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This is a great question, and I can see where the confusion comes from. The key here is that Bosch uses the term “IAQ” to mean “Index for Air Quality”, not “Indoor Air Quality.” The IAQ (and its variant, Static IAQ) isn’t limited to indoor use; it’s simply a way of representing overall air quality based on VOCs.
As for Static IAQ (s-IAQ) vs. IAQ, here’s a breakdown:
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IAQ (dynamic IAQ) adjusts its baseline automatically over time, which makes sense for portable devices that move between environments.
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Static IAQ locks the baseline so the sensor doesn’t slowly “forget” that an environment is polluted. That’s why it’s useful for stationary devices like PurpleAir sensors, whether they’re indoors or outdoors.
So when you see “Static IAQ” on PurpleAir, it isn’t claiming to measure indoor air quality outdoors; it’s reporting Bosch’s air quality index output in a way that’s more stable and meaningful for a fixed monitor.