On Affecting the Long-Term Air Quality in the San Francisco Bay Area

The long-term air quality objectives in the San Francisco Bay Area strive to return the quality of air to 1940 conditions as a best condition but under no circumstances to permit the quality of air to deteriorate below 1970 conditions. Although some improvement in air quality is to be expected over the next decade because of stricter automobile pollution controls, it is expected that the pressure of a rapidly increasing population will tend to overwhelm these otherwise encouraging improvements. Using a simple homogeneous mixing model of the San Francisco air basin as an illustration, a maximum pollution-level constraint on each of several pollutants is derived using the air quality standards of the State of California. In view of the fact that pollution derived from transportation is considered to be the major source function, an analytic model is developed whereby state or federal decision makers can tradeoff various transportation options in order to meet the demand of an ever increasing commuting public while at the same time staying within a given pollution-level constraint. Although the approach presented is developed using derived data assuming a simple homogeneous mixing model and specifically addresses the transportation problem, the tradeoff approach is easily generalized to accepting data derived from more sophisticated models as they become available as well as extended to other sources of pollution suich as power plants and industrial systems.