My wife and I are looking to buy our first home. We recently found one, but a report says the radon levels inside the home are unsatisfactory. I've never really been aware of radon levels in homes before, but of course, look it up and it's not a good thing to have. :-/

  • What are the options that I have to mitigate radon levels in the home?
  • If radon levels inside the home are high, and a mitigation system is installed, does that mean radon levels outside the home will be just as high? What I mean is, are radon levels only a worry inside because they collect in an enclosed space VS outside in the open air where it's diluted?
  • The recent bad report has made me reconsider purchasing this home, even when negotiating price to compensate for radon mitigation. Is my worry justified? Or can installing a system fix it enough to where it's a non-issue?
  • Dont let it deter you from getting the house. Easily fixed and almost no risk once fixed.
    – mohlsen
    Nov 23, 2010 at 16:14

5 Answers 5

  • I gave a pretty detailed answer on radon mitigation systems in a related question. Rather than repeat myself, I suggest that you read that and follow the links, particularly the EPA's guide on radon mitigation for home buyers.

  • Radon levels outdoors are pretty much always going to be zero. It's only enclosed spaces you need to worry about.

  • As long as you can get a radon system installed without significantly destroying the home, and the radon levels aren't insanely high (100+ pCi/L), radon is not the end of the world. Tell the seller to pay for a radon contractor, or have them knock a few thousand off the selling price and hire your own guy. I would suggest getting a bid from a reputable radon contractor in the area so you know how much is reasonable for the sellers to concede. Make sure you also factor in the price of someone doing a re-test on the radon levels!

  • Thanks for answering each part of my question specifically!
    – Ryan Hayes
    Nov 23, 2010 at 16:37

The house I am living in now had high radon levels when tested before we purchased it. We negotiated in the purchase price to have the seller pay for radon mitigation. We hired a company to install the radon mitigation system. (Make sure you check their license. Most states have to license the installer. We learned a lesson there.) In order to put the system in, they drill a hole in your basement floor. There were two options for us, they could run the vent pipe out the side of the house or through the garage and up through the roof. We choose the garage option, because it looked nicer. The fan runs constantly to suck the radon out and vent it out the roof. They also sealed up the sump pump pit, so air could not come up through there.

You can get home radon test kits that you mail in. We test it about once a year, to make sure the levels are still below 4.

I don't think radon should discourage you from buying the house. It is very common in my area. A proper radon mitigation system is necessary to ensure your safety.


You can buy a radon mitigation fan for around $100 to install along with a vent pipe. Keep in mind that the lifetime cost will be more than the part's price, since you've got to run it continuously. You'll also want to check and make sure the fan reduces the radon levels below 4 pCi/L.

Here's a resource on figuring out what kind of power rating you'll need for a fan.
Also, here's a page on considerations before you start a DIY radon mitigation system install.


If the current owner is not open to purchace a professionally installed system and retest before closing, you must count on that expense yourself after you own the problem. Not a DIY project. I'm a certified home inspector and see a lot of buyers run away from houses in this situation.


There's no level of radon that has zero risk. (Note I didn't use the words "safe", which is a loaded word).

That sounds scary... we all want zero risk, right? Unfortunately, zero risk doesn't exist. Living is risk.

The official EPA number is 4 picocuries/liter. If you have a level above this, the EPA recommends you lower it below 4, and is called the "action level".

The "action level" numbers are different in different countries.

In the EU, this number is 8 picocuries/liter. In Canada the number is about 5.4 picocuries/liter. They used to be even higher in the EU and Canada.

The WHO has recommended an action level of 2.7.

That's crazy, right? Each country has the same data about the risks of Radon, has smart people making decisions, but the "recommended action level" varies by a factor of 2 or 3! Why?

Honestly, the numbers likely say more about each country and its culture than they do about the dangers of radon. Herein lies the problem with "no level of radon has zero risk". What does the official in each country say is "acceptable risk"? Zero is essentially impossible, since even outdoors you're being exposed to .4 picocuries/liter. So they pick a number based on whatever they arrive at as "safe".

So I can't tell you what "safe" is, since "safe" is relative (and obviously so since each country has decide different levels of safe). This is something only you can decide.

Just take into account that it's not like you're going to get cancer if you have a level of 7, and you're completely safe of you lower that number to 3.9. Neither are even remotely true. Canada, for instance USED to have a level of 22 picocuries/liter before 2007. I don't recall hearing about an epidemic of lung cancer in Canada in pre-2007.


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