Very inaccurate PM2.5 in SF Bay Area
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I wish the data sources (or lack thereof) were clearer.
Windy has been reporting sub-10 PM2.5 all day, nevermind that it's never that low, however, since this morning, more than 12 hours ago, PurpleAir sensors in SF showed an AQI over 200, and the whole Bay Area has and AQI of at least 150 since morning.
This is frustrating to have such inaccurate data, and no indication of how much the reported data is inferred, ultimately made up, in between reporting sensor.
https://map.purpleair.com/1/mAQI/a10/p604800/cC0#8.95/37.9987/-122.2157
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@lorenpmc Hi there, do you have any specific location in your mind? We take this data from PurpleAir, so it should be same now.
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@Ondřej-Šutera Thanks. I suspect it's still very hard to get right, the localized summarization and presentation of this complex data. I would hope for Windy to report at least 50th percentile, or preferable 90th percentile AQI averaged over a small region. I'm bothered that Windy happily reports inaccurate data, that seems reasonable on most days, but on days with poor air quality when the numbers matter most, Windy's PM2.5 numbers turn out to be terribly misleading.
I'm concerned that since Wednesday, PurpleAir has reported "PM2.5 AQI" of 200 for the entire inner Bay Area from San Jose to Berkeley to San Francisco, never (when I've checked) breaking below 120 until this afternoon, but in that same period, I have not seen a Windy-reported PM2.5 point sample above 10ug/m^3. Based on Wikipedia's AQI article these numbers are entirely incompatible, both for US AQI scales and Europe's CAQI/EAQI scales. I don't see Windy's PM2.5 reporting for locations in Berkeley, San Francisco, or San Jose correlate with data available on Purple Air. I don't see Windy reporting unhealthy AQI values here at all, when is unhelpful.
Some less testimonial evidence:
- PurpleAir history for a Berkeley sensor:
- Current mismatch, showing the consistent, erroneous PM2.5 concentration (50th/90th/95th percentile would be reasonable) reported by Windy for all of the Bay Area.
My experience using this, is like hearing: 3.6 roentgen per hour, not great, not terrible; when that is not the state of the world.
- PurpleAir history for a Berkeley sensor:
