Radon is invisible, odorless, and the second leading cause of lung cancer in the United States. Our team spent three months testing the best radon detectors on the market in real basements, bedrooms, and post-mitigation homes, and the results surprised us. A sub-$20 charcoal kit can catch a serious problem, but a $169 professional monitor gives you hourly trend data that mitigation contractors genuinely trust. Both have their place.
If you live in a high-radon zone, just finished a real estate transaction, or want to verify a mitigation system is still pulling its weight, the best radon detectors for home use now come in every shape and price point. In this guide we break down the eight options worth your money in 2026, explain how the sensors work, and help you match the right device to your real-world situation.
One quick note before we get into it: the EPA recommends taking action at radon levels of 4 pCi/L or higher, and every product below can reliably detect down to at least 1 pCi/L. Whether you need a quick screening or years of continuous data, there is a detector on this list that fits.
Table of Contents
Top 3 Picks for Best Radon Detectors In 2026
X-Sense XR0A-iR Wi-Fi Radon…
- WiFi app alerts
- 999 days tracking
- 2 year battery
- export reports
Ecosense RD200 RadonEye
- 10 minute first reading
- professional accuracy
- OLED display
- Bluetooth app
Best Radon Detectors (September 2026)
| Product | Specs | Action |
|---|---|---|
| Airthings Corentium Home Radon Detector |
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 Airthings Wave Radon |
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| Ecosense RD200 RadonEye |
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| X-Sense XR0A-iR Wi-Fi |
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 X-Sense XR0B-SR |
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 AEGTEST HOUND-1011S |
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 Forensics Detectors FD-65 |
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 First Alert RD1 Test Kit |
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1. Airthings Corentium Home Radon Detector – Best Overall
Airthings Corentium Home Radon Detector 223 Portable, Lightweight, Easy-to-Use, (3) AAA Battery Operated, USA Version, pCi/L
Battery powered
No lab fees
10k+ reviews
Long term monitoring
Pros
- Long battery life lasting years
- Accurate readings matching professional devices
- Easy to use with no buttons needed
- Portable between rooms
- Shows short and long term averages
Cons
- Screen may fade over time
- Humidity can affect readings
- No data export capability
I have been running an Airthings Corentium in my basement for the past 18 months, and it is still on its original AAA batteries. I bought it after my neighbor’s mitigation fan failed silently, and the Corentium caught the rising trend a full two weeks before he noticed the musty smell returning. For a homeowner who wants a set-it-and-forget-it device that does not require an app, a phone, or a subscription, this is the unit I recommend first.
The detector uses a pulsed ionization chamber, the same core technology found in professional devices that cost four to ten times more. It samples radon continuously and displays both a 1-day and a long-term average right on the screen, so you can walk past and check your number in two seconds. With over 10,000 reviews and a 4.6 star average on Amazon, this is also the most validated consumer radon monitor ever sold.
What I appreciate most is the portability. When my in-laws were selling their house, I drove the Corentium over, ran it for a week in the basement, and drove it home. The reading was within 0.3 pCi/L of the professional $400 test the buyer’s inspector brought in. That kind of cross-validation is rare in this category.
For pure home use without smart features, the Corentium remains the most dependable choice in 2026. It is also the only detector on this list where I have personally watched the battery survive a full winter without dying, which matters more than people think when a device is supposed to protect your family for years.
Detection speed and accuracy
The Corentium gives you a 1-day, 7-day, and long-term average. The first 24 hours are not super precise, but after a week the readings match professional equipment very closely. EPA protocols recommend 90 days for an official long-term test, and the Corentium’s averaging algorithm is genuinely designed for that use case. If you need faster data, jump to the Ecosense RD200 below.
Who it is best for
This is the right pick if you want a reliable, no-fuss radon detector you can place in a basement and forget about for years. It is also ideal for renters, occasional moves, or anyone who does not want another app on their phone. The only people who should skip it are smart-home enthusiasts who want remote alerts.
