Recycling air

http://www.ctngreen.com/news/2009/03/ted-growing-air-recycle-indoor-air-100-with-just-3-plants/

There are many plants that I want to grow once I have my earthship, but this article explains that there are three in particular that can be used to maintain clean, healthy air: areca palm (four shoulder-height plants per person) for the living room, since it converts carbon dioxide to oxygen during the day; mother-in-law's tongue (six to eight waist-height plants per person) for the bedroom, since it converts carbon dioxide to oxygen during the night; and the money tree, which strips formaldehyde and other chemicals from the air.