[en] The System Operation Review (SOR) is a study and environmental compliance process being used by the three Federal agencies to analyze future operations of the system and river use issues. The goal of the SOR is to achieve a coordinated system operation strategy for the river that better meets the needs of all river users. This technical appendix addresses only the effects of alternative system operating strategies for managing the Columbia River system. This appendix consists of eight chapters. Chapter 1 describes the air quality issues that were raised in the SOR scoping process and provides an overview of the study process used to evaluate air quality effects from various system operation alternatives. Chapter 2 describes the Federal, state, and local programs that regulate air quality and discusses the air quality standards that are relevant to the analysis. It also gives an overview of the limatology of the region and the existing air quality in the Columbia River Basin, including areas of non-attainment for relevant air quality standards. Chapter 3 presents the methods this study uses for the analysis of air quality and for the evaluation of human health effects from air pollutants. Chapter 4 provides the study results for the System Operating Strategy (SOS) alternatives and potential mitigation measures. Chapter 5 compares impacts on air quality and human health across alternatives, and discusses mitigation measures and cumulative effects. Chapters 6, 7, and 8 contain the list of preparers, glossary, and references, respectively. Technical exhibits supporting the analysis are also included