Agreed with all these observations, especially gas oven or stove usage! Our former third floor ~1200 sq ft condo would spike CO2 up well over 1400 ppm when we’d

Agreed with all these observations, especially gas oven or stove usage! Our former third floor ~1200 sq ft condo would spike CO2 up well over 1400 ppm when we’d run it, and almost instantly. Even just with two people working from home, much of the space would quickly get up to 800 or 900 ppm. I’d usually open windows as I saw it creeping up, which would quickly reduce CO2 to under 600, and then it would slowly creep up over the day.