What sensor, exactly, are you describing here? Different VOC sensors have different gas sensibilities, as well as different algorithms to interpret the gas sensor raw data.
replyHigh pass or low pass? Many instruments have a low pass filter. Very few have a high pass filter.
replyHigh pass. Probably actually band pass.
replyThe instrument is pretty crappy - it has basically no calibration or, AIUI, long term stability. So you can’t really use it to characterize the chemical content of the air. What you can do is observe changes. I’m guessing the manufacturer wanted to avoid people getting confused by the absurd raw reasons, so they came up with a formula called “VOC Index” that HPFs the data. It will average 100 IIRC. You’re supposed to use it to notice events that cause changes - if it hits 170 every day at 2 PM them you can guess that something’s happening at 2 PM.
None of this is in the chip. It’s implemented by the driver. There’s an implementation in esphome, for example.