Buying Guides

Research-based buying guides that compare the leading options by documented specifications, real use cases and value.

One person, a closed door and a laptop: 1,000 ppm within the hour. A monitor across the room and a rule about the door fix it.

Place it away from the pillow, read the morning peak, then adjust the door and window until it stays under 1,500.

Continuous power, honest export, calibration you control, and memory or cloud that will not lose the data.

Portable for surveys, travel and one monitor across many rooms; fixed for a permanent record in one place.

Two thresholds, a delay, a quiet night mode, and one alert that reaches the person who can open a window.

Bluetooth for battery life and privacy; Wi-Fi for remote alerts and long logs. Decide by where you will read it.

Get the CSV out, get it into a spreadsheet, and read the four shapes that matter.

Two measurements from one chart: the plateau tells you fresh air per person; the decay tells you air changes per hour.

Put every spec on the same footing: fixed plus percentage, at the same ppm, under the same conditions.

Breathing height, interior wall, a meter from people, away from vents and windows. Room-by-room placements.

Read the listing, look for the module, then do the sanitizer test. Three checks before you trust a number.

Check the monitor, check the placement, read the trend, then apply the bands. A four-step routine.