NOx emissions analysis comparing DEIS and SEIS scenarios for Sea-Tac Airport operations

A critic of the Sea-Tac Airport environmental review process argues that the Supplemental EIS (SEIS) inconsistently reports nitrogen oxide (NOx) pollution levels, showing decreasing or flat emissions even as annual aircraft operations increase significantly. The author contends the SEIS analysis appears biased to keep pollution figures below regulatory thresholds, contradicting earlier independent studies. Using a consistent per-plane emissions rate, the author recalculates that NOx tonnage should rise substantially alongside the projected growth in flight operations.

Notes

A critical analysis comparing nitrogen oxide (NOx) emissions data across multiple environmental impact studies for Sea-Tac Airport, arguing that the SEIS analysis is biased and inconsistent with previous studies. The author contends that despite significant increases in annual aircraft operations, the SEIS reports implausibly low NOx increases, and provides alternative calculations based on average fleet mix data. The document raises concerns about the absence of dispersion analysis for higher-operation scenarios.

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