Today's home and office buildings have become so energy efficient that very little outdoor air circulation occurs within their walls at any time of the year. Windows in many newer structures cannot be opened at all. Although that is not the case in most residences, homeowners have been extremely diligent about installing airtight windows and doors in houses to cut down on energy costs. Residents opt for the highest-rated insulation package to keep out drafts and maximize the savings in the operation of heating and cooling systems. While that's great for the environment, the result is that homes and offices harbor trapped pollutants and chemicals that can make you ill. Over the last thirty years, the indoor environment has become much more sealed off and filled with synthetic materials that leach chemicals called VOCs—volatile organic compounds. Recognizing which of the many possible VOCs are in the air is a daunting task; VOCs are in every manufactured substance, from caulking to computers.

Among the most notorious culprits are benzene, trichloroethylene (TCE), and formaldehyde, which are found in common products in industrial and household settings. Benzene is a solvent present in numerous items, such as inks, oils, paints, plastics, rubber, gasoline, detergents, pharmaceuticals, and dyes, as well as explosives. This substance has been known to irritate skin and eyes. Acute inhalation of benzene causes dizziness, nausea, headaches, respiratory diseases, liver and kidney damage, irregular heartbeat, and lymphatic system diseases. External contact with skin may cause dermatitis, drying, patchiness, swelling, inflammation, and blistering.

Dry cleaning services overwhelmingly use TCE, which can also be found in paints, lacquers, adhesives, inks, and varnishes. Repeated exposure to TCE contributes to toxic air quality and might lead to a high incidence of carcinomas and liver damage.

Most indoor environments have considerable levels of formaldehyde, commonly found in the particle board or pressed wood products that manufacturers use in office furniture, shelving, and foam insulation. The most publicized form of this substance is urea-formaldehyde, whose resins appear in many paper products, grocery bags, facial tissues, paper towels, and cleaning products. Side effects of prolonged exposure to formaldehyde include headaches; irritation of the mucous membranes of the eyes, nose, throat; contact dermatitis; and asthmatic conditions. Some readers may have worked in structures that were tested and diagnosed with "Sick Building Syndrome" after significant numbers of employees became ill and missed work. This diagnosis calls for remedial action to restore indoor air to a healthy state.

To combat the escalating effects of exposure to these chemicals and to raise air quality levels in our indoor spaces, environmental experts recommend the use of plants that mitigate the toxicity. In most buildings identified with sick symptoms, management employs office plant services to strategically place a variety of toxin-absorbing plants in the workplace. Likewise, homeowners who suspect high levels of impure air can hire environmental firms to test the air quality and take action to rid the home of pollutants. Common indoor plants are one of the most effective ways of combating the stagnant, unhealthy air that lingers in our environment. For detailed information about studies that address clean air and the use of plants, contact NASA, the Associated Landscape Contractors of America, and/or the National Cancer Institute.

Live Trees and Plants for Health and Beauty
If your goal is to purify your indoor environment's air and maintain healthy humidity levels, the following passages highlight tips for growing a selection of houseplants that reduce indoor air pollution and absorb harmful gases. Plants will also produce negative ions—much as air purifying machines do—and will effectively remove dust particles, mold spores, and bacteria.

For best air-cleansing results, place two or three plants in each average-size room; add another plant or two for larger rooms. Cluster plants in bigger rooms according to specified growing conditions for maximum benefit. Horticultural experts recommend having fifteen to twenty plants strategically located in a two-thousand-square-foot home. Be sure to find a space for at least one live plant in each sleeping area. You'll find that these plants help to eliminate formaldehyde, benzene, carbon monoxide, TCE, and most toxins that lurk in building and household materials.

Gerbera Daisies will grow indoors and out. They love the sunshine and come in bright, cheerful shades of red, yellow, orange, and pink. Deadhead their spent blossoms, keep the soil moist but well-drained, and fill a sunny corner with these beauties. Mature clumps are the best bloomers and give you the option to move your plants outdoors next spring to fill your deck boxes with amazing color.

Weeping Fig, also known as Ficus, is a tree with shiny leaves that needs bright light and adequate space. Ficus grows best in an established location, doesn't like to be moved, requires less water in winter, and actually prefers the pot-bound state. If the air is too dry, leaves turn yellow and drop. Feed quarterly.

Bamboo Palm and Butterfly Palm are medium-to-large plants that look like trees, especially the bamboo variety, which can grow over 5 feet tall. Its canopy-like growth is especially attractive when used to fill a corner. Realtors often use them strategically in sale properties to attract buyers. They like light, but not direct sunshine. The bamboo variety requires little watering, but if brown leaves appear, you haven't watered enough. The graceful butterfly palm has a fountain-like form and needs evenly moistened soil. Mist it with water, keep it clear of drafts, and clean the leaves to keep it dust-free. An excellent air purifier, butterfly palm removes formaldehyde and xylene from the atmosphere.

Golden Pothos is a cascading plant that looks attractive on a shelf or ledge. This plant does well in all but direct sunlight and needs watering only when the soil becomes dry. Some gardeners place this plant at the base of a tall indoor tree, such as corn plant, a member of the Dracaena family. Pothos are very robust and last a long time with proper care.

Jade plants remind me of little trees. They have thick, fleshy leaves on thick, fleshy stems with clusters of small white flowers; over time they may grow a massive trunk. Jade prefers moderate light levels. Placing this houseplant in an east-facing or west-facing window or within 2 to 3 feet of a south-facing window gives it the required three to five hours of bright, direct sunlight each day. If the stems become spindly, your plant doesn’t get enough light.

Dracaena plants, good for reducing all toxins, are African in origin and come in many varieties and sizes. Some Dracaena, such as the Marginata, Variegated, and Janet Craig resemble small trees, reaching a height of approximately 5 feet. Characteristics vary in that Marginata (also referred to as "tri-color") has creamy white stripes edged in red; Janet Craig has dark-green lance leaves banded in white or yellow; and Variegated has long, 24-inch leaves with a green center stripe. These plants love good light and evenly moist soil, but they don’t tolerate water on the leaves, which causes spotting. Dracena are excellent decorative plants that grow best in large pots. They add dramatic accents to your tabletop, desk, or favorite niche.

Houseplants are especially beneficial in winter, when they emit water vapor and help to maintain humidity levels. Environmental horticulturists also favor Boston Fern, Peace Lilies, Schefflera, and Snake Plant to purify your space. Test your healthy green thumb and discover how plants make a difference in the air you breathe.

From Llewellyn's 2012 Moon Sign Book. For current-year calendars, datebooks, and almanacs, click here.