Best smart radon and CO detectors for Home Assistant

Radon and carbon monoxide are two very different hazards, and the devices that detect them are different too, so this guide treats them separately. Both are life-safety sensors, which makes local control especially important: a CO alarm has to work whether or not your internet is up. Below are detectors that integrate with Home Assistant, with a note on the radio and local-control story for each. One reality check up front: most air-quality monitors do not measure radon. Radon needs a dedicated radon sensor.

For radon done fully locally, an Airthings Wave / Wave Plus / Corentium Home 2 through the local Airthings BLE integration, or an Ecosense RadonEye RD200 through ESPHome or a community BLE integration. For the most features, at the cost of full locality, the Airthings View Plus adds CO₂, PM2.5 and VOC to radon and is reached through the Airthings cloud integration, or a community MQTT bridge if you want it local. The Ecosense EcoQube (EQ100) does radon over Wi-Fi through a community cloud integration, which is convenient but polls Ecosense’s servers rather than running locally.

For carbon monoxide, the pick depends on your radio: the Heiman HS1CA-E on a local Zigbee coordinator, the Heiman C1-M for Matter (UL 2034 5th Edition, and it joins Home Assistant’s Matter integration over Thread), or the First Alert Z-Wave combo, a listed, self-sirening alarm that also reports to Z-Wave JS. For air quality that is not radon, the AirGradient ONE or Apollo AIR-1 are both fully local. Do not buy a general air-quality monitor (AirGradient, Apollo, Awair, Aranet) for radon; they’re good devices, but none of them measure radon.

Be realistic: the set of radon and CO devices with local HA support is small. Keep certified, self-sirening alarms as the primary life-safety layer, and use Home Assistant for the smart layer on top. I haven’t run any of the detectors on this page; every pick rests on the maker’s documentation, the Home Assistant integration docs, and what other users report.

Radon detectors that work with Home Assistant

Radon is a colorless, odorless radioactive gas that seeps up from soil and can build to harmful levels in basements and lower floors. It’s the second-leading cause of lung cancer after smoking. A continuous radon monitor won’t replace a proper short-term test kit for real-estate disclosure, but it tells you how levels move day to day - after rain, when the HVAC runs, when you crack a window - which is exactly the kind of trend data that’s useful in Home Assistant.

The catch with radon and local-first: very few continuous consumer radon monitors are designed to run entirely on your own network. Radon sensing is niche and most of the products that do it are tied to a manufacturer cloud. There’s no Zigbee or Z-Wave consumer radon detector worth recommending; the established options are Bluetooth (BLE) monitors that you bring into Home Assistant locally. Below is what’s real, and what each one requires.

Airthings (Wave radon models, Corentium Home 2, and the View Plus)

Airthings makes the most popular consumer radon monitors. Which Home Assistant path you get depends heavily on the model, so don’t assume “Airthings” means “local”:

• The local Airthings BLE integration reads the device directly over Bluetooth (a Bluetooth adapter or an ESPHome Bluetooth proxy within range, which works well for a basement unit far from your server), with no cloud account. But it does not cover every Airthings model: the supported list is Wave (gen 1), Wave Radon, Wave Mini, Wave Plus, Wave Enhance, and the radon-focused Corentium Home 2. The Wave radon models measure radon plus temperature and humidity depending on model; the Wave Plus measures radon plus CO₂, VOC, temperature, humidity, and pressure. The Corentium Home 2 is Airthings’ current radon-focused unit and also reports temperature and humidity. If local operation is the priority, these are the better pick.
• The View Plus (and the other View-series displays) is the most common smart radon monitor people pair with Home Assistant, and it does measure radon along with CO2, PM2.5, VOCs, humidity, temperature and pressure. But it is not supported by the Airthings BLE integration. Its radon reading comes through the Airthings cloud integration (which uses Airthings’ servers and an account), or via a community add-on that polls the device over Bluetooth and republishes to your local MQTT broker. As of recent Home Assistant releases the cloud integration has, at times, omitted the radon and pressure entities, so check the current state before relying on it. If you want a View Plus to be fully local in HA, the community MQTT bridge is currently the route - there is no first-party local option.

Radon updates are slow by nature (hourly-ish), which is normal for the measurement.

Ecosense RadonEye (RD200)

The Ecosense RadonEye RD200 is a dedicated radon monitor (radon only, no CO₂/PM extras) with a fast first reading and BLE output. It has no first-party HA integration, but two solid local paths exist, both over Bluetooth: the ESPHome radon_eye_ble / radon_eye_rd200 sensor component (read it via an ESP32 BLE proxy), or a HACS custom integration (the rd200v2 project, with variants for V1 and V2 serial ranges). Heads-up: the Ecosense phone app holds an exclusive Bluetooth connection while open, so force-close it on every phone in range or Home Assistant can’t read the device.

Ecosense EcoQube (EQ100)

The EcoQube is Ecosense’s Wi-Fi radon monitor (2.4 GHz only). Unlike the RD200, it is cloud-bound, not local: its Bluetooth is used only for the initial Wi-Fi setup, not for reading data, and it exposes no local API. The way into Home Assistant is a community cloud integration (e.g. hass-ecosense-radon) that polls Ecosense’s servers every few minutes for the current radon level. It’s a fine monitor, but treat it as a cloud device - there’s no local-only path today.

