Even in the most luxurious properties, an often-ignored issue is how the home itself can affect your health. What is a dream home without clean air? It is not rocket science to keep the air fresh. Most people know potted plants absorb carbon dioxide and emit oxygen through photosynthesis, but many are unaware that plants can also 'detox' the air. Clean air is vital to astronauts who travel long journeys in space shuttles. In the 1980s, the United States space agency Nasa started looking into ways of eliminating toxic substances. After 25 years of research, they found 50 kinds of house plants that can eliminate harmful substances. These plants do more than get rid of dust. They absorb toxic substances released from the walls and furniture, including formaldehyde, toluene, xylene, benzene and ammonia. These 'air purifiers' of nature can effectively take care of the air in your home. According to Joe Lau, a certified arborist and a member of the International Society of Arboriculture, house plants can do a much better job than green technology. 'The bacteria in the soil can decompose many substances. Harmful suspended particles in the air descend onto the leaves of plants and will reach into the soil to be decomposed,' Lau explains. Aloe vera, crab cactus, mother-in-law's tongue, kalanchoe blossfeldiana and parlor palm can absorb formaldehyde. Parlor palm also eliminates ammonia. Peace lily helps to eliminate benzene, while English ivy absorbs toluene and xylene. 'The larger the surface of the leaves, the better,' Lau adds. 'The more potted plants, the better the result. For homes with two bedrooms and a living room, you need 20 to 30 potted plants to keep the air clean.' If you think that's too many, you may want to consider switching to eco-paints. In Hong Kong, wall paints are mostly made of petrochemicals that contain volatile organic compounds (VOCs). There are more than 100 kinds of VOCs, all are toxic and the most common, formaldehyde and ammonia, can take three to 10 years to dissipate completely. 'Most people are willing to spend a great deal of money on decoration, but they seldom consider the issue of safety,' says Luk Sze-man, who owns decoration company Natural Living. 'When the toxic substances are released in the air, they can cause a variety of chronic illnesses.' The symptoms of 'Sick House Syndrome' include headache, dizziness, nausea, fatigue, irritation of the eyes and difficulty with concentration. Luk got her inspiration in Venice. The Italian city is best known for its canals and gondolas, but even though the buildings are soaked in water, the walls seem immune to mould and fungus. The Venetian secret is a natural blend of plants and minerals such as clay, finely ground marble and chalk. This special wall paint is moisture-resistant, breathable and free of toxic substances. Toxic-free household products took centre stage at ECO Expo Asia. CharcoLiving, for example, offers a cure to 'sick houses'. The solution is a charcoal-based paint called CharcoPaint, which is used as a base paint for walls and ceilings and you can use any petrochemical paint on top of it. CharcoPaint absorbs toxic chemicals from petrochemical paints and other construction materials. 'CharcoPaint contains finely ground charcoal made from Japanese red pine and bamboo, which can absorb and dissolve pollutants. They can also control humidity and stop mildew and mould from growing,' says CharcoLiving's Kwok Kin-ming.