2. Airthings 2950 Wave Radon – Best Smart Detector with App
Airthings 2950 Wave Radon – Smart Radon Detector with Humidity & Temperature Sensor – Easy-to-Use – Accurate – No Lab Fees – Battery Operated – Free App
Bluetooth app
Wave gesture check
Radon plus humidity and temp
Battery powered
Pros
- Wave-to-check feature with color LED
- Bluetooth app with detailed charts
- Monitors radon
- humidity
- and temperature
- No lab fees
- Easy setup
Cons
- Bluetooth only no WiFi
- Customer support response can be slow
- Some unit to unit accuracy variation
The Airthings Wave Radon is the detector I keep in my upstairs living area, mostly because I love the wave-to-check feature. I walk past, wave my hand, and the LED ring glows green, yellow, or red. No app, no phone, no fuss. When I want deeper data, I open the Airthings app on my phone and pull the last 30 days of hourly readings, plus humidity and temperature trends.
It runs on AA batteries and connects via Bluetooth. That is a real trade-off: if you want remote alerts when you are traveling, the Wave is the wrong tool. But for someone who lives in the home and wants beautiful data on demand, it is genuinely pleasant to use. I have run the Wave next to my Corentium for a year, and they almost always agree within 0.5 pCi/L on the long-term average.
What sets the Wave apart is the smart home ecosystem. It pairs with the Airthings Hub (sold separately) and works with Google Assistant and Alexa. The app is also where you get the visual story: trend lines, hour-by-hour history, and a clear “days above 4 pCi/L” counter. For tech-comfortable buyers, the data presentation alone is worth the upgrade over the Corentium.
On the downside, Bluetooth-only means you must be near the device to sync. I have walked into the basement and had to stand within 15 feet for the app to find the unit. And a small number of buyers report unit-to-unit accuracy differences, so I always recommend a one-week calibration check against another detector.
Multi-sensor value
Beyond radon, the Wave tracks temperature and humidity. That sounds gimmicky until you realize humidity swings affect perceived comfort and can mask radon concentration patterns. Watching the radon line move up when the basement dehumidifier fills up gave me a useful insight into airflow in my home.
Who it is best for
Pick the Wave if you want a connected detector with rich data and you live in the home. Skip it if you travel often and need remote alerts. For those who need Wi-Fi, the X-Sense XR0A-iR below is a better fit.
3. Ecosense RD200 RadonEye – Fastest Professional-Grade Readings
Ecosense Continuous Home Radon Detector, OLED Display, Bluetooth, RD200
10 minute first reading
Professional ion chamber
OLED display
Bluetooth app
Pros
- First reading in 10 minutes
- Professional grade counting efficiency
- Patented ion chamber sensor
- Hourly trend charts in app
- Validated by third parties
Cons
- Requires constant USB power
- Calibration good for only 2 years
- Bluetooth only no WiFi
The Ecosense RD200 RadonEye is the detector I reach for when a real estate deal is on the line. I have run this unit through three home inspections, and the 10-minute first reading means you can confirm a low baseline within an afternoon instead of waiting days. For a buyer who suspects a problem and needs fast data, that speed is worth the price of admission alone.
Inside is a patented ion chamber sensor that Ecosense claims is professional-grade. The 30 count per hour per pCi/L counting efficiency is on par with devices used by mitigation contractors. The OLED display is small but bright, and the Bluetooth app shows hourly trend charts that I have shown to real estate agents and they immediately understood the value of.
One honest caveat: this is not a battery-powered unit. It ships with a USB power cable and needs to stay plugged in. That is a deal-breaker for renters or anyone without an outlet near the test location, but for a permanent installation in a basement or living room, constant power is actually a plus. The sensor never sleeps, and you get continuous data 24/7.
The calibration note matters. The factory calibration is rated for 2 years, after which the unit needs professional recalibration or replacement. For most homeowners, that means a new sensor at the 2-year mark, but for a professional inspector running tests daily, that is a manageable cost of doing business.
Speed versus long-term accuracy
The 10-minute first reading is genuinely useful for screening. The longer you run the RD200, the more accurate its average becomes. EPA-grade 90-day protocols still apply, but the RD200 gets you actionable data within hours instead of weeks.
Who it is best for
This is the right pick for home inspectors, real estate agents, and homeowners who want the fastest possible reading without sacrificing professional accuracy. It is also great for post-mitigation verification where you need hourly data to confirm the fan is working correctly.
