Learning Center

Plain-language explanations of the measurements, sensors and numbers behind environmental monitoring.

A single candle can push PM2.5 past outdoor smoke levels in a small room. CO₂ barely notices.

Gas hobs and ovens produce CO₂ directly. Electric cooking barely moves the number.

Each person adds a predictable amount. The curve a monitor draws is an occupancy counter.

Range is how far the instrument can read. Resolution is the smallest step it shows. Neither is accuracy.

Precision is repeatability. Accuracy is truth. A spec sheet can promise one without the other.

Every sensor slowly changes its answer to the same question. Drift is the rate, and calibration is the cure.

ABC assumes the room reaches outdoor air each week. Some rooms never do, and the baseline drifts.

CO₂ for how much fresh air a room gets; PM2.5 for what is in that air. Sometimes they conflict.

CO₂ measures ventilation. VOC indicates chemicals. Neither substitutes for the other.

Ventilation has clearly fallen behind. Not dangerous, but the room needs fresh air now.

One extra molecule per thousand, and the threshold most ventilation guidance is built around.

Outdoor air is a free 420 ppm reference. Fifteen minutes in the shade tells you if the baseline is right.