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.