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Division of Environmental Health > Radiation Control Program > Radon

Radon & Home Sales

Real estate transactions are the wrong time to find out that there is high concentration of a naturally occurring lung cancer inducing radioactive gas emanating throughout your home from under it’s foundation…(or maybe escaping from your drinking water!). If not for the pre-sale home inspections that are typically requested by prospective buyers, very few people would have ever heard of this invasive and harmful gas. Unfortunately, this is often the first time the house has ever been tested for radon. In Maine, (statistically) one out of three homeowners are then told that the home they have been living in for years (if not decades) has a radon level that is unhealthy and unacceptable to the buyers, who subsequently propose as a condition of sale, that a radon mitigation system is installed at the owner’s expense . This sometimes jeopardizes the sale of the property to the dismay of the owner, seller, as well as the real estate agents involved.

Ensuring that real estate transactions are completed is certainly not the main goal of this agency. It is quite obvious, however, that the concern of an elevated radon level interfering with home sales has created an environment that is antagonistic to our efforts to inform and protect the public from this major environmental carcinogen. (According to National Academy of Sciences and the U.S. Surgeon General, radon is the second leading cause of lung cancer for non-smokers).

As an attempt to counter some of the confusions and phobias regarding radon and radon testing procedures, this page was developed. It is a brief synopsis of the more detailed guidance that can be found in our “Maine Home Buyers Guide to Radon” which is presently being revised.

Here you will find radon testing information for both the buyer and the seller of a residence, which can help clarify some typical issues that come up during a real estate transaction.

Radon and Real Estate Related Facts

  • Radon can be found in elevated levels (greater than the action level of 4 pCi/l) ANYWHERE in Maine. In fact, the average residential radon level in the state is 4.1 pCi/l, and even higher in the southern portion.
  • Generally speaking, there are two places that indoor radon comes from. Sometimes the radon in your home's air comes from the soil gasses, and sometimes it comes from the water. Sometimes it comes from BOTH places, but the presence of soil gas radon does not indicate or predict the presence of well water radon (nor does well water radon indicate or predict soil gas radon). Most of the radon in Maine homes comes from the soil gasses.
  • If your home is for sale, you cannot legally test for radon yourself. You must hire a state registered radon tester. For a current list, click on: http://www.maine.gov/dhs/eng/rad/radon/testers.pdf
  • If your home is for sale, you cannot legally install a radon mitigation system yourself. You must hire a registered radon mitigation contractor. For a current list, click on: http://www.maine.gov/dhs/eng/rad/radon/mitigators.pdf
  • If the home utilizes a well for its water supply, the water should also be tested for radon. In this case, testing means drawing a sample. Again, only a radon tester registered to collect water samples for radon analysis can legally do so in a home that is for sale. It is a violation of state law for the homeowner, prospective buyer, or the realtor to collect this sample.
  • The state of Maine Maximum Exposure Guideline (MEG) for radon in water is 4,000 pCi/l. At this concentration, consider your total radon exposure (from both water and soil gas), and decide which risk is more important to fix. As the concentration gets closer to 10,000 pCi/l, it becomes more important to fix the radon in water regardless of the concentration of radon in the air from soil gas. For a quick answer to "what do I do?", go to (for a detailed discussion of radon in drinking water, go to: Radon_Lab_Sheet08.pdf
  • Maine regulations require that a home for sale be tested in the lowest usable level– usually the basement. Other agencies, such as the EPA, also recommend this, because a buyer may choose to live in a lower area of the home than that used by the seller.
  • Even if there is a dirt floor in the basement, if there is evidence of habitual occupancy (for example; weights, treadmill, washer/dryer, workbench etc.) then this is where the detector must be placed.
  • Regardless of the level of radon in a home, it CAN be “fixed” (brought below the action level)
  • The amount of radon in your home does NOT determine the price of a mitigation system. A home with 100 pCi/l can be fixed for the same price as a home with 6 pCi/l.
  • If you are building a house, there are construction methods that will inhibit radon from entering. Maine recently adopted ASTM E 1465 "Standard Practice for Radon Control Options for the Design and Construction of New Low-Rise Residential Buildings" as the Maine Model Radon Standard for New Residential Construction. To get one free copy of this document from the US EPA, go here: http://www.epa.gov/radon/pubs/index.html.
  • A system to reduce the radon coming into your home from the soil (usually a “Sub Slab or Sub Membrane Depressurization System”) costs between 800 and $1500, and takes less than a day to install. A system to remove radon from your water supply costs about $4500. Obviously, it’s best to know BEFORE you purchase the house, if these systems are required, just as you would like to know if the roof, heating system, or septic system needs replacing!
  • Sealing and caulking is NOT an effective long- term method to reduce radon levels in your home. Please refer to the “Important Consumer Notice” on this topic: http://www.maine.gov/dhs/eng/rad/RNnotice.htm
  • There are ways to help insure that correct radon test conditions are maintained. (see the section: “Preventing or Detecting Test Interference” in the “Maine Home Buyers and Seller’s Guide” for details) One of the ways is to hire a registered radon tester who uses a Continuous Radon Monitor (CRM) or uses another type of device and some form of tamper indicator. A CRM records hourly readings that can indicate interference (intentional or unintentional) with the test. Tamper indicators can also provide signs of interference.