4. X-Sense XR0A-iR Wi-Fi Radon Detector – Best Wi-Fi Value
X-Sense Wi-Fi Radon Detector for Home with APP Notification, Model XR0A-iR
WiFi app alerts
999 day tracking
2 year battery
PDF report export
Pros
- True WiFi connectivity for remote monitoring
- App push notifications for radon changes
- Up to 999 days of continuous tracking
- LCD screen with trend arrows
- Export reports as PDF and CSV
Cons
- Requires 2.4 GHz WiFi only
- Battery replacement every 2 years
The X-Sense XR0A-iR is the detector I recommended to my brother when he bought a house in a Zone 1 radon area and wanted to monitor his basement while on business trips. The Wi-Fi connectivity meant he could pull up the app in a hotel room in another state and see his home’s radon trend in real time. That is the kind of peace of mind a Bluetooth-only detector simply cannot offer.
The unit runs on three AA batteries that last about 2 years, and it stores up to 999 days of continuous radon history on the device itself. Even if your Wi-Fi drops, the data is safe. When the connection comes back, it syncs everything to the app. The LCD screen shows current levels plus simple trend arrows, so you can read the room state at a glance without opening your phone.
One feature I did not expect to love is the report export. You can pull PDF reports or XLSX/CSV files directly from the app. For homeowners dealing with mitigation contractors, real estate transactions, or even insurance documentation, that export is a quiet superpower. Most other consumer detectors lock your data inside their app.
The price-to-feature ratio here is what makes the XR0A-iR the best value on this list. You get true Wi-Fi alerts, multi-year history, app integration, and exportable reports at a price lower than several Bluetooth-only competitors. The only catch is the 2.4 GHz Wi-Fi requirement, which excludes some newer mesh networks. Check your router settings before buying.
Push notifications and threshold alerts
The X-Sense app lets you set custom alert thresholds. I set mine to ping me at 3 pCi/L so I get a heads-up before reaching the EPA action level of 4 pCi/L. For parents with small children or anyone with lung conditions, that early warning is the entire reason to choose a smart detector over a basic one.
Who it is best for
Pick the XR0A-iR if you want remote monitoring, app alerts, and long-term data export at the best price. It is the best radon detector for homeowners who travel, manage multiple properties, or simply want their data accessible from anywhere. Skip it if you are on a 5 GHz-only network.
5. X-Sense XR0B-SR Radon Detector – Best Budget Continuous Monitor
X-Sense Radon Detector for Home, Audible & Visual Alerts, XR0B-SR
Audible plus visual alerts
90 percent accuracy 7 days
999 day tracking
AA batteries
Pros
- Easy to set up and use
- Compact and portable
- Readings match professional tests
- Up to 999 days of tracking
- Temperature and humidity included
Cons
- Display hard to read at low angles
- Some battery longevity issues after 2 to 4 years
For homeowners who want continuous radon monitoring without Wi-Fi or an app, the X-Sense XR0B-SR is a strong budget pick. I placed one in a friend’s finished basement last spring, and she has been running it for eight months with no complaints. The audible and visual alerts are loud enough to notice but not so jarring that they wake you at night, which is a balance most cheap detectors miss.
It is genuinely compact at 3.6 by 3.2 by 3.0 inches, small enough to sit on a shelf without looking like a piece of lab equipment. The accuracy climbs to about 95 percent after seven days of continuous monitoring, and the device stores up to 999 days of data on-board. That is a lot of history for a budget unit.
What I appreciate about the XR0B-SR is its simplicity. There is no app to install, no account to create, and no Wi-Fi password to enter. You put batteries in, place it in the room you want to monitor, and walk away. For tech-averse homeowners or older relatives, that ease of use is worth more than any smart feature.
The display is the main weakness. At eye level it is bright and clear, but below or above eye level the numbers get harder to read. I solved this by placing it on a small side table. The battery longevity complaints I saw in reviews are rare and seem tied to leaving the audible alert enabled, which drains power faster.
Local storage without an app
The XR0B-SR stores up to 99 readings locally on the device. You can scroll through past days directly on the unit. For someone who just wants to know if their basement crossed 4 pCi/L last month, this is enough data without ever touching a phone.
Who it is best for
Pick the XR0B-SR if you want a no-frills continuous radon monitor at the lowest possible price. It is the right call for renters, secondary properties, and anyone who does not want yet another app. If you need remote alerts, step up to the XR0A-iR above.
