In the South Central U.S., lower tropospheric ozone pollution continues to be a challenging problem. This paper provides an update on long-term trends analyses of the ambient ozone and precursor monitoring data collected over the past 25 years (1986-2010) in four South Central U. S. cities, following up on a previous published review of 20 year trends (M. E. Sather and K. Cavender, J. Environ. Monit., 2007, 9, 143-150). The results of these analyses should be useful to air quality scientists, managers, planners, and modelers in assessing the effectiveness of nitrogen oxides (NOx) and volatile organic compounds (VOC) pollution controls for ambient ozone concentration reduction programs. Large amounts of quantitative information for each South Central U. S. city are concisely synthesized into one graphic per city. Results reported in this paper show significant long-term decreases in ambient ozone and precursor concentrations in all four South Central U. S. cities, especially over the recent five-year period 2006-2010.
