Academic journal article Contemporary Economic Policy

Economic Valuation of Ozone-Related School Absences in the South Coast Air Basin of California

Academic journal article Contemporary Economic Policy

Economic Valuation of Ozone-Related School Absences in the South Coast Air Basin of California

Article excerpt

I. INTRODUCTION

Although ozone concentrations have fallen substantially in the South Coast Air Basin (SoCAB) of southern California over the past decade, the health-based state air quality standards (AQS) are still violated on a significant number of days each year. Ozone is associated with a variety of adverse health effects, ranging from throat and eye irritation to exacerbation of asthma and cardiac conditions. Children are recognized to be one of the groups most sensitive to ozone. In general, they are more vulnerable than adults because of their size and physical immaturity and their tendency both to be more active and to spend more time out of doors (where ozone levels are higher). At the same time, there is evidence that both families and society place greater weight on avoiding adverse health effects in a child than in an adult. (1) The focus of public policy regarding children's health and the environment has also sharpened with Executive Order 13045 in 1997 (Federal Register, 1997) and subsequent actions by federal agencies, including the U.S. Environmental Protection Agency's (EPA) formation of the Children's Health Protection Advisory Committee.

Recent advances in health research have documented the association between ozone levels and school absences (see Gilliland et al., 2001). This research provides the necessary concentration-response functions to support economic valuation of this adverse health effect in children in southern California. This effect is important because it occurs much more frequently than previously measured effects on children, such as emergency room visits and hospital admissions. An assessment of the economic benefits of reducing school absences can help establish more concretely the benefits that have been realized from past ozone reductions and suggest the magnitude of benefits from further progress toward the health-based standards.

This study provides an estimate of the reduction in ozone-related school absences in southern California over the decade of the 1990s. The population cohort is children aged 5-18 residing in the SoCAB. The authors estimate reductions in the number of days of all respiratory illness related absences, the number of days of all illness-related absences, and the economic loss to families of these absences. To highlight the decline in ozone levels across the decade, the study also disaggregates the results and reports estimates for rolling three-year intervals from 1990-92 to 1997-99.

In the next section, the authors describe their integrated approach--economists working collaboratively with atmospheric modelers and health specialists--and related assessments methods. They then present and discuss the results of the analysis, followed by some conclusions and recommendations for future research.

II. INTEGRATED APPROACH AND ASSESSMENT METHODS

Estimating the health benefits of reducing exposure to ozone is based on integrating air quality and population data with concentration-response relationships for specific adverse health effects to first estimate changes in exposure and associated reductions in the number of adverse effects. An economic value per unit of each effect is then used to measure the dollar value of improved health. This approach is somewhat different from most benefit assessments (for example, the EPA retrospective and prospective assessments of the benefits of the Clean Air Act) because the authors use a set of models that support the full use of air quality and demographic data to develop a very detailed spatial estimate of pollution exposure by cohort. In this case they use this capability to assess school absences for children by geographic region and across the SoCAB.

A. Exposure Modeling and Estimation

The Regional Human Exposure (REHEX) model is a computer model designed to estimate population exposure to various air pollutants. Researchers first developed the model to support assessment of the economic benefits of attaining AQSs in the SoCAB (Winer et al. …

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