Model assessment and verification - Air Pollution Modeling and Its Application - page 370

4.18 Influence of Concentration-Response Temporal
Metrics on Control Strategy Optimization

Daniel S. Cohan 1 , Antara Digar 1 , and Michelle L. Bell 2

1

Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005,
USA
2

School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA

Abstract Epidemiological studies differ as to the temporal averaging periods that
govern air pollutant health impacts, and the presence of threshold concentrations
at which impacts begin to occur. Here, we investigate how alternate temporal
metrics and thresholds for ozone concentration-response functions could influence
the optimization of control strategies for health benefits. A photochemical model
is applied with direct sensitivity analysis to simulate the responsiveness of ozone
to potential regional and point source emissions controls in a summertime air
pollution episodes in Georgia. The relative health benefits of various control
options are assessed by linking the DDM sensitivity results with population and
applying alternate temporal metrics for ozone health impacts. We assess how these
metrics influence the relative health impacts of alternate control options.

Keywords Ozone health effects, temporal metrics, decoupled direct method,
sensitivity analysis

1. Introduction

Air quality management aims to achieve two interrelated yet distinct objectives:
attainment of ambient standards, and protection of public health. In the develop-
ment of state implementation plans (SIPs), policy-makers in U.S. states have typically
focused on how to achieve National Ambient Air Quality Standards (NAAQS) in
the most expedient and cost-effective manner, without explicit quantification of
health benefits. An implicit assumption in these efforts is that regulatory attainment
will be sufficiently protective of human health, since the U.S. Clean Air Act mandates
that NAAQS be set so as to protect human health with an “adequate margin of safety.”
Recent work has explored how health implications could be explicitly considered
in the development of air quality attainment plans (Cohan et al., 2007). Some
epidemiological studies suggest that no clear thresholds exist for air pollution
health effects, and that health benefits may result from air quality improvements
beyond the NAAQS requirements (Bell et al., 2006) Consideration of health impacts