Particulate Matter Exposure of Rural Interior Communities as Observed by the First Tribal Air Quality Network in the Yukon Flat

Abstract

A tribal-owned network of aerosol monitors and meteorological stations was installed at Ts'aahudaaneekk'onh Denh (Beaver), Gwichyaa Zheh (Fort Yukon), Jałgiitsik (Chalkyitsik), and Danzhit Khànląįį (Circle) in the Yukon Flats, Alaska. Surface inversions occurred under calm wind conditions due to radiative cooling. In May, local emissions governed air quality with worst conditions related to road and river dust. As the warm season progressed, worst air quality was due to transport of pollutants from upwind wildfires. During situations without smoke or when smoke existed at layers above the surface inversion, concentrations of particulate matter of less than 2.5 micrometer in diameter or less (PM 2.5) were explainable by the local emissions; 24-h means remained below 25 μg•m −3. Absorption of solar radiation in the smoke layer and upward scattering enhanced stability and fostered the persistence of the surface inversions. During smoke episodes without the presence of a surface inversion, daily mean concentrations exceeded 35 μg•m −3 often for several consecutive days, at all sites. Then concentrations temporally reached levels considered unhealthy.

Mesoscale Impacts on Cold Season PM<sub>2.5</sub> in the Yukon Flats

“…In addition, emissions from open wood-fires for cooking dog food exist; typically, they occur in the evening in winter. Emissions from heating decrease with increasing air temperature and vice versa [11]. In Ft. Yukon, Beaver and Chalkyitsik, passenger cars, trucks and heavy equipment exist despite there is no access to the Alaska road network.…”

“…Data files were synchronized and underwent the quality assurance/quality control (QA/QC) protocol as described in [11]. Data used in this study are April whether they showed similar behavior as those data that represented the conditions after the Sun raised above the horizon after winter solstice.…”

“…Off-road traffic emissions stem from four-wheelers and snow mobiles. Typically, emissions from traffic decrease with increasing air temperature and vice versa [11].…”

“…Figure 3 exemplarily shows the annual emission totals from airport emissions for various communities in the Yukon Flats. For details on the emission sources see [11].…”

“…Despite the Yukon Flats are Interior Alaska's largest valley, no radiosonde sites and only three surface meteorological sites exist. No pollution observations exist except for some recent PM 2.5 measurements performed at four sites and black carbon measurements at two sites during one wildfire season (mid-May to mid-September) [11] [12]. The reasons for the lack of air-quality measurements in the Yukon Flats are manifold.…”