Air pollution contains complex toxins causing diverse central nervous system (CNS) pathology through several interrelated mechanisms that may lead to CNS disease or other degenerative diseases. This chapter describes that the clinical effects of air pollution are legion. It categorizes these areas in distinct anatomical physiological areas of the body. The chapter explains them as follows: nasal, neurological, respiratory, cardiovascular, reproductive, immune, genitourinary, and gastrointestinal systems. There is much overlap and therefore at times the lines will be hazy just as the clinician sees the individual patient. The toxic odors can rapidly mask and chemically sensitive patients stay too long and will become ill for hours to days because the toxic odors are masked with weakness, fatigue, and cloudy brain becoming nonfunctional. The genetic basis of odorant-specific variations in human olfactory thresholds, and in particular of enhanced odorant sensitivity, remains largely unknown.