When? When the indicators tell you that the CO2 is high. CO2 monitor is also used in industrial processes where ventilation is difficult and equipment is heavy. The monitor tells you when to leave the area.

Your question is irrelevant. The article wants to address climate change, not indoors: "This breakthrough addresses a critical need in environmental monitoring: accurately understanding "how much" CO2 is being emitted to combat climate change and global warming."

The breakthrough will help with X, Y, and Z. You might have a problem with x, but Y and z are also important.

Still you think it's my mistake that I didn't side track the original conversation.

The point to establish is the device is useful for many reasons and that is the spirit of HN.

Looks like you still don't get it. The article had zero intentions to talk about indoors, and you think it's my fault, because you asked "You do realize that indoor air quality is also a thing, right?" Whatever the spirit of HN is, it would be rude to dismiss my comment just because I talked specifically about the claim of the article, which is global warming in general. If you want to talk about indoors, do it in a different thread, and stop bullshitting me. You have only been inappropriate and rude to me.