Plants can combine simplicity in technology and low resource use with strong visual appeal and effectively enhance indoor air quality: help regulate temperature, remove toxins like formaldehyde and other pollutants. The use of plants to clean up the environment is called phytoremediation.
Child-safe indoor air-purifying plants – list at Inhabitots
Wikipedia list of air, formaldehyde, xylene & toluene-filtering plants
Healthy Plants at the Workplace (European Union sponsored)