It could be dangerous if the room is completely sealed, as the oxygen would eventually run out.
Either way I was referring to other chemicals that plants remove from the air, not CO2.
Examples: https://www.google.com/search?hl=en-CA&authuser=0&biw=1345&b...
Depending on choice of pot and soil, most only need to be watered once a week. Even still, there are decorations that hold water to slow release for even extended times between watering. Great for vacations, or the forgetful.