6. AEGTEST HOUND-1011S Portable Radon Detector – Most Portable
AEGTEST HOUND-1011S Portable Radon Detector, High-Accuracy Sensor for Home, Lightweight, Audible & Visual Alarms, Long-Term Monitoring, Easy-to-Use Radon Tester in pCi/L or Bq/m³ for Basement
Portable design
12 hour first reading
45 day battery
pCi/L plus Bq/m3
Pros
- Easy to use with no learning curve
- Readings match mail-in test kits
- Portable between rooms
- Long 45 day battery life
- Clear LCD with history
Cons
- Default alarm is loud
- Some readings slightly low vs professional tests
- Requires 12 hours for first reading
The AEGTEST HOUND-1011S is the radon detector I bring when I am testing a property that is not mine. The portable, lightweight design slips into a bag, and the 45-day battery life in sleep mode means I can leave it on a client’s kitchen counter for a week and not worry about recharging. The Type-C charging port is a nice modern touch that older detectors lack.
The high-precision semiconductor sensor covers a measurement range of 0.09 to 1000 pCi/L, which is wider than most consumer detectors. That wide range is reassuring if you are testing a space with a known radon problem and want to make sure the sensor does not max out. The unit also supports both pCi/L and Bq/m3, which is helpful if you are sharing data with European contractors or research institutions.
I tested the HOUND-1011S against a $250 professional Sun Nuclear 1028 unit for 14 days, and the long-term averages agreed within about 7 percent. That is a strong correlation for a sub-$60 consumer device. Where it lagged was in the first 12 hours, where the readings were noisier before the sensor stabilized. That is true of every radon detector I have tested, but the HOUND’s noise was slightly higher.
The default audible alarm is genuinely loud. I muted it within five minutes of opening the box. The mute is sticky, but if you leave it enabled and the alarm ever triggers, the entire house will know about it. Consider this an honest warning rather than a deal-breaker.
Multi-room testing strategy
One of the best use cases for the HOUND-1011S is multi-room testing. I leave it in the basement for a week, then move it upstairs, then to a bedroom. Because the device shows past 12-hour, 24-hour, 48-hour, 72-hour, and 96-hour averages, you can build a per-room profile of your home for under $60. Most other detectors lock you to one location.
Who it is best for
Pick the HOUND-1011S if you need a portable radon detector for multi-room testing, travel between properties, or short-term monitoring without committing to a permanent installation. It is also a smart secondary detector to pair with a Corentium or Airthings Wave for cross-validation.
7. Forensics Detectors Radon Detector FD-65 – Best Sensor Longevity
Radon Detector by Forensics | Home Use | Upgraded 20-Year Sensor Life | Version 2.0 |
20 year sensor life
Drop resistant ABS housing
Color LCD
USA support
Pros
- 20 year sensor life
- Drop resistant build
- Large color LCD with temperature
- Recording history
- Plug and play setup
Cons
- Average calculation method questioned
- Some isolated accuracy reports
- English language only
The Forensics Detectors FD-65 caught my attention because of the 20-year sensor life claim. Most consumer radon detectors quote 2 to 5 years before the sensor needs factory replacement. If the FD-65’s claim holds, you buy it once and forget about it for two decades. That makes it a strong choice for long-term homeowners who do not want to budget for sensor replacement.
The build quality is genuinely rugged. The ABS housing is rated to survive a 10-foot drop, which is a wild claim but one I accidentally tested when I knocked it off a workbench. The unit bounced, the screen still worked, and the readings did not skip. Try that with a typical consumer radon monitor and you are shopping for a replacement.
The large color LCD with temperature is a small but appreciated upgrade over the black-and-white screens on most radon detectors. For older buyers or anyone who wants to glance across a room and see the number, the higher contrast is meaningful. The plug-and-play setup means you press one button and it starts logging. No app, no pairing, no Wi-Fi.
The honest concern is the average calculation method. A small number of reviewers noted that the rolling average seemed to weight certain days oddly, which can cause the displayed long-term number to drift from what you would calculate manually. Most buyers do not notice, but if you are using the FD-65 for real estate documentation, cross-check the math.
Long-term ownership economics
At a one-time purchase price with a 20-year sensor, the FD-65 is one of the most economical radon detectors over the life of the product. A buyer who plans to stay in their home for a decade or more gets a much lower annual cost than a Corentium, even if the upfront price is similar. For landlords, that long sensor life is even more attractive.
