The cheaper sensors detect volatile organic compounds, and assume that CO2 level correlates with that. This isn't necessarily true. BigClive tested one, and cal

The cheaper sensors detect volatile organic compounds, and assume that CO2 level correlates with that. This isn't necessarily true. BigClive tested one, and called it a party detector[0], because it was great at picking up alcohol, but not so good at detecting when a literal stream of CO2 was blasted at it. [0] https://www.youtube.com/watch?v=D2Wq4Yg52No https://www.youtube.com/watch?v=D2Wq4Yg52No