I had the opportunity to help a family improve their home by finishing their basement some time ago. It was a fairly simple project: take a completely unfinished basement and build a bedroom, bathroom, closet, and large family room. There were a few other neat features, but overall a very straight forward project. There was one catch though. One of their children was extremely allergic and chemically sensitive, which made the materials we used extremely important. Hours of research made it possible to use materials that were safe for the whole family. But those hours of research also showed me the importance of what materials are used while building and remodeling for everyone.
Are you aware that most common finishes used in homes emit VOCs, or volatile organic compounds? According to the US EPA's website, "Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors." Some VOCs are linked to cancer in both animals and humans. Other side affects can include hyper-activity in children, loss of concentration, headache, nervous system damage, irritability, breathing difficulties, and many others. Not much is currently known about the long-term affect of continual exposure. (http://www.epa.gov/iaq/voc.html)
What are some sources of VOCs in your home? Carpet, paint, wood finishes, cabinets, countertops, many adhesives, window coverings, and many home furnishings. Also included are many common household cleaners and chemicals, such as printer ink. That is not an exhaustive list. You may think throwing up your hands and saying "Nothing I can do about it!" is the only option, but that's not the case. VOCs can dissipate over time, so airing out your home as much as possible can help a great deal. Switching your cleaning supplies to natural alternatives such as vinegar can also be beneficial. Whenever you purchase a new piece of furniture, allow it to sit in a ventilated space like a garage for a few weeks. Allow your dry-cleaning to air out before wearing it. These day-to-day changes can help improve your indoor air quality substantially.
If you're building or remodeling your home, you'll have to communicate your desire to use non-toxic and/or natural materials with your contractor. Some contractors will be more able to accomodate you than others. Some non-toxic materials are roughly the same price as conventionally used ones, while others can be more expensive. Generally speaking, on a major remodeling project like finishing a large basement you'll see an increase of 10% or less. If you want to go for more unconventional "green" alternatives, you can pay substantially more.
Remember, your home is where you spend a lot of your time. If you're planning on doing any work to it, make sure you're aware of what is being used. While function and appearance are the parts you'll appreciate most from day to day, the knowledge that you've included materials that won't actively poison you and your family will provide peace of mind for years to come.