A project has been completed by RWDI and University of California (Riverside) to implement Dr. William (Bill) Carter's new SAPRC99 condensed chemical mechanism with explicit 1,3-butadiene and benzene chemical species into EPA's latest CMAQ release v4.3. Associated with the chemical mechanism change in CMAQ, a set of new speciation profiles was generated for the SMOKE emission processor.

A study has been conducted to apply the new SMOKE/CMAQ system to model the mobile toxic emissions and concentrations with 10% ethanol-blended gasoline (E10). E10 emissions were specifically calculated through a modified Mobile6C model, and then combined with other emissions in SMOKE. Based on the application of the new modelling system, we are able to explicitly identify concentrations of toxic species such as 1,3-butadiene, benzene, acetaldehyde, formaldehyde, along with carbon monoxide nitric oxide, nitrogen dioxide and ozone, etc. In addition, deposition rates and aerosol concentrations are also simulated with the new approach. The results will be very helpful for regional health impact studies.