Abstract
Volatile organic compound (VOC) emissions are commonly underestimated and this underestimate is important for modeling ozone and designing ozone management. This study uses two methods to test the emissions of VOCs in the official emissions inventory for Mexico City, and evaluates the efficacy of emissions controls at reducing ozone concentrations. Ratios of total VOC/NOX and CO/NOX in morning measurements are found to be greater than these ratios in the inventory, by factors of two to three.
When applying the CIT photochemical airshed model to March 1997, the model significantly underestimates measurements of both total VOCs and of CO when using the official emissions. A best fit to the measurements is found when increasing VOC and CO emissions factors of three and two, respectively, although confidence in these corrections is low. Using these corrections, the model produces good estimates of ozone and of NOX. Modeled ozone peaks that occur early in the day are found to be sensitive to changes in VOC emissions, while later peaks are NOX-sensitive. Ozone management programs must therefore consider the timing and location of high concentrations.
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