Best radon detector: the maker spec sheets sort four continuous monitors by first-reading time, averaging windows, display and power, and EPA's 4 pCi/L rule decides whether you need one at all
Maker specs compared: Airthings Corentium Home 2 shows 24h to long-term averages on 2 AA for 3 years; RadonEye RD200 reads in 10 minutes. EPA fixes at 4 pCi/L.
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OwnerSpec compares published manufacturer specifications, certification listings and sourced technical documents. Unless a page explicitly states otherwise, OwnerSpec has not laboratory-tested or used the products it compares. Editorial policy
Short answer
For a reader who will watch a radon number for months, the pick is the Airthings Corentium Home 2: Airthings’ product page lists alpha spectrometry in a passive diffusion chamber, a first 24-hour average after one full day, 24-hour, 7-day, 30-day and long-term rolling averages on an LCD, two AA batteries for up to 3 years and typical accuracy within 10%. The runner-up is the Ecosense RadonEye RD200, whose maker page prints a first reading in 10 minutes, an OLED updated every 10 minutes, a pulsed ionization chamber and a 12 V plug-in adapter. EPA’s Citizen’s Guide to Radon says to fix a home at 4 pCi/L or higher and to consider fixing between 2 and 4 pCi/L, after a follow-up test confirms the first result. Skip every monitor here if you want one answer once: a 48-hour charcoal kit is what EPA’s Step 1 describes. Skip them for a home sale too, where EPA points buyers to a tester not involved in the sale.
The picks
Wants a display with long-term averages and no outlet or app required
Airthings Corentium Home 2
Airthings page: alpha spectrometry in a passive diffusion chamber; 24-hour average after one full day; 24h, 7d, 30d and long-term rolling averages on an LCD; Bluetooth to the Airthings app; 2 AA batteries up to 3 years; typical accuracy within 10%; 5-year warranty with registration within 30 days
Wants the first number fast and has an outlet in the test room
Ecosense RadonEye RD200
Ecosense page: pulsed ionization chamber; first reading in 10 minutes; OLED updated every 10 minutes; Bluetooth app for short- and long-term trends; integrated audio alarm; 12 V plug-in adapter; coverage up to 1000 sq ft; 1-year limited warranty; page prints C-NRPP approval
Fine with app-only readings and wants the lowest-cost Airthings
Airthings Wave Radon
Airthings page: alpha spectrometry; accuracy under 10% at 5 pCi/L after 7 days and under 5% after 2 months; 0 to 500 pCi/L range; about 1.5 years on 2 AA alkaline batteries; readings and notifications in the iOS or Android app; no display
Wants radon alongside PM2.5, CO2 and VOC on one screen
Airthings View Plus
Airthings page: radon by passive diffusion chamber and alpha spectrometry, about 10% accuracy after 7 days and 5% after 2 months at 5.4 pCi/L; also PM2.5, CO2, VOCs, temperature, humidity and pressure; 6 AA batteries up to 2 years or USB-C; app shows short-term and long-term radon averages
If you are buying or selling a house this month, this is the wrong page: EPA’s Citizen’s Guide says buyers frequently want the test done by someone not involved in the sale, and no monitor below is that person.
How was this shortlist built?
Every figure here is a manufacturer-published specification read on 2026-10-03 from the page named beside it. Nothing was run, calibrated or compared against a reference instrument by this site, and every listing was confirmed in stock the same day.
Units were compared on detection method, time to a first reading, the averaging windows the device reports, display versus app, power, the accuracy statement as the maker words it, warranty and any certification printed on the maker’s page. The NRPP approved device list was read by device name; no NRSB device page was opened, so NRSB listing is not claimed for anyone.
Two candidates were dropped. The First Alert RD1 kit was not in stock on the day, and no SunRADON consumer unit returned a buyable listing. A continuous radon monitor is an instrument that counts radon decay events and reports a running concentration; a short-term kit is a sealed sampler that goes to a laboratory once.
