Two kinds of test devices
The EPA sorts radon test devices into two groups.3
| Type | What the EPA says |
|---|---|
| Passive devices | Don’t need power. They include charcoal canisters, alpha-track detectors, charcoal liquid scintillation devices and electret ion chamber detectors. They sit in the home for a set time and are then sent to a laboratory for analysis. Short- and long-term passive devices are generally inexpensive.3 |
| Active devices | Need power. They include continuous radon monitors and continuous working level monitors, which continuously measure and record radon or its decay products in the air. Many give a report that can reveal unusual swings during the test, and some are designed to deter and detect interference. They may cost more.3 |
How long a test runs
- Every radon test should run for at least 48 hours, the EPA says.3
- Short-term tests stay in a home for 2 to 90 days. Continuous monitors are one of the device types commonly used for short-term testing.3
- Long-term tests stay for more than 90 days, and a long-term result is more likely to tell you your home’s year-round average.3
- The Health Department recommends 3 to 12 months, ideally including a heating season, because longer test periods give the most accurate measure of actual exposure.1
When a monitor is useful
- Watching levels over time. Active devices can continuously gather and periodically record radon levels and reveal unusual swings.3
- Not for a home sale. The EPA’s real estate options include a continuous monitor run for at least 48 hours, but it means a device from a qualified laboratory, with steps to prevent or detect interference.3 The Conference of Radiation Control Program Directors says consumer digital radon monitors should never be used in real estate transactions and are not for making mitigation decisions; it says to verify a monitor’s results with an approved test.4
A monitor doesn’t change the Health Department’s advice: for knowing your exposure, test for 3 to 12 months.1 The EPA says to use a radon measurement device from a qualified laboratory, and that a state or local radon official can explain the differences between devices.3 In Vermont, that’s the Radon Program at 802-863-7220 or 800-439-8550 (toll-free in Vermont) or radon@vermont.gov.1
Our pick, and why
Start with the state lab’s long-term kit. To learn your home’s typical level, the Health Department recommends a test of 3 to 12 months, ideally including a heating season,1 and its Lab lists the $25 long-term kit as the recommended test.2
A consumer digital monitor is for something else: it measures and records radon continuously while it has power, so you can watch levels change.3 CRCPD says consumer monitors should never be used in real estate transactions, are not for mitigation decisions, and should have their results checked with an approved test.4
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State lab long-term kit Our pick
Good for: knowing your home’s typical level. The Lab lists it as the recommended test.2
If you also want day-to-day readings
Three of the consumer radon monitors Airthings sells, lowest price first. Each “Shop at Airthings” link opens Airthings’ discount store, not one model’s page, so check the price there. Enter vtradon-10OFF for 10% off at checkout. Airthings ships only within the US.
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Airthings Corentium Home 2
Good for: radon (plus temperature and humidity), read on the device’s own screen with no app needed.5
Specs from Airthings
- Sensors
- Radon, temperature and relative humidity
- Screen
- LCD; after 30 days it shows 24-hour, 7-day, 30-day and long-term averages
- Power
- 2 AA batteries
- Connection
- Bluetooth, with the Airthings app
- First reading
- A 24-hour average after one full day
As listed on the Corentium Home 2 product page.5 We haven’t tested it.
$179.99 at Airthings, checked Oct 17, 2026.5
Shop at Airthings: Corentium Home 2 Affiliate link
Vermont Radon may earn a commission at no extra cost to you. How we make money
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Airthings View Radon
Good for: radon (plus temperature and humidity), with Wi-Fi and the Airthings app.6
Specs from Airthings
- Sensors
- Radon, humidity and temperature
- Screen
- 2.9-inch ePaper display
- Power
- 6 AA batteries or USB cable
- Connection
- Wi-Fi or Airthings SmartLink (with a hub); Bluetooth for setup
As listed on the View Radon product page.6 We haven’t tested it.
