Low-light requiring houseplants have demonstrated the potential for improving indoor air quality by removing trace organic pollutants from the air in buildings. This plant system is one of the most promising means of alleviating the sick building syndrome associated with many new, energy-efficient buildings. The plant root-soil zone appears to be the most effective area for removing volatile organic chemicals. Therefore, maximizing air exposure to the plant root-soil area should be considered when placing plants in buildings for best air filtration.
Interior Landscape Plants for Indoor Air Pollution Abatement Final Report
by NASA, John C. Stennis Space Center –B.C. Wolverton, Ph.D., Principal Investigator, Anne Johnson, M.S. and Keith Bounds, M.S. Sept. 1989.
Experiments have documented that the accumulation of particulate matter on horizontal surfaces in interiors can be reduced by as much as 20% by adding foliage plants (good news for the housekeeping staff!).
Particulate Matter Accumulation on Horizontal Surfaces in Interiors: Influence of Foliage Plants
published by Atmospheric Environment, by Virginia I. Lohr and Caroline H. Pearson-Mims. 1996, Vol. 30, No. 14,
For plants to be an effective tool in providing good indoor air quality, architects must design with plants in mind, not as an afterthought after the building is completed. There are now products available to significantly enhance the air purifying capacity of plants. In new buildings, the air can be circulated through plant filled atriums before distribution throughout the building. In existing facilities, portable devices make it possible for individuals to use plants to provide clean airin their “personal breathing zones” in office cubicles or living areas. Man’s mechanical ingenuity, in harmony with nature, can ensure a healthy environment for the 21st century.
Indoor Air Pollution – A Sixty Billion Dollar Per Year United States Health Problem. Can Houseplants Be Part of a Cost-Effective Solution? Published by Plants for Clean Air Council.
Plants and associated soil microflora can be used as effective air filters which remove and absorb toxic VOC’s from indoor air . It is possible to improve indoor air quality by using a specially screened plant combination which efficiently removes toxic compounds from ambient air.
Plants can provide an effective way of decreasing mycotoxins concentration in indoor air by destroying bacteria and fungi. Begonia and geranium were shown to decrease air microorganism content by 43%, small flowerish chrysanthemum – by 66% . In rooms where flower pots with lemons, orange-trees, tangerine-trees are located the air is almost sterile . Myrtle vulgaris – evergreen indoor plant has antibacterial action . It was shown  that volatile oils of thyme, mint, marsh tea, wormwood have fungi-static actions.
It was shown that improvement of IAQ just to the outdoor level will decrease the sick absenteeism at least by 30%  and reduce the frequency of complaints (headache, lethargy, fatigue) up to 400% and therefore increase the productivity [5,6,23,39].
Dr. N. Salansky Review,
Appendix 1, On Health Benefits of B.A.R.S