Thanks @handytech. The IAQ readings seemed to remain at an abnormally high level. Maybe I just wasn't patient enough. I tested both sensors by waving around a cotton swab soaked in isopropyl and they were both still very responsive. I ended up just power cycling the sensors and clearing the stored BSEC state from the ESP32's non-volatile storage. IAQ readings seem to be back to normal. See attached graphs. Technically this was "indoor" air, although it wasn't breathable :). I guess it's just that the BSEC algorithm isn't tailored to heavily contaminated air? Or was there actually a permanent change to the resistance of the sensors?
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I have a couple BME680s, both of which were exposed to ozone in the range of 0.2ppm to 0.3ppm. One had maybe 5 hrs exposure, the other, maybe 1 hr total. This seems well below the permissible limit stated in the BME680 layout considerations document: It is not permitted to expose high concentrations of reducing (e.g. >20 mg/m 3 of TVOC) and/or oxidizing gases (>10
mg/m3 of NO x +SO x +O 3 ) to operating sensors for a long time Doing some calculations, 10mg/m3 of O3 is almost 5ppm. Please see attached graphs of static AIQ output from BSEC. "ozone (aiq)" had less exposure than "filter (aiq)". Each point on the graph is based on 20 samples taken over 60s averaged down to a single sample. The sensors shot way up and have been very slowly working their way back down. They both have been in fresh air for almost 12 hrs now. Going from memory, the raw resistance reading of the one that saw less exposure is about 20-30% higher than it previously was in fresh air. So, are these fried? If so, lesson learned 🙂 BTW, running BSEC 1.5.1474 on ESP32 via Arduino library. Polling at BSEC_SAMPLE_RATE_LP.
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