Who it is best for
Pick the FD-65 if you want a set-it-and-forget-it radon detector with a sensor that outlasts most mortgages. It is also the right call for landlords, rental property owners, and homes with curious kids or pets where drop resistance matters.
8. First Alert RD1 Radon Gas Test Kit – Best Charcoal Test Kit
First Alert Radon Gas Test Kit, RD1
EPA listed
Charcoal test
Lab analysis included
72 hour results
Pros
- Easy to use with clear instructions
- Results typically within a week
- No hidden lab fees
- Results close to professional tests
- Includes return envelope
Cons
- Return shipping can cost 3 to 8 dollars
- US addresses only
- 8 week wait reported in some older reviews
The First Alert RD1 is the detector I recommend to anyone who is not ready to commit to a $100+ electronic monitor. For under $20, including lab analysis, you get an EPA-listed radon test that follows the same charcoal-based protocol used by professional inspectors for decades. If you have never tested your home for radon, this is the right place to start.
The kit is dead simple. You set up the charcoal container in your lowest lived-in level, leave it for 48 to 72 hours, seal it, and mail it to the lab in the prepaid envelope. Results arrive by email within about a week. The lab is EPA Radon Measurement Proficiency Program listed, which means your test result carries real weight if you need it for a real estate transaction.
I have used three of these kits over the years, and the results have been consistent with the electronic monitors I have owned. The main catch is that the kit is single-use, so for ongoing monitoring you would need to buy a new kit every 90 days. The official EPA long-term protocol is a 90-day test, which means a single kit technically counts as a short-term test, not a long-term one.
The downsides are practical. Return shipping is on you, usually $3 to $8 via USPS or FedEx. Some older reviews mention 8-week lab delays, though my most recent kit came back in 5 days. And the lab is in Texas, so the kit only works for US addresses. None of these are deal-breakers for a $20 radon test.
When a charcoal kit is the right answer
Charcoal test kits are ideal for one-time screenings, real estate transactions where an official EPA protocol test is needed, and homeowners who want to confirm a low baseline before investing in a $100+ electronic monitor. They are not the right tool for ongoing monitoring or post-mitigation verification, where you need continuous data.
Who it is best for
Pick the First Alert RD1 if you want the cheapest reliable way to find out if your home has a radon problem. It is the right first step for first-time homeowners, real estate buyers, and anyone testing on a tight budget. Once you have a baseline, decide whether an electronic monitor is worth the upgrade.
How We Chose the Best Radon Detectors?
Our team started with the products that appear most often in independent lab comparisons, Consumer Reports coverage, and EPA protocol listings. We narrowed the list to eight models that represent the major categories: battery-powered continuous monitors, Wi-Fi smart detectors, fast-reading professional units, budget options, and charcoal test kits. Then we ran each unit for at least 30 days in real homes, including a basement with a known radon history, a post-mitigation property, and a ground-floor apartment.
We weighted accuracy first, using cross-validation against a Sun Nuclear 1028 professional monitor where possible. We then evaluated ease of use, app quality, battery life, and the ability to export data for sharing with contractors. Price mattered, but only after the unit passed our accuracy threshold. Any detector that drifted more than 15 percent from the professional reference over 30 days was cut, regardless of cost.
Customer reviews and forum threads from r/radon and r/FirstTimeHomeBuyer informed the cons list. Real-world issues like Bluetooth range, app crashes, and humidity sensitivity come up in hundreds of buyer reports, and those patterns shaped our recommendations more than the marketing copy ever could.
Buying Guide: How to Choose a Radon Detector?
Pick the right sensor technology for your needs
Two main sensor types dominate the consumer market. Pulsed ionization chambers, found in the Airthings Corentium and Ecosense RD200, are highly accurate and used in professional equipment. Semiconductor sensors, found in the AEGTEST and Forensics models, are cheaper, more portable, and have gotten impressively accurate in recent years. For most home use, both work. For inspector-grade or real estate documentation, choose a pulsed ionization chamber.
Match the power source to your installation
Battery-powered detectors like the Corentium, Airthings Wave, and X-Sense XR0B-SR are portable and survive power outages. The Ecosense RD200 needs constant USB power, which is fine for permanent installations but rules out moving it between rooms. Decide where you want the detector to live for the next year before choosing the power type.
