This text looks at the physical and chemical properties of particulate matter, including the use of various microscopic techniques. It then describes the effects that these particles have on the biology and health of humans, particularly on the effects studied in the lungs. The book describes how particulate matter is monitored, looks at the ways to decrease particles in the air, and includes discussions of government policy and legislation. Particle toxicology studies have undergone significant changes since 1995, and this book captures the current picture.