RECEPTOR MODELING OF VOCS .2. DEVELOPMENT OF VOC CONTROL FUNCTIONS FOR AMBIENT OZONE

In this study we developed an exploratory method to investigate the po tential effect of VOC reduction from specific source categories on max imum ozone. The method is based on measurement of speciated organic co mpounds in air and application of chemical mass balance receptor model ing (CMB) to allocate ambient concentrations to specific source catego ries. This evaluation results in a sample-specific emission inventory, an estimate of the VOC emissions by source in an air mass which inclu des variations in source discharge not reflected in the conventional e mission inventory. In addition, the CMB model in conjunction with the chemical profiles for each source, provides a basis for allocating ver y reactive organic components not measured in the atmosphere but contr ibuting to O3 formation. The carbon bond reaction kinetics model (CBM- IV) is used with observed meteorological conditions and the specific s ource contributions to predict precursor conversion to ozone. Predicti ons of maximum O3 using this technique for 9 days in Chicago in the su mmer of 1987 compared favorably with measured ground-level concentrati ons determined to be downwind by trajectory analysis. Source categorie s modeled included vehicle tailpipe exhaust, gasoline vapor, petroleum refinery emissions, architectural coatings, graphic arts, vapor degre asing, dry cleaning, and waste water treatment. The end-product is a f amily of control response curves which show the relationship between c hanges in VOC precursor emissions from each source and potential maxim um ozone. The control functions for vehicle exhaust indicated that con trol of VOC from automobiles will be effective on some high O3 days bu t not on others. The method complements grid-based photochemical model s in that it will allow many more control options to be investigated t han would be possible due to computational constraints.