Radon Detector for Home: What Homeowners Need to Know
A radon detector for home use can take several forms — a $15 charcoal canister mailed to a lab, a $25 alpha-track detector deployed for three months, an electret ion chamber, or a $200 to $300 consumer-grade continuous radon monitor (CRM) that talks to a smartphone app. The right device depends on whether the homeowner needs a one-time real estate decision, an annual exposure baseline, or ongoing daily tracking after mitigation. This guide walks through the device categories, what each measures, where to place it, and how Front Range geology shapes the right detector choice. This article summarizes EPA, WHO, CDPHE, and CDC guidance current as of 2026; see our methodology page for sourcing — and remember that no level of indoor radon is truly safe per the linear no-threshold model, even though regulatory action levels (4 pCi/L EPA, 2.7 pCi/L WHO) exist for response decisions.
Part of our Radon Levels guide — start there for the full picture →
What is a radon detector for home use?
A radon detector measures indoor air for radon, the naturally occurring radioactive gas produced by uranium decay in soil and rock. Detectors fall into four functional categories:
- Charcoal canisters — passive, 2 to 7 day deployment, lab analysis required, $10 to $30 per kit
- Alpha-track detectors — passive, 3 to 12 month deployment, lab analysis required, $20 to $50 per kit
- Electret ion chambers — semi-passive, used by professionals, requires reader equipment
- Continuous radon monitors (CRM) — active electronic devices, real-time reading, $150 to $300 consumer-grade, $800 to $2,500 NRPP-listed professional
For most Front Range homeowners, the choice comes down to a one-time passive test (charcoal canister for short-term, alpha-track for long-term) or a consumer-grade CRM for ongoing tracking.
Charcoal canisters — fast, cheap, single-point
A charcoal canister contains activated charcoal that absorbs radon from the air over a 2- to 7-day deployment. The homeowner places the canister in the lowest occupied level of the home under closed-house conditions, seals it after the deployment, and mails it to the certified lab listed on the kit. The lab measures radon by gamma spectroscopy of the radon daughter products in the charcoal and returns a reading.
Pricing runs $10 to $30 per kit including lab analysis. The result is a single average reading across the deployment period. Charcoal is the standard real estate transaction device when used by a NRPP-listed measurement professional running a short-term test, though most homeowners who buy one off the shelf are running it on their own.
Alpha-track detectors — long-term average
Alpha-track detectors use a small plastic film that registers a microscopic etched track each time an alpha particle from radon decay strikes it. After 3 to 12 months of deployment, the homeowner mails the detector to the lab, where the track density is counted under a microscope to derive the time-weighted average radon level over the deployment.
Pricing runs $20 to $50 per kit including lab analysis. The long-term average is more representative of annual indoor exposure than a single short-term reading because it smooths out seasonal and weather-driven fluctuation. Alpha-track is the right device for a homeowner who wants a defensible annual baseline.
Continuous radon monitors — daily tracking
Consumer-grade CRMs (Airthings View Radon, Airthings View Plus, Ecosense RadonEye, Corentium Home) sample radon hourly using either passive ionization chambers or alpha-track silicon photodiode chemistry. The device displays a rolling 24-hour average, a 7-day average, and a long-term average on its screen or in a connected smartphone app.
Strengths:
- Continuous data — see how radon varies hour by hour and day by day
- No lab fee per reading
- Long-term tracking with no recurring cost after the device purchase
- Verification that a mitigation system is performing
- Visibility into seasonal and weather-driven variation
Limitations:
- Consumer-grade CRMs are not NRPP-listed for real estate transactions — for a binding real-estate reading, a NRPP-listed professional CRM is the standard
- Calibration drift over time (most manufacturers recommend recalibration every 2 years)
- Higher upfront cost than a single passive kit ($150 to $300 vs $10 to $50)
For a Front Range homeowner who has already mitigated and wants to verify ongoing system performance, a consumer-grade CRM is the right tool. See our radon monitor feature explainer for the device-by-device breakdown.
Where to place a radon detector at home
EPA placement guidance for short-term and long-term tests:
- Lowest occupied level — basement living area, finished basement bedroom, or first floor if no occupied basement
- Breathing height — 2 to 6 feet above the floor (table or shelf height)
- At least 3 feet from exterior walls, windows, doors, and HVAC vents
- At least 12 inches from the ceiling
- Away from drafts, humidity, and direct sunlight
- Closed-house conditions during a short-term test — windows and doors closed except for normal entry and exit; HVAC operates normally
For a Front Range home with a finished basement bedroom, the basement bedroom is usually the right placement because it is the lowest occupied level and the highest-priority exposure location. The Front Range radon testing pillar covers placement specifics for Colorado homes.
Closed-house conditions for short-term tests
EPA requires closed-house conditions for short-term tests of less than 4 days. Closed-house means:
- Windows and exterior doors closed except for normal entry and exit
- HVAC operates normally — no extended fan operation, no whole-house fans
- No window fans or exhaust fans running continuously
- Conditions begin 12 hours before the test starts and continue through the test
Real estate transactions typically run a 48-hour test under closed-house conditions, which is why most Colorado contracts specify the closed-house window.
Reading the result
EPA action level: 4 pCi/L. WHO reference: 2.7 pCi/L (100 Bq/m³). U.S. indoor average: 1.3 pCi/L. Colorado statewide indoor averages: 2 to 4 pCi/L per CDPHE. Roughly half of tested Colorado homes read at or above 4 pCi/L.
