Indirect Source Impact Analysis-Carbon Monoxide Modeling

This paper reviews current methods and models used in estimating the impacts of indirect sources on CO air quality, an important process in rapidly growing areas. The paper gives an overview of the modeling process, reviews how to obtain fleet average emission factors, presents a commonly used set of worst-case meteorology, identifies dispersion models available for predicting local CO concentrations and tells how to predict an 8-hour average CO concentration given a 1-hour prediction. The paper also discusses background CO concentrations and some of the issues involved in choosing reasonable receptor locations. Several problems exist with indirect source impact analysis—in both the technical area and the policy area. Increased effort is needed to correct these problems, especially to quantify the probability of the worst-case meteorology and to define the locations of reasonable receptors.