The dashboard shows sunrise, sunset, solar noon, and moon phase alongside the air-quality data. The pairing is not decorative. Several air-quality parameters have strong diurnal patterns governed by the solar cycle, and several human responses to air quality (sleep, alertness, exercise) are governed by the same.
Outdoor ozone is the canonical example: it is photochemically produced and peaks in the mid- to late afternoon on sunny days, dropping to near-zero overnight. The "open a window" suggestion respects this; opening at sunrise on a forecast-high-ozone day is meaningfully different from opening at 3 PM. The NOAA solar calculator provides the time-of-day baseline; the dashboard caches your local solar schedule.
Indoor patterns mirror occupancy. CO2 follows breathing density, which follows the sleep-wake cycle. Cooking pulses cluster around meal times. Cleaning happens in characteristic windows (weekend mornings for many households, evenings for others). The AI learns the household's circadian rhythm over a few weeks and uses it as a strong prior: an unusual signal at an unusual time gets weighted differently than the same signal during its usual window.
Human circadian biology brings its own air-quality dependencies. Lux exposure during the day sets the circadian clock (see lux); insufficient daytime light is the most common circadian-rhythm disruptor in office workers. UV index pairs with lux for outdoor decisions (see UV index). The ambient-context widget gives users one place to see all of these together, which is how air-quality decisions actually get made: in the context of "what time is it and what is the sun doing right now?"
References
- WHO - Circadian rhythms and health www.who.int
- IES - The Lighting Handbook www.ies.org
- NOAA Global Monitoring - Solar position calculator gml.noaa.gov
- EPA - Ground-level ozone basics www.epa.gov
