TagClean Air Act(22)

In a 1996 letter to the Federal Aviation Administration, the U.S. Environmental Protection Agency (EPA) Region 10 raised concerns about air quality impacts from the proposed Master Plan expansion at Seattle-Tacoma International Airport, noting that the project was projected to worsen carbon monoxide levels at nearby intersections in violation of federal air quality standards. The EPA called for a comprehensive emissions inventory, a comparison of air quality with and without the project, and enforceable mitigation measures, while also highlighting inconsistencies in air quality modeling across multiple related development projects in the airport area. The agency urged the FAA and Port of Seattle to coordinate data sharing with regional authorities and establish a long-term air quality monitoring program to address cumulative impacts from surrounding projects.

A 1996 air quality review commissioned by the Airport Communities Coalition challenges the FAA's finding that Sea-Tac Airport's Master Plan Update would not worsen air pollution. Envirometrics, Inc. found that if the proposed third runway increased airport operations—by up to 33% annually and 50% during peak hours—carbon monoxide (CO) and nitrogen dioxide (NO₂) levels would exceed federal air quality standards at multiple locations near the airport. The report concludes that these increased emissions from greater aircraft and vehicle traffic would delay attainment of ambient air quality standards in the surrounding communities.