"The potential economic impact of indoor air pollution is quite high and is estimated in the tens of billions of dollars per year. Such impacts includes direct medical costs and lost earnings due to major illness as well as increased employee sick days and lost productivity." The health consequences of biological contamination range from uncomfortable odors to end-stage lung disease to fatality. What factors predispose to biologic contamination? Which contaminants cause adverse health effects? What illnesses are associated with which contaminants, and how do these occur? This discussion will help answer these questions, leaving the discussion of environmental sampling, interpretation of sampling results, and remediation to other speakers who presented this information. A few interesting ideas for consideration regarding the implications of biological contamination will also be presented.