Irritant gases and vapors are utilized in herbicides, pesticides, pharmaceuticals, household cleaners, explosives, fertilizers, refrigeration, plastics, paints, fumigants and a variety of other products. These chemicals are produced and used immediately or shipped to end-users. The potential for chemical accidents is great. A report for the Environmental Protection Agency estimated that 6,928 chemical accidents have occurred in the United States since 1980, an average of five accidents each day. As a result, 1,500 people were injured and 135 killed. More information was needed on the consequences of chemically-induced sublethal acute lung injury and on the long term outcome of chemical vapor/gas specific injury in order to differentially treat exposure to these chemicals.