The other issue with plants is that having them in any decent numbers means you’re likely to have at least some with a mold/fungus/pollen issue, so they actuall

The other issue with plants is that having them in any decent numbers means you’re likely to have at least some with a mold/fungus/pollen issue, so they actually reduce air quality. Outdoors that’s not so much of an issue because there’s airflow and the mold/fungus/pollen is dispersed, while inside your room it’s limited to a very small amount of still air.