To get a better filtration effect you need to force air into the root zone through an active carbon layer in the soil media. That is the method used in the original nasa paper and subsequent public labs designs when trying to remove VOC's such as those emitted by printers. Active carbon adsorbs the VOC's so that the root microbes can metabolize it. Since it is a microbial filter, it becomes more effective at filtering the contaminants that it's most exposed to. Active carbon can also remove CO2, but must be recharged with lower CO2 air periodically.

The public labs design uses a aquarium bubbler to push the air, but the flows are pretty low - with retention time in my 10x12 office at 1 month. Since the VOC's are usually heavier than air, if you place the pump inlet on the floor it performs better though.

i felt a little better but honestly i think it was more placebo than anything. i didn’t have the IAQ monitor before getting the plants so i can’t know for sure what the air quality effects were.

i got 6 plants (but 1 died) and they make my living space feel more lush and comfortable, which i count as a win.

i did also eventually get a air purifier (blueair 211+) and that’s probably the main workhorse at night with the doors and windows closed (which is when i need it the most). i noticed a clear drop in allergy/asthma symptoms (sneezing, coughing, headaches sometimes) after getting the air purifier.

so a fan at the door will probably have the best bang for the buck for you, but plants are nice too. =)