[nate_meurer]

Those early experiments claiming that plants can clean indoor air had significant methodological problems, and the results have not been reproducible in realistic building environments:

http://www.buildingecology.com/articles/critical-review-how-...

The fact that NASA's name is associated with this study has led it to be widely accepted uncritically.

[edj]

I believe the paper they're responding to is this one: http://www.greenenergyhelps.com/wp-content/uploads/2013/04/W...