Add unit conversion for radon measurement

The HA Airthings integration and ESPHome AirThings BLE integration both currently pull in radon data in units of becquerels per cubic meter, or Bq/m³. In the US, radon is typically measured and evaluated in units of picocuries per liter, or pCi/L. While it’s easy enough to create a template sensor and divide Bq/m³ by 37 to get pCi/L, it would be great if units of radon could be changed via the UI just as other units can be changed as of 2022.4.

2nd this also… just hooked up my airthings view radon… it took a couple hours for the sensor to show up only to see it is 18.0 Bq/m³ instead of in pCi/L measurements. A helper would be great for this.

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Did anything ever come of this? Just set this up today and I still don’t see a way to change it to pCi/L.

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Agreed, still trying to figure the best way to convert this

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I managed to get it to work. My 1st template. Replace your entity name and drop this in Configuration.yaml.


  • sensor:
    • name: “Airthings Base - Current Radon (US)”
      unit_of_measurement: “pCi/L”
      state_class: measurement
      state: “{{ (states(‘sensor.BLAH_radon’) | float / 37) | round(2) }}”