A statistically tested short term oxidant control strategy

Abstract

A possible short term oxidant control strategy would involve: 1. (i) reduction of overall reactive hydrocarbon and NO x emissions, 2. (ii) restriction of morning commuter traffic 3. (iii) a shift of emissions into the evening and night time photochemically inactive hours. Since these represent the emissions alterations which usually mark the change from weekdays to weekends, the actual effects of such a strategy can be evaluated in advance from statistical studies of past weekday-weekend differences in monitored oxidant levels. As a test, we have used data from the South Coast Air Basin in the Los Angeles area. Results presented earlier have shown that switching to a weekend emissions pattern on random days would be counterproductive, i.e. oxidant levels would on the average increase. In this paper we demonstrate that there exists a definable subset of conditions under which switching to weekend emissions would significantly decrease average oxidant levels both one and two days into the future. Fortunately, this strategy works best just when it is most needed, under conditions of particularly adverse oxidant levels.