$219.99 at Airthings, checked Oct 17, 2026.6
Shop at Airthings: View Radon Affiliate link
Vermont Radon may earn a commission at no extra cost to you. How we make money
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Airthings View Plus
Good for: radon plus other indoor air sensors.7
Specs from Airthings
- Sensors
- Radon, particulate matter (PM2.5), carbon dioxide, VOCs, humidity, temperature and air pressure
- Screen
- 2.9-inch ePaper display
- Power
- 6 AA batteries or USB-C
- Connection
- Wi-Fi or Airthings SmartLink (with a hub); needs the free Airthings app
As listed on the View Plus product page.7 We haven’t tested it.
$329.99 at Airthings, checked Oct 17, 2026.7
Shop at Airthings: View Plus Affiliate link
Vermont Radon may earn a commission at no extra cost to you. How we make money
What we don’t claim
We don’t rank monitors or call any of them “best,” because we don’t test products. The model details above are the manufacturer’s own, from its product pages, with the price on the day we checked. For accuracy claims, read the manufacturer’s specifications. Our Airthings links are affiliate links; how we make money explains what that means.
Test your home
The Vermont Department of Health Laboratory sells radon test kits directly.1 Here’s how its kits compare with a digital monitor.
| State lab long-term kitHealth Department recommended | State lab short-term kit | Digital radon monitor | |
|---|---|---|---|
| What it measures | Radon in air2 | Radon in air2 | Radon levels, measured and recorded continuously3 |
| How long | 3 to 12 months, ideally including a heating season1 | 2 to 7 days2 | Measures continuously while it has power3 |
| Price | $252 | $502 | Varies by model; see retailer |
| Best for | Knowing your home’s typical level. The Lab lists it as the recommended test.2 | A quick answer, such as for a real estate transaction. The Health Department says to use two kits side by side.1,8 | Watching levels between lab tests. Not for real estate tests or mitigation decisions; check results with an approved test.4 It doesn’t replace the long-term test for your home’s typical level.1,4 |
| How to get it | Order from the state lab
Not an affiliate link. Or call 802-338-4736 or 800-660-9997 (toll-free in Vermont).1 | Same Lab webstore: order a short-term kit. | See Airthings monitors Affiliate link Enter vtradon-10OFF for 10% off at checkout. Airthings ships only within the US. If you buy through this link, Vermont Radon may earn a commission at no extra cost to you. How we make money |
The Lab also sells a medium-term kit (1 to 3 months, $25) and a radon in water kit for well or spring water ($25).2 Prices as listed on the Lab’s webstore when we checked; confirm when you order.
Common questions
Can a digital monitor replace a long-term test kit?
For knowing your exposure, the Health Department’s advice is a test of 3 to 12 months, because longer test periods give the most accurate measure.1 A continuous monitor measures and records radon as it runs and can show unusual swings.3
Can I use a digital monitor for a real estate test?
Usually not. The EPA’s real estate options include a continuous monitor run for at least 48 hours, but the EPA means a device from a qualified laboratory, with steps to prevent or detect interference.3 The Conference of Radiation Control Program Directors says consumer digital radon monitors should never be used in real estate transactions.4
What is the difference between active and passive radon tests?
Passive devices don’t need power and are sent to a lab after the test. Active devices need power and continuously measure and record radon or its decay products.3
How long should a radon test run?
At least 48 hours for any test, the EPA says.3 The Health Department recommends 3 to 12 months, ideally including a heating season.1
Last reviewed How we source facts
Sources
- Vermont Department of Health. Radon in Your Home. Checked 2026-10-17. ↩
- Vermont Department of Health Laboratory. Radon Test Kits (Health Department Lab webstore). Checked 2026-10-17. ↩
- U.S. Environmental Protection Agency. Home Buyer’s and Seller’s Guide to Radon (EPA 402/K-24/001, March 2024). Checked 2026-10-17. ↩
- Conference of Radiation Control Program Directors (CRCPD). Consumer Digital Radon Monitors (CRCPD guidance, reprinted in The Radon Reporter, Q4 2025, p. 39). Checked 2026-10-17. ↩
- Airthings. Corentium Home 2 (product page). Checked 2026-10-17. ↩
- Airthings. View Radon (product page). Checked 2026-10-17. ↩
- Airthings. View Plus (product page). Checked 2026-10-17. ↩
- Vermont Department of Health. Testing for Radon in Your Home (fact sheet, July 2025). Checked 2026-10-17. ↩