Meteorologically-dependent trends in urban ozone

✍ Scribed by Li-Shan Huang; Richard L. Smith

• Book ID: 101277789
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 201 KB
• Volume: 10
• Category: Article
• ISSN: 1180-4009
• DOI: 10.1002/(sici)1099-095x(199901/02)10:1<103::aid-env341>3.0.co;2-d

✦ Synopsis

Ozone concentrations are aected by precursor emissions and by meteorological conditions. As part of a broad study to assess the eects of standards imposed by the U.S. Environmental Protection Agency (EPA), it is of interest to analyze trends in ozone after adjusting for meteorological in¯uences. Previous papers have studied this problem for ozone data from Chicago, using a variety of regression techniques. This paper presents a dierent approach, in which the meteorological in¯uence is treated nonlinearly through a regression tree. A particular advantage of this approach is that it allows us to consider dierent trends within the clusters produced by the regression tree analysis. The variability of trend estimates between clusters is reduced by applying an empirical Bayes adjustment. The results con®rm the ®ndings of previous authors that there is an overall downward trend in Chicago ozone values, but they also go beyond previous analyses by showing that the trend is stronger at higher levels of ozone.