High Resolution Characterization of Ozone Data for Sites Located in Forested Areas of the United States

Abstract

Eight years of ambient monitoring data (1978-1985) were used to characterize O₃ concentrations in eight forested areas of the United States. The analysis focused on the annual number of occurrences of hourly averaged O₃ concentrations ≥0.07, 0.08, and 0.10 ppm during the growing season (April-October) as well as during the early (April-June) and late (July-October) portions of the growing season. On the average, within those areas studied, elevated O₃ concentrations occurred more often in the Piedmont/Mountain/Ridge-Valley and Ohio River Valley areas than elsewhere. In the eastern United States, 1978, 1980, and 1983 were generally the years with the most occurrences of elevated O₃ concentrations. In these years, the later part (July-October) of the growing season experienced more elevated concentrations than the earlier part. The results presented in this analysis were used to develop recommendations for future O₃ effects research with respect to forested areas and related exposure regimes.