airdata.dev
Indicators
10 indicators built from this site's data: one number per place and year, so places can be compared and mapped.
visualizedata.org computes them from Yearly air quality summary by county and maps every place. Each page here says how its indicator is computed and which columns it uses.
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90th-percentile daily AQI
The AQI that only the worst tenth of days exceeded.
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Days when carbon monoxide set the AQI
The pollutant with the highest AQI that day.
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Days when coarse particles (PM10) set the AQI
Dust and other coarse particles; the pollutant with the highest AQI that day.
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Days when fine particles set the AQI
The pollutant with the highest AQI that day.
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Days when nitrogen dioxide set the AQI
Traffic and combustion; the pollutant with the highest AQI that day.
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Days when ozone set the AQI
The pollutant with the highest AQI that day.
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Days with good air
AQI 50 or below, counties with a monitor reading at least 180 days.
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Days with unhealthy air
AQI above 100, counties with a monitor reading at least 180 days.
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Median daily AQI
The middle day of the year; 0–50 is good, 51–100 moderate.
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Worst air day (highest AQI)
The single worst day; one wildfire or fireworks night can set it.