Use of Episodic Controls to Reduce Frequency and Severity of Air Pollution Events

Most common urban air pollution episodes occur during readily identifiable meteorological conditions that contribute to the problem. In contrast, most air pollution controls concentrate on permanent curtailments of emissions. The argument is put forth that episodic emission control strategies can be an effective supplement to traditional measures, at a fraction of the cost. Questions regarding the legality of episodic controls have been the main barrier to their implementation. These legal issues are discussed. In addition, the forecasting and modeling implications of episodic controls are considered. Several areas have implemented episodic air pollution controls or used accurate short-term forecasts to warn the public through health advisories of pending air pollution events. Some of these success stories are highlighted. A scheme for assisting the prediction of emissions reductions based on the degree to which episodic measures are voluntary or mandatory is proposed. This method may help resolve emission reduction credit and enforcement issues, making approval of episodic measures for state implementation plans and conformity more likely. The transportation sector has the potential to make episodic measures successful. Furthermore, some of these measures are eligible for federal transportation dollars. The potential for funding transportation-related episodic controls is explored. While episodic controls cannot replace traditional controls, they can be an incremental or short-term solution that may evolve into, or be used in conjunction with, other plans. Transportation professionals are incited to develop creative short-term solutions to the pervasive, yet short-term, problem of urban air pollution.