Quantifying the IAQ scale of BME680


#1

Hi, I have been working with the bme680 for a week now and having gone through the datasheet of BME680, I don’t quite understand how the IAQ index is mapped. When we say an IAQ index 0-50, what is the exact concentration of VOC’s in the particular environment in terms of mg or ug/m^3?Can somebody please help me on this regard??


#2

It’s completely relative. The BME680 just takes a resistance reading in Ohms that is low if the air quality is low (i.e. high levels of VOCs), or high if the air quality is high (i.e. low levels of VOCs).

The way I understand it is that because each VOC is different (giving a different resistance change for a specific concentration) and any air that isn’t tightly-controlled (like laboratory conditions) will be a complex mixture of lots of different volatiles, there’s no sensible way to map a reading of say 50,000 Ohms to a specific concentration of VOCs.

Bosch’s IAQ index is completely proprietary and closed-source, as far as I know, so they don’t give any indication of how it’s calculated or what it relates to.

That doesn’t really answer your question, but hopefully helps you understand more about how the sensor works?


#3

Thank you for the reply