Green paint claims to improve indoor air quality, or IAQ, but exactly what defines high IAQ? That depends on who you ask. There are a number of public and private organizations, from the EPA to the US Green Building Council, that address IAQ in their standards. But it seems everyone's concerned about IAQ these days, including Oprah! If you don't want to get down into the data, the EPA's site is probably the best for those of us living in existing houses or apartments. They suggest three basic strategies to get cleaner air in your home.
Control the source. Don't use harsh chemicals, such as paint stripper inside. Do not smoke or let friends smoke in your home. Keep pets clean. Vacuum often, and use a vacuum with a HEPA filter especially if your home may have lead paint. Run range hoods when cooking.
Ventilate and dilute. Open windows. Consider installing an air-to-air heat exchanger if you live in a climate where the heat or AC is usually running.