Most people are aware of and concerned with the health effects of pesticide residues in the water they drink and the food they eat, but many are surprised to learn that pesticides are commonly found in air and rain. Scientific studies of pesticides in various atmospheric matrices (air, rain, snow, aerosols, and fog) have been ongoing for 40 years. When taken together, these studies, many of which are small and focused, provide a significant contribution to answering the questions when, where, how, and why pesticides are in the atmosphere. The studies also make an important contribution to our understanding of the environmental effects of pesticides, particularly on.