ABSTRACT
This chapter discusses the visibility reduction data analyzed in the last two chapters is compared to underlying causal relationships. Since institutional activity is focused on source activity, the desired model must transform the estimators in equation—which are based on physical relationships—into estimators based on source activity. Given stability in that superstructure, the conditions for the control of air quality—and hence air quality itself as an outcome—will likewise remain stable. Although analysis of the air quality data by itself indicated structural change, control for the underlying causal and institutional factors that contribute to air quality improvement and deterioration was able to explain the majority of these apparent structural shifts. Historically the institutions that have affected air quality in Southern California have experienced some dramatic changes in the rules of the game—changes comparable to a shift in the supply of and demand for air quality.
