ABSTRACT
This chapter discusses basic properties of airborne contaminants, including shape, density, size, concentration, source, and microbiological composition. In this book, particulate contaminants primarily refer to solid particles larger than 0.01
m
m in diameter, and thus include smoke and fumes. Gaseous molecules, though very small particles, have very different characteristics and behavior from particulate matter. These characteristics will be discussed in more detail in Chapter 5. In the last section of this chapter, threshold limit values (TLVs) for typical indoor air contaminants are discussed. These TLVs will serve as the criteria for many indoor environment qualities and therefore are presented early in this book.
