Hi, I’m Christy Walton with RE/MAX Select in Portland, Oregon. Welcome to Select’s Home Science School. Today, we’re talking Radon.
What, exactly, is Radon?
Radon is produced by the radioactive decay “daughter” of radium, which is itself a daughter of uranium and is common in all soils and stone. The radon naturally escapes from the soil or rock where it is generated and enters surrounding water and air or is generated during uranium ore mining or in the production of uranium fuel (but that’s a different story.) Its most stable isotope, radon-222 has a half-life of 3.8 days, which is relatively fast, but because uranium and radium are so prevalent in the Earth, radon will pretty much always be an issue.
Some of radon’s own decay daughters have exceptionally short half-lives and it emits ionizing radiation in the form of alpha particles, as well as beta, and gamma particles. They are solids.
What’s the problem?
Radon is radioactive. Unlike its parent elements, radon is a gas under standard conditions – an inert, heavy, noble gas. Radon is colorless, odorless, and tasteless, which means that it isn’t detectable by normal human senses and people don’t know that it’s there and they don’t know they are inhaling it.
When radon is inhaled, most is exhaled. Radon is constantly decaying, even during our respiration. The alpha particles shed by radon daughters can’t travel far and can’t penetrate the skin but as electrostatically charged solids, they attach to dust particles and cling to the lungs, invading cell nuclei, and doing damage that can lead to lung cancer or chronic lymphocytic leukemia. Stomach and other internal organ cancers are the results of radon-contaminated water. Research suggests that children who live in homes with high radon levels may have an increased risk of developing childhood acute lymphoblastic leukemia.
Per the Environmental Protection Agency, “Radon has been classified as a known human carcinogen and has been recognized as a significant health problem by groups such as the Centers for Disease Control, the American Lung Association, the American Medical Association, and the American Public Health Association.” Epidemiological studies have shown a clear link between breathing high concentrations of radon and the incidence of cancer.
The National Academy of Sciences stated that radon is the second leading cause of lung cancer after smoking and is responsible for between 15,000 and 22,000 lung cancer deaths every year. To bring that home, that’s about 58 deaths per day. Radon is the number one cause of lung cancer in non-smokers; about 2,900 lung cancer deaths occur among people who have never smoked. There are approximately 180 U.S. deaths per year from radon contaminated well water. Also, the relationship between radon and smoking is synergistic, meaning that smokers with exposure to radon have an even higher incidence of lung cancer.
Before you ask, with current technology, radon in human tissue is not detectable by routine medical testing. However, several of its decay products can be detected in urine, in lung and bone tissue, and by breath tests.
In Europe, radon concentration in the atmosphere is usually measured in becquerel per cubic meter. In the U.S. we measure in picoCuries with one picoCurie per liter of air equaling thirty-seven becquerel per cubic meter of air In the mining industry and when specifically discussing radon daughters, radon is measured in Working Levels.
As the map displays, radon concentration can differ widely from place to place. The red zone shows a county-wide screening average greater than 4 pCi/L, orange is between 2 and 4 pCi/L, and yellow is the lowest risk, at under 2 pCi/L. What the map doesn’t show is individual neighborhoods and homes which vary depending on hyperlocal geology, season – levels test higher when we heat our homes, atmospheric conditions, the structures built upon the earth, or if you’re standing in a uranium mine but is never zero. The Portland metro area is lit up bright red.
In the U.S. outside air typically contains very low levels of radon (about 0.4 picoCuries per liter of air). It builds up to higher concentrations in indoor air. The typical U.S. household concentration is 2.7 pCi/L. In Portland, we see levels vary from house to house and neighborhood by neighborhood. Large buildings that have many rooms may have varying radon levels in each room, even on the same floor.
The Environmental Protection Agency (EPA) set an action level of 4.0 pCi/L in homes and schools. In 1988, EPA and the U.S. Surgeon General issued a health advisory recommending that all homes below the third floor be tested for radon and fixed if the radon level is at or above 4 pCi/L, EPA’s national voluntary action level. The World Health Organization recommends that a home be mitigated when the radon level is 2.7 pCi/L (100 Bq/m3) or above. The American Society of Heating, Refrigeration, and Air Conditioning Engineers has set the lowest level, which suggests a radon action level of 2 pCi/L or less for commercial buildings and residences. The U.S. Mine Safety and Health Administration suggests the action level at 16 pCi/L (while miners are in underground mines). If you’re wondering why 4 was chosen by the EPA, I am happy to privately share a link that explains the costs of mitigation vs. medical costs.
As a note, 1 pCi/L of radon is equal to 2.5 cigarettes a day. The amount of radiation in 4.0 pCi/L of radon is equivalent to that in 100 chest X-rays and most hospitals only allow people to have four chest X-rays or .64 pCi/L each year. If a family whose home has radon levels of 4 pCi/L is exposed to approximately 35 times as much as much radiation as the Nuclear Regulatory Commission would allow if that family was standing next to the fence of a radioactive waste site.
