Climate change impact on air quality in California

California has persistent air quality problems that affect the health of millions of residents. Global climate change will affect long-term weather patterns in California with unknown consequences to air quality. This dissertation explores how climate change will influence intermediary weather patterns and how they will subsequently affect air quality in California.;The statistical relationship between the daily 1-hr maximum measured ozone concentrations and the daily maximum upper air temperature (T850) was explored for California's two most heavily polluted air basins. The temperature-ozone correlation was combined with T850 values predicted by Princeton's Geophysical Fluid Dynamics Laboratory (GFDL) model to predict how climate change will affect ozone concentrations. The results suggest that by the year 2050 California would experience an additional 22--30 days year-1 and 6--13 days year-1 with ozone concentrations ≥90 ppb under the IPCC A2 and B1 emissions scenarios (assuming emissions of criteria pollutants in California remained at 1990--2004 levels).;Output from the NCAR/DOE Parallel Climate Model (PCM) generated under the "business as usual" global emissions scenario was downscaled to regional scales using the Weather Research and Forecasting (WRF) model followed by air quality simulations using the UCD/CIT airshed model. The air quality simulations were carried out for the entire state of California with a resolution of 8 km for the years 2000--06 (present climate) and 2047--53 (future climate). Averaging predictions from over 2000 simulation days suggest that annual average PM2.5 concentrations will decrease by ∼0.6--1.9 mug m-3 in coastal and central Los Angeles and increase by ∼0.9--1.3 mug m-3 at locations within the San Joaquin Valley (SJV) and the Sacramento Valley (SACV). A corresponding analysis of the annual variability showed that the 95% confidence interval spans zero (meaning no change due to climate). Similar analysis was carried out for population-weighted annual average concentrations and average concentrations of extreme pollution events for PM0.1, PM2.5 and PM10 for California, the SACV, the SJV and the South Coast Air Basin (SoCAB). The results showed mixed responses to climate change, but in all cases the 95% confidence interval spans zero.