Stochastic Air Quality Analysis

Abstract

Air quality and human health are intimately connected. In many urban areas in the United States air quality becomes unacceptable several times a year. Ozone (O3) is one of the most common used criteria for judging air quality. The ozone (O3) concentration arises from photochemical reactions between oxides of nitrogen and hydrocarbons in the presence of ultraviolet light. Higher ozone concentrations usually are often observed in industrial areas and the areas with high automobile emissions of nitrogen oxides and hydrocarbons. These areas therefore tend to have higher health problems. Thus, analysis of the ozone concentration is important. Five variables pertaining to the ozone concentration can be chosen for analysis: (1) the number of days the ozone concentration exceeding the national ambient air quality standard and design value in a given year; (2) the highest ozone reading in a given year; (3) the duration of an ozone exceedance; (4) time interval between ozone exceedances; and (5) trend over time of non-attainment parishes. These variables may be inter-related and may be stochastic in nature. Using the copula concept, a stochastic analysis of the ozone violation was undertaken in this study for the city of Baton Rouge in Louisiana. Keyword: Archimedean copula, Cook-Johnson copula, EPA, Frank copula, Gumbel-Hougaard copoula, ozone.