Much less expensive than other treatments, try getting a dozen or two of artificial ficus trees. 5' and 8' as leafy as you can find. I have purchased a lot of artificial ficus from At Home stores. The 5' trees are only $40. The 8' are more expensive, but I can't remember their price.
They are very effective diffusers and have improved every room where I've heard them used.
They are very effective diffusers and have improved every room where I've heard them used.