What does NOT measure radon

This trips a lot of people up. Be skeptical of any “air quality monitor” sold as a radon device:

• AirGradient ONE / Open Air are excellent local air-quality monitors (PM, CO₂, VOC, NOₓ, temp/humidity) with an official Works-with-Home-Assistant integration - but they do not measure radon.
• Apollo AIR-1 and Apollo MSR-2 are ESPHome Wi-Fi sensors (air quality and mmWave presence respectively). Neither measures radon, and neither is Z-Wave or Zigbee - they’re local ESPHome devices. The MSR-2 in particular is mainly a presence and light sensor that also reports temperature and pressure, and it measures CO2 only if you add the optional sensor, with no PM2.5, VOC or humidity reading at all.
• Awair and Aranet monitors don’t measure radon either.

If you want radon, you need an Airthings or RadonEye-class dedicated radon monitor. The air-quality sensors above are great companions, just not radon detectors. For the full field of those companions, see the Home Assistant air quality sensor roundup.

Wiring up radon alerts in Home Assistant

However you get the reading in, the automation side is the same. Radon is reported in becquerels per cubic meter (Bq/m³) in most of the world or picocuries per liter (pCi/L) in the US - 1 pCi/L is about 37 Bq/m³. The US EPA action level is 4 pCi/L (~148 Bq/m³); the WHO suggests a lower reference of 100 Bq/m³.

A sensible automation: trigger a notification when the multi-day average crosses your chosen threshold rather than on a single spike, since radon readings are noisy hour to hour. Many people pair a high reading with turning on a fan or HVAC circulation and watching whether the trend drops.

For a fully local data path, point the device at a local MQTT broker (Mosquitto) where possible, and keep the dashboard and alerting on your Home Assistant instance so nothing depends on internet access. BLE range matters: place the monitor within Bluetooth range of your HA host or an ESPHome BLE proxy, or readings won’t come through.

CO detectors with smart integration

For smoke specifically (rather than carbon monoxide), see my companion guide to the best smart smoke detectors with local alerts.

For carbon monoxide the local-first choices are Zigbee, Z-Wave, and now Matter over Thread; all three keep the alert on your own network.

Heiman CO detector (Zigbee, Z-Wave, or Matter)

Heiman sells its carbon monoxide sensor in more than one radio, and the model suffix is what tells you which: the HS1CA-E (and the older COSensor-EF-3.0) is Zigbee 3.0, the HS1CA-Z is a Z-Wave Plus variant with S2 security and its own 85 dB sounder - the commonly listed HS1CA-Z is the 868.4 MHz European model, so check the frequency for your region - and the C1-M is Matter over Thread, certified to UL 2034. The Heiman Smart Carbon Monoxide Alarm in my catalog is that Matter model; it needs a Thread border router rather than a Zigbee coordinator. Match the suffix to the network you already run; the three will not join each other’s network. The Zigbee model pairs to a local Zigbee coordinator and is fully supported in Zigbee2MQTT - exposing a carbon_monoxide binary state plus battery - and partially supported in ZHA. Heiman also joined the Works with Home Assistant program in February 2026, bringing certified devices into the program. This is the most straightforward way to get CO status into HA locally so you can trigger lights, sirens, or shut off a gas appliance, all without the cloud.

First Alert / Kidde Z-Wave smoke + CO combos

If you’re on Z-Wave, First Alert’s Z-Wave Plus combination smoke and CO alarm (the ZCOMBO line, and its newer SMCO410 replacement) is a listed, self-sirening alarm that also reports to a Z-Wave controller. It joins Z-Wave JS in Home Assistant and exposes smoke and CO states, though some of the extra entities take a little interpretation. Because it’s a certified standalone alarm with its own 85 dB siren, it doubles as the primary life-safety device - a nice property a bare Zigbee sensor doesn’t have. (Note: First Alert and Kidde are separate brands; the widely used Z-Wave combo here is First Alert’s.)

A note on hubs/coordinators

To use a Zigbee CO detector you need a Zigbee coordinator (a USB stick like Home Assistant Connect ZBT-2, Sonoff/SMLIGHT dongles, or a ConBee III - which is a Zigbee coordinator, with Thread firmware available, not a Z-Wave hub). For Z-Wave devices you’d use a Z-Wave controller (e.g. a Z-Wave stick with Z-Wave JS, or a RAZberry board). The Matter model needs neither of those - it needs a Thread border router. Some hardware is one on its own (a HomePod mini or second-generation HomePod, a Thread-capable Apple TV 4K, a Nest Hub 2nd gen or Google TV Streamer), while a Home Assistant radio such as the Connect ZBT-2 becomes one only after you install the OpenThread Border Router add-on - and it runs Zigbee or Thread, not both at once, so it cannot be your Zigbee coordinator and your border router at the same time. Don’t mix these up: match the coordinator to the device’s radio.

Safety caveat

Treat networked CO sensors as a supplement to, not a replacement for, certified standalone CO alarms with their own local siren. Many jurisdictions require listed CO alarms, and you never want your only CO warning to depend on Home Assistant being up. A Zigbee Heiman detector gives you HA integration; keep a listed standalone CO alarm as the primary life-safety device.