 

If you would like to discuss the specifics of your
radon situation, please call us at 1-800-232-0842
(in Maine), or 207-287-5698 (outside Maine) or email us at
Tom.Thornton@maine.gov

 

 

This table is taken from the EPA Publication, “A Citizen’s Guide to Radon”.

 

Radon Risk If You Smoke
 

Radon Level If 1,000 people who smoked were exposed to this level over a lifetime*... The risk of cancer from radon exposure compares to**... WHAT TO DO:
Stop smoking and...
20 pCi/L About 260 people could get lung cancer 250 times the risk of drowning Fix your home
10 pCi/L About 150 people could get lung cancer 200 times the risk of dying in a home fire Fix your home
8 pCi/L About 120 people could get lung cancer 30 times the risk of dying in a fall Fix your home
4 pCi/L About 62 people could get lung cancer 5 times the risk of dying in a car crash Fix your home
2 pCi/L About 32 people could get lung cancer 6 times the risk of dying from poison Consider fixing between 2 and 4 pCi/L
1.3 pCi/L About 20 people could get lung cancer (Average indoor radon level) (Reducing radon 
levels below 2 pCi/L is difficult.)
0.4 pCi/L About 3 people could get lung cancer (Average outdoor radon level)
Note: If you are a former smoker, your risk may be lower.
* Lifetime risk of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease Control and Prevention's 1999-2001 National Center for Injury Prevention and Control Reports.

Radon Risk If You've Never Smoked
 

Radon Level If 1,000 people who never smoked were exposed to this level over a lifetime*... The risk of cancer from radon exposure compares to**... WHAT TO DO:
20 pCi/L About 36 people could get lung cancer 35 times the risk of drowning Fix your home
10 pCi/L About 18 people could get lung cancer 20 times the risk of dying in a home fire Fix your home
8 pCi/L About 15 people could get lung cancer 4 times the risk of dying in a fall Fix your home
4 pCi/L About 7 people could get lung cancer The risk of dying in a car crash Fix your home
2 pCi/L About 4 person could get lung cancer The risk of dying from poison Consider fixing between 2 and 4 pCi/L
1.3 pCi/L About 2 people could get lung cancer (Average indoor radon level) (Reducing radon levels below 
2 pCi/L is difficult.)
0.4 pCi/L   (Average outdoor radon level)
Note: If you are a former smoker, your risk may be higher.
* Lifetime risk of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease Control and Prevention's 1999-2001 National Center for Injury Prevention and Control Reports.

 

It's never too late to reduce your risk of lung cancer. Don't wait to test and fix a radon problem. If you are a smoker, stop smoking.

 

 

FOR ADDITIONAL INFORMATION CALL THE RADIATION CONTROL PROGRAM AT:
207-287-5676