Pollution

http://www.elephantjournal.com/2009/03/clean-fresh-air-with-these-three-common-houseplants-kamal-meattle/

http://www.ted.com/talks/kamal_meattle_on_how_to_grow_your_own_fresh_air.html

http://lifehacker.com/#!5149643/three-plants-that-give-you-better-indoor-air

place cornmeal around an antheap. Ants eats the cornmeal but can't digest it, killing the colony

air quality
http://www.ceroi.net/reports/pretoria/issues/air_qual/overview.htm

http://www.saaqis.org.za/