This project aims to understand the similarities and difference in the air quality between South Florida (SoFl) and Southern California (SoCal), two coastal, urban areas with distinct geography, meteorology and industry characteristics. The focus of investigation will be on ground-level ozone and particulate matter (aerosol), two air pollutants of most widespread health concerns. Ozone levels and aerosol mass concentrations in each area for the past decade will be obtained from government agencies such as Environmental Protection Agency and California Air Resources Board. Time series and multivariate statistical analyses will be performed to understand the evolving trends of these pollutants, as well as identify the main factor(s) controlling ozone and aerosol formation. These results can potentially help improve pollution forecast abilities and formulate more effective control strategies, especially for aerosols where uncertainties persist. Further, PM10 and PM2.5 aerosol samples will be collected under various atmospheric conditions. These samples will be subjected to multiple analytical methods for composition analysis and structure elucidation, especially mineral dust, black carbon and organic carbon. Past research suggests that the composition of atmospheric aerosols is very complicated with only partial understanding, rendering it difficult to fully assess their health and climate impacts. The results here can potentially bridge the gap in this issue. In addition, the comparison between PM10 and PM2.5 sample analyses shall yield useful information on the origins and atmospheric processes of aerosols. Overall, such a comparative study can reveal how different infrastructures and natural conditions, coupled with specific control measures, affect regional air quality as well as offer insights on more effective control strategies.