In the late '80s, NASA studied houseplants as a way to purify the air in space facilities. They found a range of plants that filter out common volatile organic compounds. In the same way, these plants can help clean the indoor air here on Earth, which is typically far more polluted than outdoor air - and not only can they remove airborne contaminants but some are also nutritious herbs for both medicinal and cooking use. Many also contain volatile oils which can be used to clean both the home and the body without the toxins of conventional products. In Air-purifying Houseplants find out how you can even prevent `sick building syndrome', and how to work with indoor plants to reduce the risk of contracting colds and other viruses, decrease blood pressure, lift the mood, reduce mental fatigue and improve sleep.