Air quality
Plain guides to official alerts: what the levels mean, who issues them, and where to find the original. Official warnings and local authorities always come first.
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Air quality
What the AQI numbers and colors mean
The US Air Quality Index runs from 0 to 500 in six colors. What each level means, PM2.5 vs. ozone, who counts as sensitive, and what Action Days are.
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Wildfires · Air quality
Wildfire maps: where official fire data comes from
Fire maps mix perimeters, satellite hotspots and incident reports. Where each comes from (NIFC, InciWeb, NASA FIRMS, state agencies) and how to read them.