This publication evaluates possible sources of ambient air contamination and the role of the ASU in controlling and eliminating these contaminants. The ASU contaminant evaluation includes: – identifying potential contaminants; – physical and chemical properties of the contaminants; – ASU impact on contaminants; – oxygen concentration factors; – concentration levels of contaminants remaining in oxygen; – particulates; and – conclusions/data evaluation by a third-party toxicologist and by industry.