Proposal for an Air Pollution Alert System for the South Coast Air Basin

Abstract

The purpose of this proposal is to provide a meaningful alert plan for the South Coast Air Basin that could also be useful in other basins. The key element of the proposal is the calling of a significant number (10-20 per year) of alerts on the days when air pollution levels are predicted to be most severe. During these alerts, definite and enforceable restrictions on use of motor vehicles would be in effect to sharply reduce and/or eliminate pollution from this source. In addition, alert conditions would restrict certain types of industrial and commercial activity. Finally, better health warning information would be provided to allow the most sensitive fraction of the population to avoid exposure to conditions cannot tolerate. We begin the discussion defining measures of pollution severity based on both the average level and exposure time as a basis for deciding on what measures should be taken. The specific control measures are suggested based on the current distribution of the emissions from various sources. They would limit the emissions of the sources with the highest emission factors first, but progressively tighten the control as the severity of the pollution increases. A procedure for predicting when alerts will occur is described. This procedure will minimize the disruption involved in calling an alert by taking advantage of the natural diurnal cycle of human activities in the basin. It also recognizes that there is a time lag in the build-up of secondary pollutants (oxidant and NO_2) and that emissions of primary pollutants (hydrocarbons and NOx) must be restricted before the atmospheric reaction takes place. Finally, we give estimates of how often different levels of alert would typically be called, based on the suggested levels. The use of alerts as an incentive to adopt low emissions technology and/or adopt activities that reduce the per capita pollution, such as car pooling, will also be discussed.

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