TagDoug Urry(1)

Previous air pollution modeling efforts and current facility expansion activities at Sea-Tac International Airport have raised concerns about elevated nitrogen dioxide (NO2) levels in the surrounding community. The goals for this project were to 1) assess compliance with the 100 micrograms per cubic meter annual national ambient air quality standard (NAAQS) for NO2, 2) quantify any local concentration gradients, and 3) evaluate the impact of aircraft operations on local NO2 levels. The scope of this project included annual NO2 measurements throughout the community; samplers were located in areas near the north and south ends of the airport where aircraft operations would most likely affect ambient concentrations. Three-week integrated NO2 measurements were continuously performed at 16 locations using Yanagisawa NO2 diffusion badges. Additionally, Washington State Department of Ecology (WDOE) performed continuous nitrogen oxides (NOX) measurements using Federal Reference Method chemiluminescent analyzers and collected meteorological data at two of the sampling locations. Annual average NO2 measurements at all sites were well below the NAAQS. Consistent spatial concentration gradients were observed throughout the study. NO2 levels decreased from east to west. NO2 levels generally decreased with distance from both the airport runways and local freeways. Hourly NOX and meteorological data from WDOE monitoring stations were used to identify local source impacts by comparing measured NOX levels by wind direction. Because NOX is primarily emitted as nitric oxide (NO), concentration of this species varied more with wind direction than NO2. Evidence of a small but discernable airport impact on NOX levels was observed near…