Radon can enter your home through well water and in building or decorative materials made of concrete, stone, sand, or clay, with granite and concrete blocks being the biggest contributor of radon emanations from normal building materials.
In reality, most radon seeps up from the ground and concentrates in structures, like your house. Radon typically moves up through the ground to the air above and through cracks, holes, and pores in the foundation, joists, walls, and around pipes. It comes in through floor drains, unsealed sump pumps, and crawl spaces. Any place in your home that has contact with the earth is a possible entry point for radon. As a reminder, radon is invisible, odorless, and tasteless and most homes don’t have a sign flashing RADON PRESENT. So, we test for it.
There are two types of tests: passive and active. This is a passive test. I set these two bottles out in the lowest level of my home, seal the room for 2 to 90 days depending on the test, then send the test to a lab for analysis. No special training is needed for somewhere between $30-$50.
While home improvement stores do have do-it-yourself kits like this one, as a REALTOR, I highly suggest that homeowners hire someone to do the test for them to avoid any potential errors in setting, sending, or reading the test. I have a list of radon companies and home inspectors that I have worked with, but a quick search online will find someone.
Professional radon inspectors utilize active testing. The machines need power and can run constantly or take periodic measurements of both radon and atmospheric conditions over a specific amount of time, at least 48 hours. These tests can be both short and long-term if you want to make that investment. We tend to use a 48-hour test in our home buyer real estate inspections. The results are instant, but they are more expensive than a passive test. Also, small digital testing machines are available for purchase by homeowners.
If your home tests higher than 4 pCi/L, you should retest, just to be sure. You don’t want to take the next steps without knowing the levels.
So, now you’ve tested, what comes next?
If radon levels are over 4 pCi/l or the level that the homeowner requires, radon can be reduced. The EPA generally recommends methods that prevent the entry of radon, in one of four ways.
The most often utilized method is sub-slab-depressurization, also called soil suction or active soil depressurization by increasing under-floor ventilation.
- Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms
- Installing a radon sump system in the basement
- Installing a positive pressurization or positive supply ventilation system, but that could actually backfire and draw more radon into the building.
There are advertised and lab-tested techniques for reducing the radon entry rate due to off-gassing or “exhalation” from natural product building materials, including aluminum foil, paint, and other sealants. However, there are predictable failure responses from most of the surface treatments. Sealing alone has not been found to work consistently or effectively.
Treatment systems using aeration or activated charcoal are available to remove radon from private wells.
When it comes to radon that seeps into the home from the ground, there are two types of mitigation systems – active and passive. The things to consider when choosing the correct system include estimated lowest radon levels, installation costs, operational costs, fan noise considerations, and the appearance of the system on the home.
A passive radon system is pretty much a pipe without an exhaust fan. A passive system typically runs from the basement floor, sump pit, or drain tile and exhausts through the roof. Passive radon systems rely on what’s referred to as the “stack effect” (which is actually one of the ways that I cool my house). What happens is that warm air rises, and cold air is brought in from outside. That cold air contains radon. The stack effect relies on air pressure differentials to move air and radon gas through the pipe from under the basement to the exhaust vent. It does work – in a perfectly sealed home where the cold air flows directly into the passive pipe. The stack effect, while it does cool your home, usually is not enough to significantly reduce radon levels and can make them worse.
An active radon mitigation system has an electric fan running 24/7 to create constant negative pressure throughout the system. The amount of electricity used is about the same as a traditional light bulb, depending on the size of the fan. The negative pressure pulls the radon from the soil beneath the house and through the radon system pipes where it vents it above the roof. It can reduce radon levels by up to 99%. One company even guarantees a post-install radon level of 1.7 pCi/L!
In homes with crawlspaces, a sheet of high-density plastic is laid on the earth as a radon barrier, and the suction pipes are laid beneath that to vent to the atmosphere. This type of soil suction is called submembrane suction.
The process of installing the mitigation system involves answering questions about location, soil composition, negative pressure, and suction. The company may need to core the basement floor to take readings. They will then create a lateral suction hole (hopefully outside) to test and build the system and then figure the size of the pipe and fan required because of the soil composition, then install them. It’s important to get the right sizes so there isn’t electrical waste, excessive noise, or risk of back drafting. During the installation process, the EPA demands that certain foundation cracks are sealed with polyurethane caulk to help create the vacuum needed for the mitigation system to work.
If your basement is unfinished, now’s the time to prep it to protect your family from radon. Look online to learn how.
The final note on radon is that homeowners should test every two years because levels and conditions change.
I’m Christy Walton with RE/MAX Select. If you have any questions about radon or the Portland real estate market, drop me a line at GoodnightChristy.com. Also, hit the like and subscribe buttons then check out my other videos on the fascinating world of real estate in Portland, Oregon. If you are looking for my research citations, check out my blog at ChristinaWalton.com
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