Radon Safety

What is Radon Safety?

A school district maintenance director ordered routine air quality testing in a group of elementary school buildings constructed in the 1970s after a neighboring district discovered elevated radon levels. The results came back showing radon concentrations of 14.8 picocuries per liter in three ground-floor classrooms -- nearly four times the EPA action level of 4 pCi/L. Hundreds of children and staff had occupied those rooms for years with no symptoms and no prior testing, accumulating lung cancer risk equivalent to smoking nearly a pack of cigarettes per day. The remediation required sub-slab depressurization systems in all affected buildings and triggered a district-wide testing mandate that found additional elevated readings in two more schools.

Radon safety involves the detection, measurement, and mitigation of radon gas -- a naturally occurring radioactive gas produced by the decay of uranium in soil and rock that seeps into buildings through foundation cracks and openings. As the second leading cause of lung cancer after smoking, radon requires systematic testing and proven engineering controls because it cannot be seen, smelled, or tasted, and its health effects develop over years of cumulative exposure.

Key Components

1. Understanding Radon Sources and Entry Paths

• Recognize that radon originates from the natural decay of uranium present in virtually all soils and can accumulate to dangerous levels in any building regardless of age, construction type, or geographic region
• Identify common entry points including cracks in concrete slabs, gaps around service pipes, construction joints, sump pump openings, and crawlspace soil exposure
• Understand that radon levels vary significantly from building to building -- even adjacent structures on the same street can have dramatically different concentrations based on subsurface geology and foundation conditions
• Recognize that well water drawn from underground sources can also carry dissolved radon that releases into indoor air during showering, laundering, and other water use

2. Testing Methods and Interpretation

• Conduct short-term tests (2-90 days) using charcoal canisters or alpha-track detectors as an initial screening, followed by long-term tests for a more accurate annual average measurement
• Place test devices in the lowest livable level of the building -- typically a basement or ground-floor room -- with doors and windows closed to reflect normal occupancy conditions
• Interpret results against the EPA action level of 4 pCi/L, understanding that no level of radon exposure is considered completely safe and that levels between 2-4 pCi/L still warrant consideration for mitigation
• Retest after any building modifications that alter foundation integrity, ventilation patterns, or ground contact -- including renovations, additions, and HVAC system changes

3. Mitigation and Reduction Systems

• Install active sub-slab depressurization systems -- the most common and effective method -- which use a fan and pipe to draw radon from beneath the foundation and vent it above the roofline
• Seal visible cracks, gaps, and openings in the foundation as a supplemental measure, recognizing that sealing alone is rarely sufficient to achieve safe levels without active depressurization
• Design new construction with radon-resistant features including gas-permeable layers beneath slabs, sealed vapor barriers, vent pipes, and junction boxes for future fan installation
• Verify mitigation system effectiveness with post-installation testing and monitor system operation continuously using U-tube manometers or electronic pressure indicators

Building Your Safety Mindset

1. Test Every Building You Occupy

   • Never assume that your home or workplace is safe from radon based on neighborhood testing, building age, or geographic generalizations -- only direct testing of your specific building provides reliable data
   • Retest every two to five years even if initial results were low because soil conditions, building settlement, and structural changes can alter radon entry over time
   • Test both residential and commercial spaces, recognizing that many workplaces -- especially those in basements or ground-floor spaces -- have never been assessed for radon

2. Act on Results Without Delay

   • Treat radon test results above 4 pCi/L as requiring prompt mitigation rather than further study -- every month of delay adds to cumulative exposure and cancer risk
   • Understand that radon mitigation is a proven, relatively affordable intervention that typically reduces indoor levels by 80-99% when properly installed
   • Communicate results to all building occupants so they can make informed decisions about their exposure and advocate for timely remediation

3. Make Radon Awareness Permanent

   • Include radon testing in every real estate transaction -- both buying and selling -- to ensure that new occupants have current data on their exposure risk
   • Monitor active mitigation systems regularly by checking the system pressure indicator and listening for fan operation to confirm continuous protection
   • Recognize that radon awareness has historically been low despite it causing an estimated 21,000 lung cancer deaths per year in the United States -- share your knowledge with others

Discussion Points

1. Why do you think radon testing remains uncommon in many homes and workplaces despite the well-documented cancer risk, and what would motivate more people to test their buildings?

2. How should landlords and employers be held accountable for radon testing and mitigation in buildings where tenants and workers have no control over the building envelope?

3. What role should local building codes play in requiring radon-resistant construction features in new buildings, and how would you implement testing requirements for existing structures?

Action Steps

• Purchase or request a radon test kit for your home and workplace if testing has not been performed within the past two years
• Check your building's foundation for visible cracks, gaps around pipes, and unsealed sump pits that could serve as radon entry points
• If a mitigation system is already installed, verify it is operating by checking the system's pressure gauge or manometer and confirming the fan is running
• Research your area's radon zone classification using the EPA radon zone map and share the information with neighbors and coworkers who may be unaware of the local risk