Radon Gas — A Hidden Hazard in Your Home?

January 17, 2008

Our good friend and San Carlos resident Andy Blasband was kind enough to send along the following alert and useful information regarding Radon gas, and the dangers that it poses to homeowners. There is a link at the bottom of this post where you can get more information and order an inexpensive test kit. I was not aware of this potential health risk, but I am glad that I'm educated now. Thanks for the heads-up, Andy!


What is radon?
Radon is a naturally occurring radioactive gas. It is released during the natural decay of uranium, which is found in most rock and soil. Its occurrence in the state is influenced primarily by geology.

Where is radon found?

Although certain areas of the state are more likely to encounter radon problems than other areas, radon is a house-to-house issue. You may live in an area of low radon potential yet your house can have elevated radon while your neighbor's house has no radon.

Radon is odorless, invisible, and without taste, and cannot be detected with the human senses. The only way to detect it is to test for it.

Why should you care about radon?

Radon is the second leading cause of, following smoking. US EPA estimates that nationally 21,000 lung cancer deaths are caused by radon each year.

How does it get into my house and what can I do?

Air pressure inside your home is usually lower than pressure in the soil around and under your home. Because the pressure is lower inside, radon is sucked into your house through cracks or holes in the slab or foundation. If you have elevated radon levels you can fix your home. CDPH along with U.S. Environmental Protection Agency (US EPA) recommends that you if it has 4 picocuries per liter (4 pCi/L) or higher. If you are building a house in an area of moderate or high radon potential, we recommend using radon-resistant building techniques.

I am sending you this information because I conducted a short-term 48 hour radon test in our house last month and the level of Radon came back at 5.7 pCi/L. Currently, I have been instructed to conduct a Long-term test [1 year] to get average yearly radon level within many levels of our house. If the level of Radon remains greater than 4.0 pCi/L after a one year test we will need to take action to reduce the level of radon within the house.


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  1. Home owner_ Los Altos on September 26, 2013 at 6:04 pm

    Hi ! Great blog. Thanks.

    Just getting educated on the radon issue and found your post very interesting.

    Most home sellers and buyers don’t seem to know that the average radon levels around Santa Clara county are around 1.3 – 1.5.
    Given that, if a home owner has installed a radon mitigation system to reduce levels from 1.3 to say 0.5-0.6, will that bother prospective buyers? Or will they have enough context to understand that low levels (to begin with) were lowered even further?

    Our house has a level of 1.3. While that’s a good number per EPA standards (lower than 4.0 which EPA sees as the level at which it needs to be mitigated), we’d like to bring it down even further. Curious as to how future buyers may view our decision.. Do radon mitigation systems ever bother buyers or are they generally reassured that it’s been taken care of and brought down to levels that are even lower than EPA recommendations?

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