Certified radon testing means that your radon results are interpreted by a person who has completed training provided by a US EPA regional radon training center and passed a rigorous national exam. In addition certified radon testing also means:

• The test results, tester placement protocols, maintenance procedures, storage procedures etc. are all subject to a detailed internal quality control program. 
• The electronic testers/monitors are calibrated, background and/or performance checked regularly by a certified calibration facility.
• The electronic testers/monitors receive annual maintenance reviews and repairs.
• The electronic testers/monitors are limited in the number of hours they can be exposed to higher radon levels annually.
• Onsite testing procedures and requirements are reviewed verbally and with handouts ensuring all requirements are understood and not violated for the duration of the test.  

We recommend the use of short-term electronic “Continuous Radon Monitoring” for the following reasons:

• The tester/monitor will provide 46-96 readings over the 2-4 days testing period, versus the 2 readings from charcoal canisters.
• The tester/monitor has built-in tamper resistant features indicating if it was moved and/or loses power. This is vital for our QC program ensuring the tester was not relocated to upper floor levels where radon concentrations are often less.
     ° Charcoal canisters have no controls for monitoring movement after the test has begun.
• The results of the electronic test are known as soon as the test is completed.  Results from a charcoal canister take several days. The charcoal canisters must be mailed to a lab and the lab must generate its report.
• The tester/monitor with its 46-96 readings will give an overall impression of home’s Source Strength/Ground Concentration of radon.

How is the Source Strength/Ground Concentration of radon affected by the weather and the time of year?
The ground for the most part is at a higher barometric pressure than the atmosphere we breathe. Air and radon gas are continuously coming out of the ground. During periods of strong winds and/or storms the barometer is typically lower. The pressure differential between the ground and the atmosphere (during storms/winds) will be higher. Gases/fluids naturally go from a high pressure to a low pressure. This greater differential in barometric pressures between the atmosphere and the ground will increase the likelihood of higher quantities of air (radon gas) coming out of the ground and potentially enter the home below the concrete slab. Factoring in the potential higher source strength with the barometric pressure differential, radon concentrations could be noticeably higher still. The specific highs and lows may peak and ebb constantly during the test. In addition to source strength, the time of year (snow/frozen ground) blocks the normal exit of radon gas thus increasing the potential below the unfrozen basement or main level slab. Proximity (closeness) to source strength is important. If you live in a home with only a slab (no basement) you could easily still have a high radon reading.  Besides source strength, proximity to the source strength, weather events, and time of the year, openings (holes/cracks, etc.) in the floor may also contribute to higher radon concentrations. Small cracks/holes, depending on source strength can noticeably increase radon levels. Taking into account all the variables mentioned radon levels can range from less than one to double digits during a short-term test. Charcoal canisters with only 2 readings will not detail the extremes our electronic testers/monitors produce, thus are a less informative method of testing.

Need more information on certified radon testing?

Please visit http://www.radongas.org/ (National Environmental Health Association – National Radon Proficiency Program (NEHA-NRPP)

Charcoal Canisters (short term test): - Tests purchased through your local hardware store and/or county health department
Professional Home Inspection Company discontinued testing with charcoal canisters in 2005. Charcoal canisters are an accurate, acceptable means of testing for radon but are limited to only two readings compared to electronic testers/monitors which will produce hourly readings for the 2-4 day test. Please read the above information related to “Source Strength/Ground Concentration for more information.

Alpha Track Test (long term test):
In the case where a long term test is desired, an Alpha Track canister is placed in the home for 3 to 12 months. For this method, the detector is a small piece of special plastic or film inside a small container. Air being tested diffuses through a filter covering a hole in the container. As a generally preferred but not mandatory rule we prefer to run the tests for a longer period, generally 4-6 months in order to account for seasonal variations of our region.