How do the monitors compare on paper?
| Unit | Sensor | First reading | Averages reported | Display | Power | Accuracy as printed | Certification printed |
|---|---|---|---|---|---|---|---|
| Airthings Corentium Home 2 | Alpha spectrometry, passive diffusion chamber | 24-hour average after one full day | 24h, 7d, 30d, long-term | LCD, plus app | 2 AA, up to 3 years | Typical within 10% (4 days at 10 pCi/L or 7 days at 5.4 pCi/L) | None |
| Ecosense RadonEye RD200 | Pulsed ionization chamber | 10 minutes | Short- and long-term trends in app | OLED, updated every 10 minutes | 12 V plug-in adapter | Not printed in the spec table | C-NRPP (Canada) |
| Airthings Wave Radon | Alpha spectrometry | Not printed | Live readings in app | None, app only | 2 AA, about 1.5 years | Under 10% at 5 pCi/L after 7 days, under 5% after 2 months | None |
| Airthings View Plus | Alpha spectrometry, passive diffusion chamber | Not printed | Short- and long-term in app | ePaper screen, plus app | 6 AA up to 2 years, or USB-C | About 10% after 7 days, 5% after 2 months at 5.4 pCi/L | None for radon |
The NRPP list does carry Airthings and Ecosense names, but the Pro models: Corentium Pro, RadonEye Pro RD200P, EcoQube Pro. None of the four consumer units above appears under its own name.
What do EPA’s numbers mean for the reading on the screen?
EPA’s Citizen’s Guide to Radon prints two thresholds: fix your home at 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L. A picocurie per liter (pCi/L) is the unit the guide uses for radon concentration in air. The guide estimates the average indoor level at about 1.3 pCi/L and the outdoor level at about 0.4 pCi/L. What each band means is on the radon level guide.
The guide also separates short-term tests, which stay in the home for 2 to 90 days, from long-term tests, which run for more than 90 days and are more likely to show the year-round average. Its Step 1 is a short-term test; a result at 4 pCi/L or higher calls for a follow-up, and a result above 8 pCi/L calls for a second short-term test immediately.
That sequence is why a monitor’s first number is the least useful thing it shows. Airthings' own radon guidance says short-term readings swing with weather, ventilation and season, not to act on a single high or low reading, and to base decisions on the long-term average over several months.
Airthings Corentium Home 2: buy it or skip it?
Buy it if you want the averages EPA’s steps are built on, visible on the device without a phone. Airthings’ page lists a 24-hour average after one full day, then 24-hour, 7-day, 30-day and long-term rolling averages on the LCD, two AA batteries for up to 3 years, Bluetooth to the app and a 5-year warranty when registered within 30 days.
The flaw is the certification line: the page prints no NRPP or NRSB listing, and the NRPP list names only the Corentium Pro. The accuracy statement is also conditional, “typical” within 10% after 4 days at 10 pCi/L or 7 days at 5.4 pCi/L, so a low-level house waits a week for that figure.
Skip it if you want a number in the first hour: the RadonEye is the fast one.
Ecosense RadonEye RD200: buy it or skip it?
Buy it if you have an outlet in the test room and want to see the sensor respond. Ecosense’s page lists a pulsed ionization chamber, a first reading in 10 minutes, an OLED updated every 10 minutes, an integrated audio alarm, Bluetooth to an app for short- and long-term trends, coverage up to 1000 sq ft and a 12 V plug-in adapter.
The flaw is twofold. The page prints C-NRPP approval, the Canadian program, and not US NRPP, where only the RadonEye Pro RD200P is listed. And the readable spec table prints no accuracy percentage and no measurement range, so this page cannot compare it to Airthings on that line. The warranty is one year against Airthings’ five.
Skip it if the lowest lived-in level has no outlet near a sensible spot: a battery unit goes where the test belongs.
Airthings Wave Radon: buy it or skip it?
