Interesting insight. IDEA: I’m noticing that in the same area, today, there is a preponderance of high readings, because of wildfires, but also a handful of absurdly low readings. Having looked at a few, I’m guessing that’s because the outliers are mismarked as being outdoors. I propose that 1: some sort of deprecation and notification to users when their readings are consistently wildly off in the lower reading direction, from a sufficiently large number of sufficiently close meters would improve displayed data quality with a very low false positive rate. Without either the “in the lower reading direction” or “consistently” qualifiers, I’d expect a much higher false positive rate. (2: A second set of deprecations+notices with “in the higher reading direction” and “VERY consistently” qualifiers would also, I’d expect, also be useful with not quite as low a false positive rate, as a consistent point source of pollution could explain it.).
(PS I’m reviving this 9-month old topic because same area and also about false readings, and will thus notify folks I expect would likely be interested. A judgement call one could disagree with.)
PPS: It is documented in a comment today that sea salt aerosols due to high winds increase coastal particular matter readings: - Air quality on the PNW coast shows as poor, with seemingly no reason - #2 by Nalo. I suppose raindrops on a dirty surface could do the same.