Everything You Need to Know About Radon

Everything you need to know about radon
Credit: JCHaywire under license CC BY 2.0

Radon is an important topic for both home buyers and sellers to understand. While there are differing opinions as to the effects of radon, in a real estate transaction the only opinion that really matters is that of the potential home buyer.

Testing for Radon is so important that the EPA actually recommends testing for all homes. As a buyer, you certainly want to test before closing on a home. Even if radon isn’t important to you, it might be to a future homebuyer, it’s better to know where you stand when it comes to radon.

Although Radon is listed in the Colorado Seller’s Property Disclosure form as a hazard that must be disclosed if it is known to exist or ever have existed. If the home has never been tested or if the current owner isn’t aware of any prior testing, they most likely won’t disclose. This leaves it up to the buyer to discover if radon exists in the property.

The home inspection is the ideal time to get this testing done. Even if the home has an existing radon mitigation system in place, testing is an affordable insurance policy.

In the “Steps to Buying a House” inspections are the buyer’s opportunity to dig deep and get a clearer idea as to the condition of the property. The inspection phase of the real estate transaction is where the home buyer should deal with any radon-related issues.

The home buyer will most likely do a general inspection with a certified home inspector. This inspector should be able to perform a radon test at the same time as your home inspection. If they are not set up to do a Radon test, they will be able to recommend the appropriate vendor that can.

What is Radon?

Radon is a naturally occurring, inert, odorless, colorless, radioactive gas. It is formed by the radioactive decay of uranium in rock, soil, and water. So, without a test, there is no way to know if your home has it.

Radon moves through the soil, and into the air and into homes through small cracks and voids in the foundation. Homes trap radon in living spaces, where it may build up to dangerous levels.

What Does Radon Do?

Radon is right behind cigarettes as the second leading cause of lung cancer. Radon is associated with 15,000 to 22,000 lung cancer deaths in the United States annually.

Here is a good description, written by the National Cancer Institute of what Radon does to cause cancer.

Radon decays quickly, giving off tiny radioactive particles. When inhaled, these radioactive particles can damage the cells that line the lungs. Long-term exposure to radon can lead to lung cancer, which is the only type of cancer proven to be associated with inhaling radon. There has been a suggestion of an increased risk of leukemia associated with radon exposure in adults and children; however, the evidence is not conclusive.

Radon is actually a controversial topic and while there are many credible sources that question the effects radon has on human beings, the evidence and research that it is harmful are too overwhelming for us to ignore, especially when representing home buyers. Here is a list of organizations that state Radon is a health threat:

  • U.S. Surgeon General
  • American Medical Association
  • American Lung Association
  • Centers for Disease Control
  • National Cancer Institute
  • National Academy of Sciences
  • Environmental Protection Agency
Everything you need to know about radon
Credit: methodshop under licence CC BY-SA 2.0. Updated number of deaths per year.

Testing for Radon in Homes

Radon is listed as a hazard in the Colorado Seller’s Property Disclosure form and must be disclosed if the Sellers know that it exists or ever has existed.

Without testing, it’s not possible to answer this question but once the seller has been informed it is incumbent upon them to disclose. Once again the EPA does recommend testing all homes for radon.

Here’s the science of radon, levels are measured and talked about in terms of “Pico Curies” this is an international unit of radioactivity that is defined as 1 Ci = 3.7×1010 decays per second. This is approximately the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Pierre and Marie Curie, for whom the unit was named.

The important number to remember for the purposes of radon in a home is 4 pCi/L (pico curies per liter). This is the number above which the EPA recommends mitigation. It’s important to note that we often hear about higher acceptable levels in other countries, the point being the US is “unreasonably” low. This might be the case but as far as the United States is concerned 4 pCi/L is the magic number.

Radon in Colorado Springs

Testing for Radon is especially important here along the front range of Colorado. Radon is prevalent in the entire State of Colorado but especially high right here in Colorado Springs and El Paso County.

Radon tests are a regular part of Home Inspections in Colorado Springs, Manitou Springs, Monument and Fountain Colorado.

The Environmental Protection Agency (EPA) produces a “Radon Map“. This map categorizes areas into three zones to assess radon potential. All of El Paso County is in “Zone 1”

  • Zone 1- Highest Potential: These are counties that have a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter)
  • Zone 2- Moderate Potential: These are counties that have a predicted average indoor radon screening level between 2 and 4 pCi/L
  • Zone 3- Low Potential: These are counties have a predicted average indoor radon screening level less than 2 pCi/L

The criteria used to develop this assessment are as follows:

  1. Indoor radon measurements
  2. Geology
  3. Aerial radioactivity
  4. Soil permeability
  5. Foundation type

Testing Methods

There are essentially two different types of testing methods. Passive and Active. Passive testing methods capture radon or it’s related products which are measured later in a laboratory.

There are four types of passive collection methods: charcoal canisters, charcoal liquid scintillation detectors, alpha track detectors, and electret ion detectors.

Charcoal Canisters and Charcoal Liquid Scintillation Detectors

The charcoal based devices are considered a short term test. This type of test takes from 2 to 7-day to complete. The devices are left in the lowest level of the home where they trap or absorb radon or its related products. The charcoal based tests require testing at a laboratory in order to determine the results.

The Charcoal Canisters contain activated charcoal which absorbs radon. These canisters are taken to a laboratory where they are measured with a sodium iodide detector to determine the amount of radon.

