Abstract View
Sensitivity of Inorganic PM2.5 to Present and Future Emission Changes and Implications for Reduced Complexity Models
CARLOS HERNANDEZ, Sonal Nayak, Spyros Pandis, Peter Adams, Carnegie Mellon University
Abstract Number: 411
Working Group: Health-Related Aerosols
Abstract
Reduced complexity models (RCMs) generally produce PM2.5 health damages by marginally perturbing precursor emissions, and then quantifying the downwind impacts on human mortality. However, marginal health damages may be used for impact analyses where policies result in non-marginal emission changes, or for future policy scenarios where emission baselines differ from those used to develop RCMs. In both cases, present-day marginal health damages may not capture potential changes to PM2.5 sensitivity. In this work, we explore changes in the sensitivity of inorganic PM2.5 resulting from large perturbations and future changes to the emission baseline. Simulations from the PM-CAMx chemical transport model are used to develop health damages resulting from a 25% emission reduction from present and future case baselines in the continental U.S. Present case emissions are derived from the 2008 National Emissions Inventory. Future case emissions are estimated by scaling present case emissions uniformly to correspond with 2057 emission totals under the RCP 4.5 scenario. Month-long simulations for January and July are used to account for seasonal differences in emissions and chemistry. Simulations outputs are used to estimate seasonal and annual nationwide health damages for inorganic PM2.5. Emissions for NH3, NOx, and SO2 change by +25%, -66% and -83%, respectively, between the present and future cases. Health damages for NH3 decrease by 83% across both months, while changes for NOx and SO2 are modest. Health damages for NOx increase by 100% and decrease by 30% for January and July, respectively, due to the seasonally varying role NOx plays in regulating the oxidant pool. We find that RCM health damages are largely robust, however analysts should practice caution when evaluating scenarios with changes to NH3, or where seasonal differences are of concern. Future work will consider the role of changing demographics and wealth on health damages.