Fun fact: humans do not have oxygen levels detection, but do have CO2 levels detection. Your body would ring all kinds of the alarm bells if CO2 levels rise above the norm, even if there is enough oxygen.
Its not that I'm afraid to die here :) Its more about improving the quality of the air. And the body is pretty bad at recognizing higher than norm CO2 level unless it gets to life threatening levels. ( https://youtu.be/1Nh_vxpycEA?t=45 )
At night plants start to produce CO2 as well - when you're sleeping and most vulnerable! If the amount of CO2 they scrub is significant, the amount of CO2 they produce in the evening should be as well, no?
Plants produce a net deficit of CO2, so you're correct but over a 24 hour period with proper lighting they will produce more oxygen than CO2. The important thing, however, is that they produce this CO2 at night at such an unbelievably slow rate that you wont be choking to death in your sleep, that's silly. If you fill a room with plants and cut out the lights, most CO2 produced will be from your cat sleeping on the floor than from the plants.
Either way I was referring to other chemicals that plants remove from the air, not CO2.
Apparently plants put out half the CO2 again over the night that they took in. I'm just thinking that either way they aren't that big of deal as far as oxygen/carbon dioxide production/consumption. Air filtration, possibly.
I didnt really mean CO2 specifically, I meant it improves air quality by removing other chemicals from the air. Either way the effect is not completely insignificant especially over long periods of time with correct conditions.