Central Campus Air Quality Model (CCAQM) Instructions

Model Output

The C4$.dat file displays all specified input data, in addition to modeled concentration data at each receptor. Listed are contributions to pollutant concentrations from each link (road) at each receptor. The column “Pred Conc” lists the predicted concentration in parts per million (ppm) at the given receptor including the ambient concentration of the pollutant. This is the value we are most interested in.

Interpretation of Data

Although the CALINE 4 model was developed for modeling CO emissions from vehicles, by assuming all of the air pollutants emitted from vehicles (CO, NO_x, HC) are conservative (non-reactive) within a relatively short time period, we can extrapolate the model to apply to all of these air pollutants. This assumption can be made because the central campus area is relatively small, these pollutants are assumed to be conservative, and they all have molecular weights on the same order of magnitude.

This does introduce slight uncertainty, since the force due to gravity acting on compounds with differing molecular weights will not be the same. However, the model assumes a settling velocity of zero, so the pollutants are assumed to be moving relatively steadily with the mean wind. This assumption is reasonable for the gases used in this module since they are relatively light. If we were to consider particulate matter, which has greater mass, this assumption would not be as reasonable since gravitational setting would occur at a significant rate.