Buy it if you check your phone anyway and want the cheapest Airthings sensor. Airthings’ page lists alpha spectrometry, accuracy under 10% at 5 pCi/L after 7 days and under 5% after 2 months, a 0 to 500 pCi/L range, about 1.5 years on two AA alkaline batteries and live readings with notifications in the iOS or Android app.
The flaw is that there is no display. A visitor, a tenant or a buyer sees nothing, and the page prints no first-reading time and no certification.
Skip it if anyone in the house should be able to glance at the number: the Corentium Home 2 puts the same maker’s averages on a screen.
Airthings View Plus: buy it or skip it?
Buy it if radon is one of several things you want to watch. Airthings’ page lists radon by the same passive diffusion chamber and alpha spectrometry, about 10% accuracy after 7 days and 5% after 2 months at 5.4 pCi/L, plus PM2.5, CO2, VOCs, temperature, humidity and pressure, on six AA batteries for up to 2 years or USB-C power. The particle and CO2 side is compared on the air quality monitor page.
The flaw is that you pay for six sensors to get one. The only certification printed on the page is Calm Tech Certified, which is not a radon measurement listing.
Skip it if radon is the only question: the Corentium Home 2 answers it on two batteries instead of six.
Before you buy a monitor
Decide whether you want one answer or a running one. EPA’s Step 1 is a short-term test, and a charcoal kit such as the First Alert RD1 runs 48 hours in the lowest lived-in level, goes to a lab, and returns a result in 2 to 3 weeks, per its manual. If that single result is below 2 pCi/L and the house is not being sold, a monitor adds a long-term average and nothing else. If it is 4 pCi/L or higher, EPA wants a follow-up test, and that is the day a continuous monitor earns its place.
Who should skip a continuous monitor?
Anyone who wants one answer once. EPA’s Citizen’s Guide lists continuous monitors among the short-term devices, next to charcoal canisters and alpha track detectors. The First Alert RD1 manual describes the kit route: 48 hours in place, invalid past 96 hours, closed-house conditions for 12 hours before and during, at least 2 ft above the floor, lab receipt within 10 days. The RD1 itself was not in stock when this page was written, so no kit is linked.
Anyone in a real estate transaction. EPA’s guide says buyers frequently want tests made by someone not involved in the sale, that the state radon office can help find a qualified tester, and that two short-term tests placed four inches apart can be used to decide whether to fix. EPA’s find-a-professional page names NRPP and NRSB as the two national proficiency programs.
Anyone on a private well with a radon result in the water. That is a different measurement and a different treatment class: see uranium and radon in well water.
What goes wrong?
Acting on the first number. A 10-minute or 24-hour reading is a short-term figure. Airthings says not to act on a single reading; EPA’s guide wants a follow-up before fixing.
Testing the wrong room. EPA’s guide and the First Alert manual both place the test in the lowest lived-in level. A monitor on an upstairs shelf measures the wrong air.
Reading a certification that is not there. None of the four consumer units is on the NRPP list under its own name, and C-NRPP is Canada’s program. A monitor supports a decision to call a qualified tester; it does not replace one in a sale.
Frequently asked questions
How long does a radon detector take to give a reading?
It depends on the sensor. Ecosense's RadonEye page prints a first reading in 10 minutes and an OLED that updates every 10 minutes. Airthings' Corentium Home 2 page prints a 24-hour average after one full day. Neither first number is a decision: EPA's Citizen's Guide treats a short-term result as the prompt for a follow-up test, and Airthings tells owners to base decisions on the long-term average.
Is a continuous radon monitor as good as a lab test kit?
They answer different questions. EPA's Citizen's Guide lists continuous monitors among the devices commonly used for short-term testing, alongside charcoal canisters and alpha track detectors. A charcoal kit such as the First Alert RD1 runs 48 hours and goes to a lab, with results in 2 to 3 weeks per its manual. A monitor keeps running, which is what a long-term average over 90 days needs.
