Why would CO2 be caused by vaping? And surely the amount of CO2 caused by a cigarette is dwarfed by the amount exhaled by a person?
I don't know... that's maybe detectable? You'd need a pretty sensitive CO2 sensor and to be tying it to other signs to avoid "someone else walked into and out of the room"... but in principle...
I'm skeptical about this. Normal adult tidal volume is about 500mg, with a normal respiratory rate of 12/min, so 6L/min. Normal air is about 0.05% CO2, so you're at 3 grams/minute atmospherically that is inspired and expired.
We actually output closer to 4% CO2. 240ml/minute. With the windows and doors closed in my 10x20 living space and 4 people, CO2 can easily go from a baseline 4-500PPM to over 1000 in an hour. That's not 240 grams of CO2 doing that.
https://airly.org/en/the-composition-of-inhaled-and-exhaled-...
I don't know where I originally got that value from, it's one that has stuck in my head for years.
Most figures I see peg 1mL of CO2 at closer to 2mg (it's about 50% heavier than the equivalent atmospheric volume, since that's mostly N2 with some O2). Your estimate of 240 mL / minute is about 346L per day, or about 700g of CO2. That's roughly the same order of magnitude as the cited 1 kg / person / day.
edit: Another way of thinking about it: if you scale up your numbers to grams per day, you'd end up with a ludicrous 346 kg / human / day. Multiply that by 12/44 (mass of Carbon-12 vs CO2), and that's the equivalent of a human shedding 100kg of carbon every day from just breathing. Most humans don't even weigh that much.