INTRODUCTION One of the most difficult problem areas relating to the degradation of air quality involves the control of chemical pollutants arising from non-stationary transportation sources. The goal for setting and attainment of national primary air standards has been set forth in the Clean Air Act of 1970. The lack of complete understanding of atmospheric interactions of a complex variety of air contaminants and physical parameters@ however@ has seriously hampered progress in achieving the desired objectives. Such difficulties are evidenced by the series of extensions and delays which have occurred in the regional implementation plans as well as in the proposed reconsideration of selected air pollutant limits. Both the federal regulatory agencies and the concerned industries are cognizant of the need for continuing improvement in the understanding of fundamental chemical and physical interactions relevant to the variations of ambient air quality. The Calspan-University of Minnesota study for the determination of the formation mechanisms and composition of photochemical aerosols represents one aspect of a broad range program jointly sponsored by the Office of Air Programs@ U@ S. Environmental Protection Agency and the Coordinating Research Council of the U@ S@ vehicle manufacturing and petroleum industries. This report presents an inter inn account of project accomplishments during the first year of program performance. The objective of the Calspan-University of Minnesota study is to elucidate the complex physical and chemical processes contributing to the production of photochemical aerosols in polluted atmospheres. Even though major advances in the knowledge of homogeneous gas phase reactions involved in the formation of photochemical smog have been gained during recent years@ the important chemical and physical characteristics governing gas to particle conversions remain largely unresolved. Laboratory experiments have invariably been confronted with physical constraints present in reaction chambers designed more specifically for investigating homogeneous 1 gas phase processes. One of the main goals of this program@ therefore@ is to establish suitable experimental facilities for simulating aerosol formation processes in the atmosphere@ The 20@800 ft3 Calspan smog chamber represents the largest photochemical reaction vessel currently available in the United States@ As part of this program@ we are systematically evaluating the performance of this chamber@ as well as the behavior of aerosols in vessels of widely different surface-to-volume ratio. Descriptions of experimental facilities design and implementation are given in Section II of this report. Experimental test systems and chamber characterization results are presented in Section III. Data analysis methodology and preliminary results are described in Section IV. At both Calspan and the University of Minnesota@ attempts have been made to characterize aerosol behavior under varying environmental conditions rather than examine aerosol formation and dynamics in highly specific reaction systems. The capability for close simulation of various atmospheric parameters within the chambers is expected to be developed during subsequent years@
API 4215-1973 history
1973API 4215-1973 DETERMINATION OF THE FORMATION MECHANISMS AND COMPOSITION OF PHOTOCHEMICAL AEROSOLS