Radon: Level detection, risk determination, and as-needed mitigation

Odorless. Colorless. Tasteless. But certainly not harmless. Radon, in both air and ground water, is a health risk whose prevalence should be regularly assessed and, if necessary, dealt with.

Beginning last fall and continuing through early summer, my community built an emergency access road that links up with a state highway below us and provides an alternate escape path in case of fire or other calamity, a particularly appealing option for those (like me) whose homes are at the far end of the community.

Road construction involved, among other things, the use of dynamite to blast pathways through rocky hillsides. And shortly after road completion, I learned that a residence a few minutes’ walk away from us had tested positive for high radon levels and was in the process of installing a mitigation setup.

Were the two events—earth disturbance due to road construction and radon release—related? I don’t know, and I’m not forward enough to ask the neighbors, but it’s possible. Regardless, even though our home had successfully passed a radon test done as part of the pre-purchase inspection more than a decade ago, I was motivated to learn more about radon and then re-test the premises for myself to see if the situation had subsequently evolved in an adverse direction.

Uranium and radium decay

As usual, I began my education with a visit to Wikipedi’s radon entry.

Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only ²²²Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. Radon isotopes are the immediate decay products of radium isotopes.

Here’s more.

A common source of environmental radon is uranium-containing minerals in the ground. Radon can also occur in ground water, such as spring waters and hot springs. Radon trapped in permafrost may be released by climate-change-induced thawing of permafrosts, and radon may also be released into groundwater and the atmosphere following seismic events leading to earthquakes, which has led to its investigation in the field of earthquake prediction.

Seismic events leading to earthquakes…and possibly also dynamite blasts? Here’s where the prose turned worrisome.

Epidemiological studies have shown a clear association between breathing high concentrations of radon and incidence of lung cancer. Radon is a contaminant that affects indoor air quality worldwide. Because radon is denser than air it accumulates in basements and crawlspaces under dwellings. According to the United States Environmental Protection Agency (EPA), radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to EPA policy-oriented estimates.

And finally, there’s this from the related Wikipedia entry for radon mitigation.

There is no proven link between radon in water and gastrointestinal cancers; however, extremely high radon concentrations in water can be aerosolized by faucets and shower heads and contribute to high indoor radon levels in the air.

Yikes!

Radeon prevalence varies across the United States and, more broadly, the world at large. It turns out that Denver, Colorado and surrounding regions have among the highest U.S. concentrations, as the following two related graphics show. The first documents the predicted fraction of U.S. homes having concentrations of radon exceeding the EPA’s recommended action level of 4 pCi/L. Note the orange region smack dab in the middle of Colorado, right where my residence is located.

And then there’s this one, which though formats the data slightly differently, but ends up with the same essential outcome.

The most concise and clarifying data I came across related to my specific situation comes from an informative page (highly recommended read, even if you’re not a neighbor of mine) on the Jefferson County website.

Approximately 50% of homes in Jefferson County test above the EPA action level for radon every year.

It’s followed by this.

Radon is found throughout the U.S. and is particularly prevalent in Colorado. The U.S. Environmental Protection Agency (EPA) has ranked Colorado as a Zone 1 area, meaning the average house will exceed the EPA’s action level for indoor radon.

Once again: yikes! I guess that’s why I see mitigation setups (more on them later) like this one all over the community.

Testing scenarios and equipment options

The Jefferson County webpage on radon also includes these non-scientist explanation statements that I thought were enlightening.

Radon is an invisible, odorless, tasteless, cancer-causing gas that comes from the natural radioactive breakdown of uranium and radium in soil, rock and water. Radon enters buildings through cracks, holes and pipes in the foundation. All buildings contain some radon, but homes are the most concerning since that is where families spend most of their time.

There’s also this.

Radon is produced as a decay product from uranium and radium. This naturally occurring radioactive gas is found in most soil, rock, and groundwater. Since radon is a gas, the inert element can easily travel through cracks and pores without being chemically bound or attached to other elements. Voids and porous materials are found under every building, allowing radon easy entry.

Perhaps obviously, once again quoting from the Jefferson County website, “the test kit should be placed in the lowest occupied level (typically a basement) and in the normal breathing zone (about 2-6 ft. from the floor) and 3 ft. from windows, doors, vents, or anything that allows airflow.”

