Watching CO2 in isolation tells you what CO2 is doing. Watching CO2, VOC, NOx, PM2.5, humidity, and temperature together tells you what's happening. The dashboard's real interpretation layer is a small library of co-movement fingerprints.
Gas-stove cooking: NOx and PM2.5 rise together within seconds of ignition. VOCs follow within 1-2 minutes. Humidity rises gently from water vapor. CO2 rises if the kitchen is closed. Hood-on flattens NOx and PM dramatically; hood-off leaves all four elevated for the duration. Recovery: 30-60 minutes after cooking ends.
Bedroom overnight: CO2 climbs slowly and monotonically. RH climbs slowly too. PM stays flat. VOCs and NOx stay flat. The shape is distinctive: a near-linear ramp lasting 6-8 hours, ending in a sharp drop when the door opens.
Candles or incense: PM2.5 spikes sharply with mild VOC accompaniment. NOx stays flat (combustion is too cool for nitrogen fixation). CO2 barely moves. Cleaning products: sharp VOC spike, everything else flat. Wildfire smoke event: PM2.5 elevated for hours, mild VOC tail, NOx mildly elevated, CO2 flat, outdoor PM correlated.
When the dashboard tells you "looks like dinner," it isn't reading the time of day, it's reading the fingerprint. When it tells you "looks like wildfire smoke," it cross-checks against the outdoor PM feed. When the pattern doesn't match anything in the catalog, it shows the parameters and says so honestly. This article enumerates the catalog; the next decade of product development will refine and extend it.