Practical thresholds for a Front Range homeowner:
- Above 4 pCi/L — EPA recommends mitigation
- 2 to 4 pCi/L — EPA recommends considering mitigation (and many Colorado homeowners do)
- Below 2 pCi/L — retest every 2 years and after any major renovation
When to use each detector type
Real estate transaction
A NRPP-listed professional running a 48-hour continuous radon monitor under closed-house conditions. The CRM provides per-hour data that flags any tampering and produces a defensible reading for the negotiation.
Annual baseline as a current homeowner
Alpha-track detector deployed for 3 to 12 months in the lowest occupied level. The time-weighted average is the right number for risk extrapolation.
After mitigation verification
A short-term charcoal canister or 48-hour CRM test 30 to 90 days after the mitigation system is installed and operating. NRPP-listed mitigators usually include a post-mitigation test.
Ongoing daily tracking
Consumer-grade CRM for long-term residential monitoring. Useful in homes with mitigation systems, in homes near WHO/EPA action thresholds, and in homes where occupants want visibility into seasonal variation.
Setting up a continuous radon monitor at home
For homeowners adopting a consumer-grade CRM (Airthings, Ecosense RadonEye, Corentium Home), the setup steps are straightforward:
- Unbox the device and power it on (USB, wall outlet, or batteries depending on model).
- Pair to the manufacturer app if Wi-Fi enabled. Airthings and RadonEye both have iOS/Android apps with cloud-based history.
- Place the device in the lowest occupied level of the home — typically a finished basement bedroom or living area on the Front Range.
- Position at breathing height (2 to 6 feet above the floor), at least 3 feet from exterior walls and HVAC supply registers, and away from drafts.
- Wait 24 to 48 hours for the device to reach equilibrium and produce stable readings.
- Track the 7-day and long-term averages. Single-hour readings will fluctuate substantially — the rolling average is the actionable number.
Most consumer CRMs are designed to stay in place permanently. Battery models need occasional battery changes; USB and wall-powered models run continuously. Recalibration every 2 years is the manufacturer recommendation for most devices.
Comparing consumer CRM brands
Airthings View Radon and View Plus
Wi-Fi connected, app-driven, $200 to $300. The View Plus adds CO₂, VOC, humidity, temperature, and pressure sensors alongside radon. Long-term residential monitoring is the design intent. Multi-year cloud history is included.
Ecosense RadonEye RD200
$150 to $200. Uses a pulsed ionization chamber and produces faster equilibration than passive devices — useful results within 1 hour, stable readings within 24. On-device screen plus Bluetooth-app history.
Corentium Home (Airthings)
$170 to $220. Battery-powered, no Wi-Fi required, displays 1-day, 7-day, and long-term averages on the device screen. Simple, accurate, and well-reviewed for homeowners who want a straightforward tool without smartphone dependency.
Independent testing by university radiation programs and certified labs consistently shows all three brands tracking well against NRPP-listed professional CRMs over time. The choice between them is mostly about smartphone integration, sensor breadth (single-purpose vs multi-pollutant), and price preference.
When to call a professional
Call a NRPP-listed (National Radon Proficiency Program) measurement professional for any real estate transaction. Call a NRPP-listed mitigation contractor when any test result lands at or above the EPA action level. Call your physician about lung-cancer risk if you are a current or former smoker living with elevated indoor radon. Test on your own with a consumer-grade detector for ongoing visibility.
References
- EPA Citizen’s Guide to Radon — U.S. Environmental Protection Agency
- EPA Map of Radon Zones — U.S. Environmental Protection Agency
- CDPHE Colorado radon program — Colorado Department of Public Health and Environment
- CDC radon and health — Centers for Disease Control and Prevention
Frequently asked questions
What kind of radon detector should I buy for home use?
For a one-time read, an EPA-recognized short-term charcoal canister ($10 to $30) or alpha-track detector ($20 to $50) is appropriate. For ongoing visibility, a consumer-grade continuous radon monitor like Airthings or RadonEye ($150 to $300) is the right tool. For real estate, hire a NRPP-listed professional.
Where should I place the radon detector?
In the lowest occupied level — typically a basement living area or bedroom on the Front Range. Place it at breathing height (2 to 6 feet above the floor), at least 3 feet from exterior walls and HVAC vents, and away from drafts.
How long does the test take?
Short-term passive tests run 2 to 7 days. Long-term alpha-track tests run 3 to 12 months. Continuous monitors display readings within hours, with stable averages building over days and weeks.
Are consumer-grade radon detectors accurate enough?
Yes for homeowner monitoring. Consumer CRMs from reputable brands compare well against NRPP-listed professional monitors in independent testing. They are not certified for real-estate-binding readings — that role still belongs to NRPP-listed professional equipment — but they are accurate enough for personal use.
Front Range homeowners who want a connection to a NRPP-listed radon professional for measurement or mitigation can reach out through our contact page. Colorado’s Zone 1 baseline makes a defensible reading from a vetted professional the right foundation for any mitigation decision — and the right step before installing a multi-thousand-dollar mitigation system.
Continuous radon detectors
A digital monitor gives you an always-on reading and a long-term average — better than a one-shot kit if you want to track levels over time.
| Product | Why | Buy |
|---|---|---|
 Airthings Corentium Home | Battery, portable; trusted long-term average. | Amazon — $142.99 |
 Ecosense RadonEye RD200 | Fast first reading (~1 hr); app logging. | Amazon — $169.00 |
 Airthings View Plus | Radon + CO2 + PM + VOC in one unit. | Amazon — $329.99 |