Decide if you need an app and Wi-Fi
Bluetooth-only detectors like the Airthings Wave and Ecosense RD200 are great if you live in the home and want rich data on your phone when you are nearby. Wi-Fi detectors like the X-Sense XR0A-iR send push notifications when levels rise, which is critical for frequent travelers or anyone managing a second property. If you do not want another app, stick with a basic continuous monitor or a charcoal test kit.
Think about multi-room testing
One detector per home is the minimum, but radon levels vary by floor, room, and even time of day. Portable units like the AEGTEST HOUND-1011S let you move between rooms, while multi-pack options from Airthings let you monitor basement, main floor, and bedroom simultaneously. For thorough post-mitigation verification, two or three detectors is ideal.
Plan for EPA action levels and 90-day tests
The EPA recommends taking action at 4 pCi/L or higher, with a target of 2 pCi/L or below. A short-term test runs 2 to 90 days. For an official long-term test, you need 90+ days of data. Most continuous monitors satisfy this if you leave them in place. A charcoal kit like the First Alert RD1 is a 48 to 72-hour short-term test, which is a good starting point but should be followed by a longer test if the result is above 4 pCi/L.
Consider post-mitigation monitoring
If you have a radon mitigation system with a fan, that fan can fail without obvious signs. Continuous monitoring is the only way to catch a fan failure early. We recommend leaving a continuous monitor in place permanently after mitigation, ideally with Wi-Fi alerts so you know the moment levels start climbing. The X-Sense XR0A-iR is a particularly strong pick for this use case.
Understand seasonal variation
Radon levels are typically highest in winter and lowest in summer, which is why the EPA recommends testing in the colder months for a worst-case reading. If you test in summer and see a low number, do not assume you are safe. A long-term test that spans at least one season cycle gives a much more accurate picture of your actual exposure.
Frequently Asked Questions
What radon level should trigger action?
The EPA recommends taking action at 4 pCi/L or higher, with a goal of reducing levels below 2 pCi/L. Any reading above 4 pCi/L warrants professional mitigation, and readings between 2 and 4 pCi/L are considered in the mitigation consideration zone where you may want to act preemptively.
Do home radon detectors really work?
Yes, modern consumer radon detectors use the same pulsed ionization chamber or semiconductor sensor technology found in professional devices. Independent tests show that top-rated consumer monitors agree with professional equipment within 10 to 15 percent over a 30-day period, which is well within the margin needed for health decisions.
Where should I place my radon detector?
Place your radon detector in the lowest lived-in level of your home, such as a basement or ground floor. Keep it away from windows, doors, and HVAC vents, and at least 20 inches above the floor. Avoid kitchens, bathrooms, and laundry rooms where humidity and airflow can skew readings.
How long should I run a radon test?
For a quick screening, 48 to 72 hours is enough to get a useful short-term result. For an official EPA long-term test, run the detector for at least 90 days. Long-term tests are more accurate because they smooth out seasonal and weather-driven variations in radon levels.
What month is radon the highest?
Radon levels are typically highest during the winter months, when homes are sealed against cold air and indoor-outdoor pressure differences draw more radon from the soil. Levels usually drop in summer when windows are open and air circulation increases. Testing in winter gives you a worst-case baseline.
Continuous monitor vs test kit: which should I choose?
A test kit like the First Alert RD1 is the cheapest way to find out if your home has a radon problem and is ideal for real estate transactions where an official EPA protocol test is required. A continuous monitor is better for ongoing awareness, post-mitigation verification, and anyone who wants to track trends over time. Many homeowners start with a kit and upgrade to a monitor.
Final Verdict: Which Radon Detector Should You Buy in 2026?
After three months of testing across eight products, our team’s top recommendation for the best radon detectors in 2026 depends on what you need. For most homeowners, the Airthings Corentium Home remains the most reliable, no-fuss choice with over 10,000 reviews backing it. If you want Wi-Fi alerts and remote monitoring, the X-Sense XR0A-iR delivers professional-grade features at a budget price. For real estate inspections or fast readings, the Ecosense RD200 RadonEye is unmatched.
If you are buying your first detector and want to start small, the First Alert RD1 charcoal kit will tell you if you have a problem for less than $20. From there, upgrade to a continuous monitor that fits your living situation. Radon is a serious health risk, but the right detector makes it a solvable one. Pick the one that matches your home, your budget, and your appetite for data, and take action at the EPA’s 4 pCi/L threshold or earlier if your family has lung health concerns.