My Radon Testing Experiences

I'm using the Corentium Home Digital Radon Detector to continuously monitor my basement living area for radon gas in White County, Georgia.  I chose to use this product during my home inspection when I purchased the property in Sep 2018.  The cost of the Corentium Home was about the same as fees charged by certified radon gas testers and does not involve sending anything to a lab.  Plus, it was a challenge to find anyone willing to perform a radon test with an active test unit such as the SunRADON Model 1030.  I have a few words below about radon testing during real estate due diligence periods.

My Radon Test Results Sep 2018 to Nov 2020:

Long Term Average (24 months)	2.47 pCi/L
Short Term Average (1 and 7 days)	1.59 - 4.90 pCi/L

The Corentium Home screen has a black dot indicator in the upper right corner that appears when the unit is active.  The long term average reading is the radon level average since the unit was first calibrated or reset.  The short term average reading will alternate automatically between a 1 day and 7 day average.  The 1 day  average represents the previous 24 hours from the current time.  The 7 day average represents the previous 7 days from the current time.  The Corentium Home requires 24 hours to calibrate before displaying the measured radon levels.

I ran my test with the Corentium Home device for two years with the same three AAA batteries included with the product.  The images below are with new batteries and reset counters.

I installed ecobee3 lite thermostats in Jan 2020 which gives me the capability to automatically run my HVAC fan for a set period of time each hour when the heat or air conditioning function does not run.  This keeps air flowing, and the radon levels seemed to stay slightly lower.  I noticed the weather seemed to have an impact on the levels.  Levels were considerably higher when it was raining and the outdoor humidity levels were high.  Radon levels would occasionally peak above 4 pCi/L during rainy weather and high outdoor humidity readings (>80%).

Government and Industry Recommendations

The United States EPA guidance suggests mitigating if levels are at or above 148 Bq/m³ (4 pCi/L) and "consider fixing if your level is between 2 and 4 pCi/L".  When I checked into radon mitigation services, I did not find any certified mitigation companies that would warrant their work to reduce radon levels below 4 pCi/L.  The one radon mitigation company that responded with their warranty information said they guarantee the radon level 12 month average not to exceed 4 pCi/L.   See the EPA's Radon website for more information.

Depending on the country, the WHO's acceptable radon levels vary. A generally accepted action level established by the World Health Organization, the WHO, is 100 Bq/m3, or 2.7 pCi/L. Homes or structures measuring higher are advised to take remedial action to lower radon levels. The WHO further advises an upper limit that should not be exceeded at 300 Bq/m3, or 8 pCi/L.

Source: Airthings

The Georgia state radon program is run by the University of Georgia.  This program is a good resource for radon testing and mitigation in Georgia.

As a sanity check, I performed a short term 48 hour, activated charcoal test with Alpha Energy Laboratories.  The results were similar to the reading observed on the digital radon detector during the same time period.

Summary

Over a two year period, the digital radon detector showed long term readings below the "recommended take action" level of 2.7.  I saw several readings that exceeded 4 pCi/L and occasionally (maybe 2 before fixing the HVAC) saw readings of 6 pCi/L.

A typical home purchase due diligence period is 10-15 days.  This may not be enough time to get a reliable radon reading.  Fortunately, the EPA guidelines include how to deal with short term test results that exceed 4 pCi/L. 

Buyers and Sellers should consider the time needed to get a valid radon test(s).   Buyers should make sure they understand the guarantees offered by the radon mitigation company.  Some radon mitigation companies will only guarantee radon levels less that 4 pCi/L averaged over a 12 month period.  

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Update 5 Dec 2020:

Restarted Corentium Home radon detector on 16 Nov 2020.  Readings are showing 1 day averages below and near 1.0 pCi/L. Long term average is 2.10 pCi/L.  Humidity levels have been consistently below 50% (5-Dec-2020: humidity 44%, temp 66 F) in the room where the radon detector is located.

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Update 18 June 2021:

A trend is starting to emerge.  Radon levels start to spike as humidity levels increase above 60%.  A 50 pint dehumidifier with pump will be installed in the basement this month to maintain basement humidity below 50%.