Best smart radon monitors 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 honest 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. Below is what’s real, and what each one actually requires.

---

A reality check before you buy

Be skeptical of any “air quality monitor” sold as a radon device. Most popular Home Assistant air sensors — AirGradient One and Open Air, the Apollo MSR-2 and similar ESPHome multisensors — do not measure radon at all. They cover PM2.5, CO2, VOCs, temperature and humidity. Those are great devices for general air quality, but radon is a separate, specialized measurement and they don’t do it. If you want radon, you need a purpose-built radon detector.

---

Monitors that actually measure radon

Airthings View Plus

The Airthings View Plus 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. Set expectations on “local,” though:

• The official Airthings integration in Home Assistant is cloud-based — it pulls your data from Airthings’ servers. 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.
• The separate Airthings BLE integration reads sensors directly over Bluetooth with no cloud, but it supports the older Wave series, not the View Plus.
• Community add-ons exist that poll the device over Bluetooth and republish to your local MQTT broker, which is the most local route for the View Plus today.

So: a real radon monitor, but treat its stock Home Assistant path as cloud-dependent unless you go the community-BLE/MQTT route with a compatible Wave model.

Airthings Wave / Wave Radon

If local operation is the priority, an Airthings Wave (the radon-focused models) is the better pick because it works with the local Airthings BLE integration in Home Assistant — Bluetooth, no cloud account required for the reading. You need a Bluetooth adapter within range (a Bluetooth proxy via an ESPHome device works well for a basement unit far from your server). It measures radon plus temperature and humidity depending on model.

Ecosense RadonEye RD200

The RadonEye RD200 is a dedicated radon monitor (radon only, no CO₂/PM extras) with a fast first reading and a Bluetooth interface. It has no first-party HA integration, but two community paths work, both local over BLE: an ESPHome RadonEye sensor component read through an ESP32 Bluetooth 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: it has no Bluetooth and 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.

---

Wiring up 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.

---

Quick verdict

• Best if you want radon data and don’t mind cloud: Airthings View Plus — accurate, multi-sensor, but its stock Home Assistant integration is cloud-based.
• Best for local-only: an Airthings Wave radon model via the local Airthings BLE integration, or an Ecosense RadonEye RD200 via ESPHome / the community BLE integration.
• Wi-Fi but cloud-bound: the Ecosense EcoQube (EQ100) through a community cloud integration — convenient, but it polls Ecosense’s servers rather than running locally.
• Don’t buy for radon: general air-quality monitors (AirGradient, Apollo, Awair, Aranet). They’re good devices, but none of them measure radon.

For continuous CO2, PM2.5 and VOC monitoring alongside radon, see our best air quality sensors for Home Assistant guide.