Does Your Home Have High Radon?

Public Domain. EPA

January is national radon awareness month. If you do nothing else, at least take a look at the map of radon risk zones above. If your home is in an area shaded red or orange, you may be especially at risk.

What is radon?

Radon is an invisible, odorless gas that can cause lung cancer. Although radon may be released from building materials, in most cases the source is natural radon found in the soils and rock on which your home is built. A house can act like a chimney: warm air rising inside causes a negative pressure in basements or at the slab level. This negative pressure can suck in gases, including radon.

How much radon is dangerous?

Once inside a home, the radon builds up due to a lower rate of fresh air inside the building. Radon levels outdoors average 0.4 pCi/L (pCi = picocuries). Although no level of radon can be considered totally safe, EPA recommends taking action to reduce radon if the level exceeds ten times this naturally occurring amount.Red areas (zone 1) in the map can be expected to encounter radon levels over the 4 pCi/L recommended level. Orange areas (zone 2) typically have between 2 and 4 pCi/L and should be tested. Yellow areas typically test below the 2 pCi/L level on average -- but only a radon test can assure you that your home is not the exception to the rule. You can get a better view by county if you visit the EPA radon zone map website and select your state.

radon test kit

© C. Lepisto

How to test for radon

Radon testing can be done cheaply, or even for free (we got the simple test kit pictured above for free). The cost and reliability depends upon the type of test used -- and, especially if you attempt do-it-yourself testing, how well the instructions for testing are followed. If your home has never been tested, a cheap test kit will tell you if you need to be concerned and save you the money on more reliable testing if the results come back low.

A passive radon test consists of an absorbent test medium that the user leaves in their home, usually for 48 to 72 hours for short term tests or several months for long term tests. Place the test medium in your home according to the instructions, typically in the lowest occupied level of the home, and leave it undisturbed for the duration of the test. Try to minimize the opening of doors and windows, or other unusual ventilation, in order to get a representative test. At the end of the test period, the test medium is sealed and sent in to a laboratory for analysis, usually at no extra cost once the test kit has been acquired.

If the test kit results are less than 2 pCi/L, you can stop worrying about radon. But if the level is over 2, it may be worth further study. If the level is over 4 pCi/L, you should definitely open your pocketbook for more testing to determine a course of action that may end in radon mitigation.

Radon monitor

Megan Khines/CC BY-SA 2.0

More reliable equipment will monitor the radon levels continuously, ideally checking also for temperature, pressure, and humidity which can indicate changes that might invalidate the test results. A certified tester must be employed to conduct a radon test with these relatively expensive monitors.

What does radon testing cost?

An internet search or call to your local lung association, energy efficiency programs, or State radon contact can shake out who has free test kits on offer. Otherwise these kits can be found for $15-20 at local hardware stores; check that the cost includes the lab analysis.

We surveyed costs in Minnesota (where new radon notification laws just came into effect for home sellers). Quotes for a radon test by a certified professional ranged from $75 to $200. The lower end of the cost range reflects the cost in the context of a package of services including other home inspection work. If you are asking for radon testing alone, you will probably find costs in the higher end of the range. Search at the National radon proficiency program (NRPP) or the National radon safety board (NRSB), or ask a local real estate agent (companies doing home inspections for real estate transactions often offer this service) if you cannot find someone online.

Radon mitigation warning

Eneko Lakasta/CC BY-SA 2.0

Radon mitigation, or what should you do if you have high radon?

The question of how to best reduce (or mitigate) radon levels in your home is complex. But here are a few buzzwords to help you figure out if the company making recommendations to you is on the up-and-up.

  • Sealing: be careful. If your contractor is recommending only sealing to keep radon gas from leaking into your home, they are probably not up to date on the latest research that indicates sealing alone is not effective.
  • Home pressurization (ventilation by fan): ask your contractor about the risks of mold as a consequence of moisture and evaluate the energy costs of bringing air in from outside to pressurize your home. A heat recovery ventilator can help introduce more fresh air at lower energy cost.
  • Suction: this word is your cue that your contractor is talking about one of the most effective methods of reducing radon levels. Different techniques for different foundations muddy the alphabet soup of methods, but all of these techniques rely of the concept of sucking air out from under the basement/slab/crawl space and venting it (usually by pipe) to somewhere above the roof. This reverses the negative pressure, so air is drawn out of your house rather than into it, and ventilates radon well out of the way of human breathing spaces.
  • Radon in water: a radon professional will check whether your water is also a source of radon, especially if you have a well.
  • Since it is cheap and easy to get a simple check on radon in your home, why not take the time to pick up a kit today? If you are in the market for a home, be sure to get a radon test in the purchase agreement and test before you buy -- you can make the seller pay for installing radon mitigation systems if levels are high; or invalidate the purchase agreement based on the high radon and look further for a house that is safe. If you already own your home, you should be able to reduce radon levels for about the same cost as other common house maintenance projects. Isn't your health worth it?