts can help limit radon intake and spread.
- Preventing dry traps and sealing utility tunnels or crawlspace openings connected to the HVAC system reduces radon migration into the building through mechanical rooms or ducts[2].
It is worth noting that the Consumer's Guide to Radon Reduction and Building Radon Out, resources for reducing radon risk and building radon-resistant homes respectively, do not discuss the dramatic fall-off in radon concentration when discharged via a radon mitigation system above the roof, nor the chemical properties of radon gas, nor the distribution of radon gas in a house with forced air heating and cooling[2][3][4].
Moreover, these resources do not mention the EPA's disallowance of ground level discharge of radon primarily because of the potential for re-entrainment of the gas into the house, or the rapid decrease in radon concentration to background levels at 3-4 feet from the discharge point[2][3][4].
For a comprehensive understanding of radon and its effects on homes, it is advisable to consult reliable sources such as the EPA or reputable organisations specialising in radon mitigation.
[1] EPA. (n.d.). Radon in Homes. Retrieved from https://www.epa.gov/radon/radon-homes [2] Consumer's Guide to Radon Reduction. (n.d.). Retrieved from https://www.epa.gov/radon/consumers-guide-radon-reduction [3] Building Radon Out: A Step-by-Step Guide. (n.d.). Retrieved from https://www.epa.gov/radon/building-radon-out-step-step-guide [4] U.S. Department of Energy. (n.d.). Radon: Protecting Your Family from Radon Gas. Retrieved from https://energy.gov/energysaver/radon-protecting-your-family-radon-gas [5] Health Canada. (n.d.). Radon in Homes. Retrieved from https://www.canada.ca/en/health-canada/services/radiation-protection/radiation-exposure/radon/homes.html
