Comparison Between Key Species Simulated Using the Simplified Indoor Air Chemistry Simulator (SIACS) and Previously Published Values from Reference Models Nicole

People spend approximately 90% of their time within indoor environments, and consequently, characterizing the chemistry of indoor air is valuable from a human health perspective. A simple-to-run indoor air chemistry model is needed as an initial screening tool for public health applications. The Simplified Indoor Air Chemistry Simulator (SIACS), which is currently in development by EPA, incorporates 78 chemical species with 211 chemical reactions and aims to fit this need. The concentrations of key species simulated using SIACS were compared to previously published values from the Indoor Chemistry and Exposure Model (ICEM) by Sarwar et al. (2002) and the mathematical model by Nazaroff and Cass (1986). Preliminary results from SIACS for the steady state OH concentration for the base case scenario was within −36% of ICEM. Furthermore, we observed good agreement between SIACS and the predicted values by Nazaroff and Cass for some of the key species (PAN, HONO, HCHO, RCHO, and NO2) for the base case scenario. Conversely, agreement between models was the poorest for OH and HO2. With regards to the perturbed scenarios, preliminary results showed better agreement between models for OH in all perturbed scenarios compared to the base case.