AqiSeverityColors

Semantic palette for the six EPA AQI categories, following StatusColors' per-theme pattern.

EPA publishes canonical category hex values (#00E400 Good … #7E0023 Hazardous), but those are billboard colors and several are unusable as text: #FFFF00 Moderate scores 1.01:1 against our light surface. So EPA's hue order (green → yellow → orange → red → purple → maroon) is preserved while each category is re-toned per theme — dark tones for light surfaces, light tones for dark surfaces. AqiSeverityColorsTest pins every tone at WCAG AA text contrast (4.5:1) against both surface and surfaceVariant (the metric-log card background).

Color is never the only signal: the category name is always rendered next to the AQI value.