In July 1997, EPA revised the National Ambient Air Quality Standard for ozone to an 8-hour average of 80 parts per billion standard. Oil exploration and production areas in California and adjacent to the Gulf Coast states will be impacted by this change, as these areas will most likely be nonattainment for the new standard.

The 1990 Clean Air Act Amendments led to many areas in the United States undertaking ozone modeling in order to fulfil the requirements for demonstrating attainment of the one-hour 120 ppb ozone standard. However, this approach, which assumes that a deterministic model can be used to predict emissions reductions that will result in no exceedance of a probabilistic standard is very questionable. Further, in reality, the requirements do not encourage agencies to explore the ramifications of different strategy options, beyond that of the attainment strategy.

Recent work suggests that the new 8-hour ozone standard may be impossible to attain for a number of areas, including the oil production area in the San Joaquin Valley. Consequently, decisions on emissions reduction strategies for these areas need to be based on considerations other than demonstrating attainment. Among these considerations are maximizing reduction of population exposure, reduction in the areal extent of ozone concentrations above the standard, and reduction of the peak.

Also, because recent studies have highlighted some real concerns with the adequacy of ozone modeling, a new approach to planning is recommended. This would utilize a process that would use both modeling and non –modeling information to develop a plan, along with an iterative review of the modeling and analysis of changes in ozone over 5 to 6 years after enactment of the plan to determine if the original strategy was on target.

In addition, the issues described for ozone modeling also are relevant for other planning requirements such as for the PM 2.5 standard and regional haze regulation. These additional problems will be highlighted at the end of this paper.

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