WASTE REDUCTION -- Waste is the ultimate externality or pollution produced by humans and all other living organisms. In the past, humans have dealt with waste primarily by simply discarding it upon the land. As the world becomes increasingly urbanized, however, waste that is simply thrown away upon the land becomes a primary cause of disease and water pollution. Also, landfills generate methane, a gas that contributes more to global warming than carbon dioxide. Also, we have to use carbon fuels to transport garbage to more and more distant landfill locations from our urban cities. Finally, the more technologically advanced we become as a society, the greater percentage of our wastes that come from chemicals and thus are hazardous wastes. All of this requires a new concept where we need to learn to design our built environment in ways that eliminate waste (or that starts to look at what were traditionally wastes as renewable resources). Because of tough pollution control laws in developed nations, many companies are already doing this with their wastes. But we need to do a better job of waste reduction where we incorporate this as a "sustainability" criterion in everything we do.