Japanese researcher describes (with control group) the interesting affects of walking in a forest.

https://www.youtube.com/watch?v=9jPNll1Ccn0

Indian researcher describes side affects of indoor plants on health esp. air quality.

https://www.youtube.com/watch?v=gmn7tjSNyAA

I'm incorporating some of these concepts into my tiny house design e.g. a (truly ingenious design using mirrors!) terrarium and an hinoki ofuro, together with natural daylighting.

A poster called mantesso offered up this interesting paper: Here's the original study from NASA, Interior Landscape plants for indoor air pollution abatement :

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1993007...