Development of a mathematical index that describes ozone concentration, frequency and duration

The Characterization of Ozone and Sulfur Dioxide Air Quality Data for Assessing Possible Vegetation Effects

“…The parameters proposed by Oshima 25 and Lefohn and Benedict 26 weight each of the high concentrations the same, but ignore concentrations below a defined minimum level (e.g., 0.10 ppm). The selection of the minimum level is purely subjective.…”

“…Besides focusing on hourly concentration distribution patterns and the timing of exposures as previously discussed, characterized air quality data used for biological purposes must properly weight the importance of the 1) sensitivity of the target organism at the time of exposure, 2) actual Exposure statistics summarizing air quality data that weight the higher concentrations more than the lower ones for assessing air pollution effects on crops have been suggested. For example, the 1) summation of concentrations minus a selected minimum amount, 25 2) summation of all concentrations above a minimum level, 26 3) number of occurrences for daily maximum hourly averaged concentrations greater than a minimum amount, 9 and 4) use of an exponential function 27 have been discussed as possible ways to assign unequal weighting to ozone concentrations.…”

“…8 26 from a biological perspective. To investigate the timing of episodic exposures at remote forest sites, the time of day when two or more consecutive hourly ozone concentrations equal to or greater than 0.10 ppm occurred was characterized.…”

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

“…In previous works, integrated O 3 exposure indices, proposed by Oshima 7 and modified by Lefohn and Benedict, 8 were used with agricultural crop effects data obtained from the California South Coast Air Basin, where large numbers of hourly concentrations above 0.10 ppm were frequently encountered during the growing season. The O3 exposure pat-.…”

Important Considerations for Establishing a Secondary Ozone Standard to Protect Vegetation

“…As additional evidence began to mount that higher concentrations of ozone should be given more weight than the lower concentrations, concerns about the use of a long-term average value began to be expressed. 31 " 34 In an important experiment, Hogsett et al 27 showed that alfalfa may display a greater growth reduction with a lower 7-h seasonal average concentration than with a higher 7-h seasonal average, if the former was based upon fluctuating episodic ozone exposures rather than identical daily exposures.…”