Long-Term Air Quality Study in Fairbanks, Alaska: Air Pollutant Temporal Variations, Correlations, and PM2.5 Source Apportionment

Abstract

As one of the most polluted U.S. cities, Fairbanks was reclassified as a “serious” nonattainment area by the Environmental Protection Agency (EPA) in 2017 for its fine particulate matter (PM2.5) pollution. In this study, November 2013–May 2019 observations of criteria air pollutants (NO2, SO2, CO, O3, PM2.5, and inhalable particulate matter (PM10)) and meteorological parameters (temperature, wind speed, and relative humidity) in Fairbanks were used for temporal variation and correlation analysis, with positive matrix factorization (EPA PMF 5.0) adopted for further PM2.5 source identification. All pollutants exhibited obvious seasonal trends under the influence of climatology, topography, and human activity, while abnormal patterns likely resulted from occasional emission events such as wildfires. Primary and secondary pollutants performed distinctively under similar meteorological conditions due to different decisive factors. Identified PM2.5 sources included sulfate (32.7%), wood smoke (19.3%), gasoline (18.3%), nitrate (15.7%), diesel (9.2%), soil (3.8%), and road salt (1.0%). Compared with the 2005–2012 result, sulfate and nitrate contributions had increased, while wood smoke and diesel contributions had decreased, in which emission control measures as well as a change of sampling sites could play an important role. This systematic analysis offers reference for mitigation measures and pollution prediction. Meanwhile, further field investigation is required for conclusion validation and model improvement.