Preferably, in fact, windows, doors (especially screened) and other outside-air ventilation sources should be shut as much as possible through the entire multi-day testing cycle to minimize gas dilution and maximize negative pressure (aka, “stack effect”) flow into the home, thereby simulating the worst-case radon accumulation that would normally occur in winter and other closed-off times (that said, air conditioning systems are another common catalyst for high radon gas leakage into buildings).

Free radon test kits are available to me from both Jefferson County and the Colorado Department of Public Health and Environment and can also be bought from local hardware and home improvement stores and online retailers. Keep in mind, however, that the kit still needs to be sent in for post-test analysis, with results subsequently sent back to the submitter, all steps incurring delays.

Yet another gizmo-acquisition opportunity

Instead, especially since I’m a techie who can’t resist new toys, I decided to buy my own radon detector hardware. The Airthings Corentium Home 2 (stock photos and promo video follow) normally costs around $180, but I found one promotion-priced on the Resale (formerly Warehouse) area of Amazon’s website for $121.46.

Versus its first-generation predecessor, it supplements the integrated display with Bluetooth LE and SmartLink (Airthings’ proprietary wireless protocol) connectivity to a separate device.

And battery life extends from 1.5-2 years (3 AAA alkaline batteries) with the original Correntium to 2-3 years (two AA alkaline batteries).

Here’s my own unit, starting with outer packaging shots.

Now open, with the contents accompanied by a 0.75′′ (19.1 mm) diameter U.S. penny for size comparison purposes.

Inside, of course, is the Corentium Home 2, along with some literature (also found online here) and a silica gel packet.

Here’s the open backside; batteries are included, with only a thin slip of plastic needing to be removed to complete the connection. Activate them as the power source and start testing.

Mating and initial setup of the device with my smartphone—which subsequently receives periodic notifications from it—was uneventful.

And, after a preparatory 24-hour delay over which the device collected and averaged (but did not yet share with me) its initial data set, preliminary results were encouraging.

I kept the measurements going for nearly three weeks before capturing another screenshot set, and the good news thankfully kept coming.

The application (Android in my case, but iOS also available) displays trend graphs, too, useful to see how radon levels, along with also-measured humidity and temperature, varied over time.

Mitigation methodology

All well and good, though I plan to continue conducting going-forward measurements, since radon gas levels vary over time due to a variety of factors. But what if my results had been more concerning? Step one is to seal off as much as possible any soil-sourced radon gas leakage coming into the house through slab and foundation cracks; more substantial slab voids resulting from floor drains and sump pumps are also potential culprits, albeit harder-to-eliminate ones.

Next, strive to minimize negative pressure (stack effect) scenarios or situations where the inside-house air pressure is lower than that of the outside, generating a partial vacuum condition that pulls air in from below the residence in attempting to equalize the differential. Frequent, vigorous use of HVAC systems is a potential root cause of pressure imbalances, along with attic fans, bathroom and kitchen-cooking-appliance exhausts, and the like. Keeping windows and screen doors open whenever weather and broader seasonal temperatures afford this option, as earlier mentioned, is helpful albeit only as temporary workarounds.

The most significant mitigation measure, and one that per my earlier shared photo I see frequently around my community, involves the installation of an active soil depressurization system. A PVC pipe originating below the home’s foundation, commonly in combination with a continuously running inline fan, draws radon gas out and up to the roof where it’s safely exhausted, completely bypassing the residence interior (and its inhabitants) in the process.

A tutorial video I found online showcases an in-home mitigation system installation.

I found it interesting for two main reasons, among others:

• The system’s location: I’d previously only been familiar with exterior-visible setups such as the one in the earlier-shown photo. I now wonder how many more homes in my community have implemented radon mitigation, internally (and therefore invisible to me from the outside) in these latter cases.
• And the initial, albeit unsuccessful, attempt to rely solely on a passive system, later supplemented by an active fan to create sufficient incremental suction.

I’ll wrap up here and turn it over to you for narration of your radon-related experiences and broader thoughts in the comments. Thanks as always in advance for them!

—Brian Dipert is the associate editor, as well as a contributing editor, at EDN.

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