Unit of measurement for VOC seems to be wrong with current Home Assistant

[jmerifjKriwe]

What happened?

Seems that the unit of measurement for VOC shouldn't be 'ppb' if you use the current version of Home Assistant (2023.1).

What did you expect to happen?

According to https://www.home-assistant.io/integrations/sensor/ it's only allowed to be:

volatile_organic_compounds: Concentration of volatile organic compounds in µg/m³

How to reproduce it (minimal and precise)

Use any sensor with voc, e.g. Xiaomi VOCKQJK11LM

will result in:
Entity sensor.mysensor_voc (<class 'homeassistant.components.mqtt.sensor.MqttSensor'>) is using native unit of measurement 'ppb' which is not a valid unit for the device class ('volatile_organic_compounds') it is using; Please update your configuration if your entity is manually configured, otherwise create a bug report at https://github.com/home-assistant/core/issues?q=is%3Aopen+is%3Aissue+label%3A%22integration%3A+mqtt%22

Zigbee2MQTT version

1.29.1 commit: 7d67ffc

Adapter firmware version

20221102

Adapter

zStack3x0

Debug log

No response

[sjorge]

ppb -> µg/m3 is not an easy conversion as you need to know stuff about the exact gas mix it is detecting.

I gave up when adding support for https://www.develcoproducts.com/products/sensors-and-alarms/air-quality-sensor/, it also reports ppb and it even has a table but none of the formulas I found even came close to the table they listed.

I imagine it would be similar for the Xiaomi one, this conversion will also be device dependent so one that works for one might not even be close for another device.

[dreimer1986]

New Beta 2023.2.0B0 now shows this Warning:

Entity sensor.co2sensor_voc (<class 'homeassistant.components.mqtt.sensor.MqttSensor'>) is using native unit of measurement 'ppb' which is not a valid unit for the device class ('volatile_organic_compounds') it is using; Please update your configuration if your entity is manually configured, otherwise create a bug report at https://github.com/home-assistant/core/issues?q=is%3Aopen+is%3Aissue+label%3A%22integration%3A+mqtt%22

If it is not convertible, maybe the better idea would be to talk to the HA authors?

[IvovanWilligen]

If it is not convertible, maybe the better idea would be to talk to the HA authors?

Is second this solution :)

[Koenkk]

Pushed a fix for this, device_class will be removed now if unit_of_measurement != ug/m3.

Changes will be available in the dev branch in a few hours from now. (https://www.zigbee2mqtt.io/advanced/more/switch-to-dev-branch.html)

[satter]

I switched my VOCKQJK11LM sensor to display VOC in mg/m3 on screen and compared it with ppb value reported via zigbee

ppb	mg/m3	coef ppb-> μg/m3
312	0.71	2.28
306	0.7	2.29
300	0.69	2.30
218	0.5	2.29
1304	2.99	2.29
2111	4.84	2.29
126	0.29	2.30
108	0.25	2.31
92	0.21	2.28
79	0.18	2.28
56	0.13	2.32
49	0.11	2.24
42	0.1	2.38
35	0.09	2.57
19	0.04	2.11
33	0.08	2.42
84	0.19	2.26
92	0.21	2.28
69	0.15	2.17

On average coefficient is 2.3, on lower values variance is greater
I will try to record more data with different temperatures, but 2.3 is looks fine for me to convert ppb -> μg/m3