BME688 IAQ

[rtalich]

Can someone explain why IAQ goes to zero with exposure to isopropanol?  I've been playing around with trying to get it calibrated... I have yet to see an IAQ status of anything higher than a one.  And I have left it on for days...  BTW, exposure to Goof Off spray causes a IAQ to go way up as expected.  Please advise.

[BSTRobin]

Hi RainerS,

1.As a raw signal, BME680 will output resistance values and its changes due to varying VOC concentrations (the higher the concentration of reducing VOCs, the lower the resistance and vice versa).metal oxide-based sensors such as BME680 can distinguish between reducing (decreasing sensor resistance) and oxidizing (increasing sensor resistance) environments.If strongly oxidizing conditions are present (e.g. chlorine cleaner, nitrous oxides from exhaust gas, higher concentrations of ozone), this may lead to wrong readout of BME since it may output “clean” air in terms of the algorithm where there is none.

2. It is necessary to confirm the composition of the Goof Off spray to analyze why IAQ is rising.

[rtalich]

Hi... not sure who RainerS is haha.  Anyway, thank you for the reply!!  

So isopropanol, according to your example, produces a strong oxidized environment?

Here is the Goof Off composition:

[BSTRobin]

Hi rtalich,

1. Could you print log to see gas resistance value when your run the code and got zero value IAQ?
2. In the days of your test, has the IAQ value always been 0?