AccUnni’s CO2 Monitor is a straightforward tool for a specific job: telling you when the air in a room is stale. It measures carbon dioxide, which is a direct indicator of ventilation. High CO2 means you’re breathing in what others just exhaled, and that leads to fatigue and poor concentration.

The device gives you a clear, immediate readout. A large digital screen shows CO2 levels in PPM, alongside temperature and humidity. It uses a simple three-color LED system—green, yellow, red—so you can gauge air quality at a glance. An audible alarm will sound if levels become genuinely poor. The fold-out stand and compact size let you place it on a desk or shelf without fuss.

It’s a simple monitor, not a data logger. You won’t get graphs or app connectivity. For checking if your home office or classroom needs a window opened, however, it provides exactly the actionable feedback you need.