A number on a screen, and what it does and does not tell you
These devices report a number, and the number is only as good as the sensor behind it. A genuine NDIR CO2 sensor and a cheaper estimated-CO2 sensor can both show a reading on the same size screen, and only the manufacturer's specification sheet says which is fitted. We compare which pollutants are actually sensed — CO2, PM2.5 particulates, VOCs, humidity and temperature are different sensors, not one chip that does everything — the stated accuracy and calibration method, whether logging happens on-device or requires an app and account, and battery life against mains dependency. These pages report what a monitor measures and how the maker says it should be read; they do not turn a reading into a health verdict, which is the business of public health guidance, not a comparison site.
0–3000 ppm CO2 · LED traffic-light · USB powered
A pocket-sized, USB-powered CO2 display with a three-colour LED traffic light (green/yellow/red) and an alternating CO2/temperature readout. No app, no Bluetooth, no battery to replace — just a plug-in monitor for a single room.
Best for: A single room where someone wants a plain go/no-go ventilation cue — a bedroom, home office, or classroom — without setting up an app.
≈ 35 €
NDIR sensor · ±50 ppm accuracy · Bluetooth + app
A Bluetooth CO2, temperature, and humidity monitor built around a Swiss-made NDIR sensor, refreshing readings every second with a claimed ±50 ppm accuracy. The large display works standalone; alarms, app notifications, and the full 6-in-1 screen need a separate SwitchBot Hub 2.
Best for: Someone who wants a stated NDIR accuracy figure and is willing to add a SwitchBot Hub 2 later for app alerts and automation.
≈ 50 €
CO2 + PM2.5/PM10 · NDIR + laser sensor · rechargeable
A handheld multi-pollutant monitor combining an NDIR CO2 sensor with a laser particle sensor for PM2.5 and PM10, alongside temperature and humidity. Readings show on a colour TFT screen, with an audio alarm and CSV export over USB — no Wi-Fi or companion app.
Best for: Anyone who wants CO2 and particulate readings together in one portable unit, and is comfortable exporting data manually rather than watching it in an app.
≈ 160 €
7 sensors incl. radon & CO2 · Wi-Fi + app · battery powered
A seven-sensor Wi-Fi monitor covering radon, PM2.5, CO2, VOCs, humidity, temperature and air pressure, read through the Airthings app. Radon is sampled with a passive diffusion chamber and alpha-spectrometry detection; the unit runs on AA batteries or USB and can act as a hub for other Airthings devices.
Best for: Whole-home air monitoring where someone wants radon and VOC coverage alongside CO2 and particulates, and is comfortable running everything through the Airthings app.
≈ 230 €
The number and type of sensors decide what the device actually sees. A device with only one sensor says nothing about the rest.
A simple device is enough to discover a home's variations and to know when to ventilate.
It varies a lot: particles, carbon dioxide, volatile organic compounds, temperature and humidity. Not every displayed value comes from a dedicated sensor.
It is the most directly usable indicator: it rises in an occupied closed room and falls when you ventilate. It tells you when to open up.
Domestic sensors give orders of magnitude and trends. It is the change that matters, not the absolute value.
Some sensors recalibrate automatically in outdoor air. The instructions say whether the device needs taking outside periodically.
In the living area, at breathing height, away from an open window and a heat source. A device near a vent measures the outside.
No, never. Carbon monoxide is a lethal hazard that demands a dedicated certified detector, not a comfort indicator.
Continuous measurement is more informative than a spot reading. Trends over the day reveal when to ventilate.
An air quality monitor is never a carbon monoxide detector: the latter is a certified safety device, entirely separate. Carbon dioxide is the most usable indicator — it tells you when to ventilate — and it is the trend that counts, not the absolute value.
Only the specifications at least four models out of five state. A column that is more empty than full compares nothing.
| Model | Price | Amazon reference |
|---|---|---|
| TFA Dostmann AIRCO2NTROL MINI | 35 € | B00TH3OW4Q (identical on DE/FR/IT/ES) |
| SwitchBot Meter Pro CO2 | 50 € | B0DBVDWB6G (identical on DE/FR/IT/ES) |
| Temtop M2000C 2nd | 160 € | B08X279P7V (identical on DE/FR/IT/ES) |
| Airthings View Plus | 230 € | B097YW5Q72 (identical on DE/FR/IT/ES/US/GB) |
Specifications: manufacturer sheets and Amazon product pages. Prices and availability: Keepa. No product on this site has been physically tested.
Most recent revision in this category: August 24, 2026.
Prices quoted in these summaries are dated readings. The live price is shown next to each product.
