Are Electronic Radon Monitors Reliable?
Sometimes.
In the last couple of years there has been a massive increase in the number of low cost, electronic radon testing monitors specifically marketed to homeowners. My question as a radon testing professional was, "How reliable are these monitors?" Especially since I've been getting more and more calls from homeowners telling me they have high radon in their home and when I ask how the test was performed they tell me they bought their own radon testing monitor. Professional-grade radon monitors in the United States need to be calibrated annually to ensure accurate results. After running long and short term, side by side radon tests with several types of radon monitors, I'm quite sure that some of them are not accurately calibrated if calibrated at all, because the test results vary wildly and most are far from accurate.
Cheap Radon Monitors Compared
The reliability of home radon monitors varies wildly! Buyer beware.
Earlier this year, I purchased 6 electronic radon monitors from Amazon, what I would call off brand models, marketed for homeowners, priced from about $79 to $150. In my radon mitigation business, I'm hearing more and more people who have purchased their own radon testing monitors to measure radon in their homes often to check the performance of their radon system and and they are not sure if there monitors are working properly or not, due to conflicting test results compared to other tests. Their new monitors were not in agreement with previous tests. After first ruling out whether the test was conducted properly or not, my question to them and for myself was, are these unbranded and new to the market inexpensive monitors giving accurate results?
My own follow up radon tests often proved many of these radon test monitors were wildly inaccurate. So, to confirm my initial findings, I decided to do some long and short term, side by side comparison tests with with monitors I know to be accurate. To aid in this comparison, in addition to purchasing several off brand radon detectors, I also purchased the EcoTracker set of 4 professional grade radon monitors sold as a 4 unit set for about $1,000. I would also include some of my other professional radon detectors that had current certifications for calibrated accuracy.
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The EcoTracker radon test monitors from Ecosense are professional grade designed for radon mitigation contractors, with proven accuracy to perform simultaneous diagnostic radon tests. They're manufactured and pre-calibrated in a controlled radon chamber using precision instruments to ensure immediate, accurate performance. They utilize a highly sensitive ion chamber sensor that delivers the exacting performance required by professional. I used these four monitors, freshly calibrated from the factory plus a Sun Nuclear 1028 professional radon test monitor with current certified calibration for my test comparison along side the 6 popular off brand radon monitors mentioned above. Additionally, to confirm my professional test monitors continue to be accurate and I regularly test them side by side with Air Chek certified test kits which are analyzed in a NY State certified laboratory.
The purpose of this post is to communicate is how unreliable some of the online, highly marketed radon monitors are. I've seen a trend with homeowners purchase digital radon monitors online, doing their own tests, assume the test results are accurate, but oftentimes are totally unaware their test results are far from accurate. Radon test monitors are not similar to a smoke alarm or CO detector that has a test button that confirms proper function. Proper function can only be assumed if the unit sold has reputable proven accuracy or it has been properly factory calibrated and certified or if it is tested side by side with a properly factory calibrated and certified professional radon test monitor or certified test kit.
In my side by side comparison test The 5 professional monitors over the course of several weeks measured daily and weekly average radon levels in a tight group between 3.5 to 4.2 pCi/L, which is within 25% accuracy of a know radon calibration value required for EPA accuracy certification. In contrast the 6 off brand monitors measured daily and weekly radon averages between 0.3 pCi/L to 42.0 pCi/L to 68.7 pCi/L, None of them ever measured daily or weekly averages with the 3.5 to 4.2 pCi/L of the professionally calibrated monitors.
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To summarize, the cheap non brand name, knock off monitors were in no way reliable. 6 of my proven reliable monitors, plus the 4 brand new professional monitors all of which had similar readings with less than 25% difference. I did several of these tests with similar results over a 3 month period.
For the side by side testing of the bench mark professional monitors, I used the set of four new EcoTracker professional monitors, just calibrated from the factory and my other certified and calibrated professional testing monitor, testing side. All these professional radon monitors tested within a tight group of 3.5 to 4.2 pCi/L, which is with in 25% accuracy required for certified accuracy. I did this bench mark testing of the professional radon monitors at the same time as the afore mentioned off brand radon monitors.
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I did several of these side by side, simultaneous tests with similar results over a 3 month period. I really wanted some of the cheaper monitors to work well, so I could recommend them, and I did purchase additional units of the same brands in case I got a bad one, but the results of most of them continued to be unreliable. Occasionally one or two of the additionally purchased off branded models were a little more accurate than others but that was rare and not consistant.
I will go into more detail at a later date with model names etc. But for now, what I want people to understand is that all radon monitors are not reliable, even though they look very similar, and have what appears to be the same specifications. I also want to note that these monitors I bought were some of the least expensive and new to the market with little or no reviews yet posted. I did some follow up a few month later, and the same monitors now had reviews, many of which were good reviews, but it seems most people doing the reviews had no way of knowing if the measurements were accurate or not and just accepted the given levels as correct. When I purchased the same monitors again at later dates, I had similar inaccurate results that varied greatly from side by side testing with calibrated professional units.
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True, professional-grade electronic monitors are factory-calibrated in tightly controlled reference chambers against precise, known radiation levels. Over time, all digital sensors naturally drift due to changes in humidity, temperature, and basic sensor degradation. Because of this, reliable, professional equipment must be sent back to a certified laboratory to be recalibrated after a set period, usually 1 year. If a radon monitor has no mechanism or program for factory recalibration, you have to wonder: Was it ever actually calibrated to an accurate level in the first place? The answer for many of these inaccurate and unreliable monitors purchased online is no.
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I'm not going to go into detail here, but another big factor in accurate radon testing is where and how the test is performed. If not placed properly and conducted properly, you will not get accurate results even if using the most accurate radon testing monitor. So be sure to follow proper radon testing protocol. ​​​​
How to Ensure Your Home is Truly Safe?
If you want to track your home's air quality without risking your family's health on a cheap digital gamble, follow these three rules:
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1 - Look for Certifications: Only trust electronic monitors approved by national proficiency boards, such as the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Brands like Airthings, Ecosense, and SunRadon undergo rigorous independent laboratory testing to prove their accuracy.
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2 - Start with Certified Lab Kits: If a professional, certified digital monitor isn't in your budget, stick to standard, single-use charcoal test kits. While passive, they are sent directly to an accredited laboratory for precise analysis, making them far safer than a cheap digital guessing machine.
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3 - Trust Professional Diagnostics: When installing or checking a system, always rely on professional testing equipment. At A Best Radon Systems, your family's safety is our absolute priority. We don't guess—we measure with precision. If you are worried about the radon levels in your home or want a definitive, professional assessment of your indoor air quality, contact our Central New York team today to schedule a certified test.
​Recommendations:
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As a professional radon mitigation company, our job at A Best Radon Systems doesn’t end when the pipe is glued and the fan turns on. Our true mission is giving you permanent, long-term peace of mind. That is why we include an optional upgrade to a Safety Siren Pro Series 4 digital radon monitor to function as an audible alarm, if the radon level in the home rises above The EPA action level of 4.0 pCi/L. We believe it is the best home use radon monitor available. with our standard radon mitigation system installations.
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Three other radon monitor brands I have experience with that have proven very reliable in my use over several years, are Air Things and Eco Sense and Radon Eye. All, over several years use have proved to be reliable.
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