The Charcoal Liquid Scintillation Detector, on the other hand, uses a photo-multiplier tube to detect and count the alpha particles in order to determine radon levels.

Unlike the Charcoal based tests, the Alpha Track Detector test is considered a long term test. This test requires a minimum of 8 days and a maximum of 365 days to complete. According to the EPA, long term tests the best way to determine radon levels over different seasons and living conditions and unlike the charcoal radon tests, the alpha track radon test isn’t affected by humidity.

Alpha Track Detectors contain a thin plastic film that is etched by alpha particles striking it. Once in the laboratory, this plastic film is chemically treated in order to make the alpha particle tracks visible. These tracks are then counted and a radon level is determined based on the results.

Unfortunately, the time required to complete this type of test makes it impractical for most real estate transactions.

Another passive radon testing method is the Electret Ion method. Electret ion detectors contain a statically charged Teflon disc. When ions generated from radon decay strikes this Teflon disc, the electrical charge is reduced. In the laboratory, the charge reduction is measured and the radon level is calculated.

Active Testing Methods – Continuous Radon Monitors and Continuous Working-Level Monitors.

Active devices differ from passive in that they require electrical power to operate. These devices record radon and related products continuously. Continuous devices are more expensive than their passive counterparts and require training but offer a more reliable reading.

These units are pretty much tamper-proof. If a homeowner moves the device or opens windows, in an attempt to affect the radon test readings, that change in temperature and barometric pressure will raise a red flag. Additionally, these units have an internal motion sensor that will detect and record any movement of the unit to a different location. Unscrupulous Home Sellers and REALTORS® have been known to move the testing equipment outside in an effort to get a clean test.

We prefer these Continous Monitoring test for a couple of reasons. First of all, they are more reliable than their passive, charcoal based counterparts because they aren’t as susceptible to humidity changes. Additionally, They aren’t easy to game, in other words, if someone messes with the unit, the inspector will know. Finally, we don’t have to wait for the results to come back from a lab. The continuous monitors produce results immediately, so we leave the inspection knowing the status.

How Does Radon Get Into Your Home?

Everything you need to know about radon
Credit: OpenStax

The primary entry point for radon into the home is through the foundation. If you have a basement, the gas can seep through small cracks and voids in the slab. Open Sump pits also create an opening for gases to enter the home.

Crawl Spaces which are generally left uncovered provide no barrier for radon gases either.

Sometimes radon enters the home through well water. When residents take showers the steam can carry radon throughout the house, as well. Here is a great article on “How to Remove Radon from Well Water”.

Mitigating Radon

There are a handful of different methods used to mitigate radon from a home. The most popular method here along the front range of Colorado is Active soil depressurization (ASD).

Active soil depressurization (ASD) essentially keeps radon gas from entering the home by changing the pressure differential, essentially depressurizing the force that pushes the gas from below the foundation slab or crawlspace into the home. Radon is drawn from beneath the slab by an exhaust fan that vents the radon gas through a PVC pipe up and over the roof of the home to the outdoor air where it dilutes into the atmosphere.

It’s important that radon mitigation systems vent above the properties roof. Since radon gas is heavier than air the possibility exists that the gas can be picked up and redistributed through the homes HVAC system. By venting above the roof the concentration of gas falls off significantly before it has the opportunity to be reintroduced.

It’s important to note that the active soil depressurization system is a separate system and is not related to your homes HVAC or any other system except that it draws a slightly low voltage feed from your electric system. So, the cost to operate an ASD system is low as well. The system fans typically use 90 watts per fan. The cost to operate one of these units is approximately $25 to $45 per year.

The cost of installation varies based on the size of the home and the type of foundation. Here along the Front Range of Colorado, systems run from $800 on the low end to $2,500 on the high end. Newer homes with perimeter drains tend to be easier for installation of mitigation systems and therefore cost less.

We test for radon during the inspection because it’s generally something we want the seller to pay for. In some cases the buyer may be willing to accept the cost of mitigation, this generally has to do with the purchase price and terms.

If the seller ends up installing the system it’s important to get documentation about who installed the system what the numbers look like on the retest and what the warranty is. All of this should be wrapped up prior to closing.

Frequently Asked Questions about radon:

Can radon levels change over time?

Yes, changes in temperature, Moisture and Dryness can cause the uranium levels to rise which results in an increase in radon levels. If the ground around your home becomes saturated, frozen or covered with snow, it keeps the radon in the ground not allowing it to escape. Wind can also change the pressure around your home, which could cause radon to diffuse into your home. It is recommended not to test during severe weather or high winds.

How often should we test?

If you have a system in your homes the EPA and IEMA recommend that you test every two years. How long do Mitigation Systems Last? Usually, the manufacturer warrants the fan for 5 years. The national average for the life of a fan is 11 years. Some last as long as 20 years.

Should we test for radon if a mitigation system is present?

Yes, if it has been 2 years since it was installed.

What is the cost of operating a mitigation system?

$25-$45 a year.

What is a Pico Curie?

This is an international unit of radioactivity that is defined as 1 Ci = 3.7×1010 decays per second. This is approximately the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Pierre Curie and Marie, for whom the unit was named.

What’s the fastest way to test?

The quickest way to test is with a short-term test. These kits remain in your home for two days to 90 days, depending on the device.

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