Healthy Home – Radon


Radon is a naturally occurring odorless, colorless, tasteless radioactive gas produced by the decay of uranium and radium in the ground.  It percolates up from the soil. Because it’s a gas, radon can move into water or air.

Radon is present outdoors and is normally found at very low levels in the outdoor air and waters of our rivers and lakes.  It can be found in much higher levels in enclosed spaces like your home or private well.  Once inside enclosed spaces, radon can accumulate.  Hence, radon levels inside tend to be much higher than those found outdoors. Due to the geological makeup of our region, it is estimated a quarter of Massachusetts homes may be at risk for high levels of radon.

The Environmental Protection Agency (EPA) has classified the states counties based on radon potential.  This chart shows Middlesex, Essex, and Worcester counties have the greatest risk for high levels of radon. I’ve also included a map of the US.

US Radon Map
US Radon Map



Radon is a carcinogen. It is the leading cause of lung cancer among non smokers, and the second leading cause of lung cancer overall. There are many sources of radiation, however radon is the largest.

Radon undergoes a radioactive breakdown, decaying into other radioactive elements resulting in the release of subatomic alpha particles. These stick to surfaces such as dust particles.  If this contaminated dust in inhaled, these particles adhere to the airways of the lungs overtime damaging the cells. It is estimated radon exposures cause 21,000 lung cancer deaths each year in the United States.

The EPA has established an action guideline, recommending mitigation for residences with radon concentrations at or above. 4.0 picocuries per liter of air  (pCi/L)


Radon testing is simple and inexpensive.  Radon test kits can be purchased at your local hardware store, on Amazon, online.  Kits typically cost between $10 and $40.  You want to get a kit with 2 vials as you’re checking for consistency.  Place both vials next to each other. Read the instructions on the kit carefully.  These tests are timed.  A typical test takes at least 48 hours.  Reseal the vials, note the vial numbers and mail back to the testing lab. Your results should be available on line 2-3 days after the lab has received your kit.

Radon Test Kit
Accustar Radon Test Kit

If you’re buying a home, it is important you make radon testing part of your inspection.  Most home inspectors can test for radon. Some inspectors have continuous radon monitors, providing hourly radon levels.  These cost a bit more than the vial kits, however your results will be available immediately after the 48 hour required testing time.

If your home tests over 4.0, don’t worry!  Mitigation systems typically get the levels under 2.0 pCi/L.


The process to mitigate is relatively simple. A method called active soil depressurization is typically used. A zone of low pressure is created below the slab, reducing the rate radon enters the home.  A fan and piping is installed sucking radon out from under the foundation and venting it into the atmosphere.  A system typically costs between $1,200 to $1,800.  Your homes design, size, and foundation may impact the systems cost.

After your system is installed, it is important to retest for radon.   Please give your new system a few days to clean the radon out.

Radoy System Monitor
Radon System Monitor

Also important – the radon mitigation system is a vaccume system.  Your systems pipe moving radon from your foundation to the outside air will have a tube of colored water.  The levels on both sides of the tube should be uneven.  This indicates the system is working.  IF both sides are even, please call a mitigation contractor.