The 10 Best Radon Gas Test Kits

Anyone who wants a radon number without an app, a lab fee or an outlet can start with the Airthings Corentium Home. It runs on AAA batteries, so it can sit anywhere in a basement, and its screen shows a short-term and a long-term average side by side. Give it about a week before the short reading settles. Airthings now sells a Bluetooth successor, so this older model may not stay in stock for long.

The RadonEye RD200 gives a first reading in about ten minutes, because it counts radon with an ion chamber instead of a slower solid-state sensor. That speed makes it handy for watching levels jump after a rainy night or fall once a vent fan goes in. A phone app keeps an hourly history, and a small screen on top shows the current number. It has to stay plugged in, and the standard warranty lasts one year.

For a one-time check, the First Alert RD1 is a charcoal canister you leave open for two to seven days, then seal and mail to a lab. The lab fee is in the price everywhere except New Jersey, which adds a state fee, and results arrive by email a few days after the lab gets the packet. It gives a single snapshot rather than a trend, so a high result calls for a second test.

Shoppers watching their spending still get a real screen with the X-Sense XR0A-SR, which shows rolling averages for the past day, week, month and season with no phone involved. It works silently on AA batteries for about two years and keeps its stored data through a battery swap. There's no alarm, so someone has to remember to look at it, and its accuracy rests on the maker's own figures.

The Ecosense EcoBlu EB100 suits people who want a big, bright number and nothing to set up. Its ion-chamber sensor posts a first reading within minutes, and it can sound an alarm when levels run high. Daily, weekly, monthly and long-term averages sit one button press away. There's no app or saved history to export, and it needs its own power adapter, since a portable battery pack can throw off the readings.

Wave a hand in front of the Airthings Wave Radon and its ring glows green, yellow or red, while a phone app holds the actual numbers along with humidity and temperature. It runs on AA batteries for well over a year and mounts on a wall or ceiling, out of the way. There's no screen, so checking a reading means opening the app, and Airthings has stopped selling it on its own site.

Radon swings with weather and seasons, and the RSSI Alpha Track kit averages it over anything from one month to a full year. The EPA treats a long test like this as the better guide to what a household breathes year-round. Analysis and postage both ways are included, and the report comes by email or mail. It's slow by design, and RSSI won't ship it to New Jersey addresses.

Made in the U.S., according to its maker, the Safety Siren Pro4 plugs into a wall outlet and shows short- and long-term averages on a backlit screen. It checks itself once a day and offers several alarm modes, including a flashing light for people who can't hear a beep. It keeps no history and has no app, and its boxy design looks dated beside newer monitors.

When an answer can't wait, the empowerDX Express kit comes with a prepaid overnight return label, and the seller says its lab posts results the same day if the sample arrives by mid-morning. That lab is certified under the national radon proficiency program, according to the seller. It's a newer kit with few owner reports so far, and New Jersey buyers owe an extra state fee.

The AEGTEST HOUND-1011S is a rechargeable handheld monitor that can move from basement to bedroom to find where levels run highest. Its color screen shows recent averages, it beeps and flashes when a set limit is crossed, and it stores well over a year of readings. A first result takes about half a day, and its solid-state sensor and young brand have a thin accuracy record.