Radon Mitigation

This article discusses the importance and effectiveness of radon mitigation. If you want to learn more about radon or need a refresher, check out my radon page.


Like many, I had my home tested when I purchased it. The average was 3.7 pico Curie per liter (pCi/L) so no mitigation was “required”. After a few years, I tested the home again to find the average was 5.7 pCi/L. But with a new baby in the home, thoughts about the radon level and everything else disappeared. Three years later, things have finally settled down and I circled back to the radon concerns and tested again only to find the average ranging from 11-26 pCi/L which was devastating. I could no longer put off taking action to make my home safer for my family. Luckily, I am trained on radon measuring, mitigation, and inspection of mitigation systems but that is not the case for everyone so I decided to write about my own home’s mitigation.

What does mitigation entail?

There are a few effective and proven mitigation techniques used by professionals to bring the radon level down. No matter the method used, the general idea is to seal off openings that let ground air into the home and to create a new path for radon gas to leave the ground. The most common solution will use a fan running all the time to create a suction under the home and blow it above the roof. By doing so, the radon will go this route instead of coming into the home.

Mitigation using the sump basin

To minimize disruption to the finished basement and keep the solution cost effective, I decided to mitigate using my sump basin which was conveniently located in the back corner of the basement.

As you can see, my sump basin was not sealed. Using the sump basin is not ideal as it can complicate maintenance and replacement of the sump pump; however, there are basin covers such as this one from Everbilt which uses seals and keeps the sump pump accessible.

The impact mitigation has on radon levels

radon test

The above graph reflects hourly radon readings for 40 days in my basement covering time prior to, during, and post mitigation. Marker 1 on the graph is when the basin cover was installed to seal off the sump basin which was letting in soil air.

The EPA indicates sealing cracks and openings alone is not an effective mitigation solution so not surprisingly, adding the basin cover did not have much impact on my radon level. Marker 2 on the graph indicates when the piping and fan was installed create negative pressure in the sump basin and drain tile.

Sump Basin Radon Mitigation

The radon levels started dropping within 4 hours of activating the fan. With the fan running for just 14 hours, the radon level went from approximately 16 pCi/L to below 1 pCi/L. Lastly, marker 3 on the graph is a 4.5 hours period the radon fan was deactivated. In just that short amount of time, the level increased to 3.1 pCi/L and took another 4 hours to bring down below 1 pCi/L again.

In conclusion, radon mitigation can effectively reduce the radon levels of a home no matter how high the levels or type of construction. In most cases, mitigation systems can be installed for about the cost of other moderate repairs to a home and can operate for less than $10/month in electricity costs. But as with everything in a home, things can break. Have your home radon level tested every 2-3 years to ensure your mitigation system is operating effectively.

As evidenced in my case, radon levels can and do change over the years. If you haven’t had your home tested in more than 2 years, I recommend calling or texting me at (443)559-7028 to discuss getting your home tested.

Published by Aaron Ankeny

Certified Professional Home Inspector Maryland Home Inspector License #33406 Maryland Association of Home Inspectors #53263870 International Association of Home Inspectors #NACHI19043023

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