Analysis of atmospheric ozone concentration trends by eighth highest values

In Taiwan, the ambient air quality standard of ozone is 0.12 ppm, which is not to be exceeded by the observed hourly ozone concentration to protect human health. For each day, the maximum hourly ozone concentration is to be identified. For an entire year, the eighth highest value of the 365 daily hourly maxima is used to test the compliance of the standard. To account for the uncertainty in measurement, the regulation stipulates the three-year moving average of the eighth highest value is the figure for use in comparison with the standard. This research collated the observed ambient hourly ozone data from 1998-2002 at 9 continuous monitoring stations maintained by the Government. The eighth highest concentration (MAX8) was calculated for each site by year. For the estimate of confidence interval for MAX8, this research applied a linear regression of the ozone concentrations on their ranks, and a quadratic logistic regression of odd ratios on ozone concentration. To estimate the confidence interval by using the quadratic *Corresponding author. Tel.: 886-4-23323000 ext. 4451; Fax: 886-4-23742365; E-mail address: hhyang@cyut.edu.tw