Are the Airthings and RadonEye home monitors NRPP listed?
Not under their consumer names. The NRPP approved device list read on 2026-10-03 shows the Airthings Corentium Pro, the Ecosense RadonEye Pro RD200P and EcoQube Pro, not the Corentium Home 2, Wave Radon, View Plus or RadonEye RD200. The Ecosense page prints C-NRPP approval, which is the Canadian program. The Airthings pages print no radon certification.
What radon level means I should fix the house?
EPA's Citizen's Guide says to fix your home if the radon level is 4 pCi/L or higher, and to consider fixing between 2 and 4 pCi/L. The guide estimates the average indoor level at about 1.3 pCi/L and outdoors at about 0.4 pCi/L. It also says a result of 4 pCi/L or more on a first short-term test calls for a follow-up test before fixing.
Do I need a radon monitor when buying or selling a house?
EPA's Citizen's Guide says buyers frequently want tests made by someone not involved in the home sale, and that the state radon office can help find a qualified tester. EPA's find-a-professional page names NRPP and NRSB as the two national proficiency programs. For a transaction, that route replaces a consumer monitor; buy one afterwards to watch the house over the seasons.
Fact sheet and how to cite this page
- Answer
- The pick for a months-long watch is the Airthings Corentium Home 2: a 24-hour average after one full day, 24h, 7d, 30d and long-term averages on an LCD, 2 AA batteries for up to 3 years and typical accuracy within 10%, per Airthings. The Ecosense RadonEye RD200 reads in 10 minutes on a plug-in supply. EPA’s Citizen’s Guide says fix at 4 pCi/L or higher and consider fixing between 2 and 4 pCi/L.
- Comparison basis
- Manufacturer product pages for the Airthings Corentium Home 2, Wave Radon and View Plus and the Ecosense RadonEye, compared on detection method, first-reading time, averaging windows, display, power, accuracy statement, warranty and any printed certification; the NRPP approved device list; EPA’s Citizen’s Guide to Radon for the 4 pCi/L action level, the 2 to 4 pCi/L band, short-term versus long-term tests and the follow-up test; the First Alert RD1 manual for what a short-term charcoal kit involves.
- Assumptions
- The monitor sits in the lowest lived-in level of the house, which is where EPA’s guide and the First Alert manual both place a test
- A reader buying a monitor intends to keep it running for months; a one-time answer is cheaper from a short-term kit
- NRPP and NRSB listings were checked by device name on 2026-10-03; a listing added later would not appear here
- Method
- OwnerSpec compared manufacturer-published specifications read on 2026-10-03 and confirmed each listing in stock the same day; it did not run, calibrate or cross-check any radon monitor against a reference, prints no health outcome, and reports only the figures the cited document states.
- Primary source
- EPA, A Citizen's Guide to Radon (government or regulatory source)
- Facts verified
- Last updated
- Cite as
- OwnerSpec, "Best radon detector: the maker spec sheets sort four continuous monitors by first-reading time, averaging windows, display and power, and EPA's 4 pCi/L rule decides whether you need one at all", https://ownerspec.com/air/reviews/best-radon-detector/, facts verified 3 October 2026.
Every figure above also appears, with its source, in the article. All sources ยท How OwnerSpec verifies numbers
Sources
- EPA, A Citizen's Guide to Radon (government or regulatory source)
- EPA, Find a radon test kit or measurement and mitigation professional (government or regulatory source)
- Airthings, Corentium Home 2 product page (manufacturer or vendor document)
- Airthings, Wave Radon product page (manufacturer or vendor document)
- Airthings, View Plus product page (manufacturer or vendor document)
- Airthings, radon detection guidance (manufacturer or vendor document)
- Ecosense, RadonEye product page (manufacturer or vendor document)
- NRPP, approved devices list (manufacturer or vendor document)
- First Alert, RD1 radon test kit user's manual (manufacturer or vendor document)