The dashboard uses a small vocabulary of words with specific meanings. Knowing them removes ambiguity from what the AI is telling you. Baseline is the rolling 24-hour median for each parameter in your space; it adapts to your normal but ignores brief excursions. The VOC index uses a slightly different 24-hour baseline (Sensirion's algorithm) but the concept is the same.
Elevated means above the 75th percentile of your last-30-days distribution for that parameter, or above an absolute health threshold (whichever is higher). It's a soft signal: the air is busier than normal, but nothing immediate is required. Spike means a change of more than 2 standard deviations from the rolling mean within 5 minutes: a real event, not a sensor jitter, with a definite onset.
Trend means a sustained directional movement (rising or falling) for 6+ hours: the slow CO2 climb overnight is a trend; a 10-minute VOC spike is not. Trends are what bedroom CO2, off-gassing furniture, and mold-risk humidity show. Anomaly means the pattern doesn't match anything in the co-movement catalog the AI knows: PM elevated without VOC, or NOx rising with no CO2 change. Anomalies get logged but not interpreted; they're what the AI flags as "I see this, I don't know what caused it."
A few other terms. Tier refers to the EPA AQI color band the IAQ score currently occupies. Fingerprint is the multi-parameter signature of a known scenario (cooking, sleeping, cleaning). Cross-reference means the dashboard checked the value against the outdoor feed. Confidence when the AI gives an interpretation, indicates how well the signals match its expectations. Low confidence does not mean wrong, it means worth a second look.
References
- EPA - AirNow: AQI Basics www.airnow.gov
- Sensirion - SEN66 datasheet and VOC index info sensirion.com
- Sensirion - NOx index info note sensirion.com
- WHO Global Air Quality Guidelines (2021) www.who.int
