The way emission rates vary over time is an important factor in the design of any air pollution control strategy, including emissions trading. This chapter examines how the emissions trading program handles the temporal dimension. Of particular concern are the fluctuations in pollutant concentrations that occur from one period to the next. How are fluctuations in ambient concentration integrated into the goals pursued by the emissions trading policy and the procedures used to achieve those goals? Are the procedures cost effective? Can the temporal component of the current policy be improved?
Pollutant concentrations at specific receptor locations are monitored by taking samples of the air at frequent, regular intervals. Typical plots of concentration frequencies recorded from those samples show the ambient concentration to be distributed as a log-normal random variable.1 The log-normal distribution is nonsymmetric, with the modal (most frequent) concentration lower than the mean (average). One example of a distribution fitting this description is given as figure 9.____________________