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P. L. Jackson et al.
system was applied to all known sources of PM 10 , PM 2.5 , NO x and SO 2 affecting
the Prince George airshed over the three-year period 2003–2005. The model results
were evaluated by comparison with ambient levels as well as with results from a
speciation study using Positive Matrix Factorization and Chemical Mass Balance
techniques. This resulted in constraints on the emissions of some of the more poorly
characterized sources. In addition, a web-based visualization and scenario tool was
developed for air quality managers to enable them to make science-based decisions
to improve air quality. The results of the modelling and source attribution will be
discussed, and the web-based scenario tool demonstrated.
14.1 Introduction
Prince George, British Columbia (BC) Canada is a city of 74,000 [1] located at the
junction of the Fraser and Nechako Rivers in a valley about 150 m below the BC
Central Interior Plateau. Prince George has among the highest levels of PM 2.5 in
Western Canada, although it generally meets the BC ambient air quality objective of
8 µg m
−3 , it occasionally exceeds the 24 h average standard of 25 µg m
−3 . Three
kraft pulp mills (east and northeast of the downtown central business district), and
other industrial sources in Prince George contribute significant amounts of PM 2.5
to the airshed, mainly through combustion of biomass [2]. Other important anthropogenic sources of PM 2.5 in the Prince George area include open burning of wood
debris, wood burning for residential heating during the winter, cooking from commercial and household stoves, locomotive emissions, and diesel and gasoline vehicle
combustion engines [2], as well as anthropogenic dust sources such as road dust and
fugitive dust. The wind-sheltered valley area of Prince George experiences frequent
temperature inversions associated with stagnant air conditions that often result in
elevated pollution levels [4]. Winter meteorological conditions can result in more
frequent temperature inversions in the valley, less atmospheric mixing from daytime
solar radiation heating of the surface, and consequently higher levels of PM 2.5 pollution [2, 4]. Between 2005 and 2016, deseasonalized monthly mean Prince George
PM 2.5 levels have been decreasing at 0.16 µg m
−3 year
−1 , while 98th percentile
levels have been decreasing at 0.66 µg m
−3 year
−1 [3]. Based on a wind-sector analysis, these improvements were largely driven by environmental upgrades at major
industrial sources to the northeast of the Prince George downtown.
In order to better understand the contribution of specific sources to ambient PM 2.5
levels in Prince George and guide air quality management, a community-wide modelling study was conducted to simulate the transport and dispersion of all identifiable
PM 2.5 sources. In order to help air quality managers understand and visualize the
model results, a web-based decision support tool, called AirQuest was developed.
This paper describes the modelling study and the visualization tool.
P. L. Jackson et al.
system was applied to all known sources of PM 10 , PM 2.5 , NO x and SO 2 affecting
the Prince George airshed over the three-year period 2003–2005. The model results
were evaluated by comparison with ambient levels as well as with results from a
speciation study using Positive Matrix Factorization and Chemical Mass Balance
techniques. This resulted in constraints on the emissions of some of the more poorly
characterized sources. In addition, a web-based visualization and scenario tool was
developed for air quality managers to enable them to make science-based decisions
to improve air quality. The results of the modelling and source attribution will be
discussed, and the web-based scenario tool demonstrated.
14.1 Introduction
Prince George, British Columbia (BC) Canada is a city of 74,000 [1] located at the
junction of the Fraser and Nechako Rivers in a valley about 150 m below the BC
Central Interior Plateau. Prince George has among the highest levels of PM 2.5 in
Western Canada, although it generally meets the BC ambient air quality objective of
8 µg m
−3 , it occasionally exceeds the 24 h average standard of 25 µg m
−3 . Three
kraft pulp mills (east and northeast of the downtown central business district), and
other industrial sources in Prince George contribute significant amounts of PM 2.5
to the airshed, mainly through combustion of biomass [2]. Other important anthropogenic sources of PM 2.5 in the Prince George area include open burning of wood
debris, wood burning for residential heating during the winter, cooking from commercial and household stoves, locomotive emissions, and diesel and gasoline vehicle
combustion engines [2], as well as anthropogenic dust sources such as road dust and
fugitive dust. The wind-sheltered valley area of Prince George experiences frequent
temperature inversions associated with stagnant air conditions that often result in
elevated pollution levels [4]. Winter meteorological conditions can result in more
frequent temperature inversions in the valley, less atmospheric mixing from daytime
solar radiation heating of the surface, and consequently higher levels of PM 2.5 pollution [2, 4]. Between 2005 and 2016, deseasonalized monthly mean Prince George
PM 2.5 levels have been decreasing at 0.16 µg m
−3 year
−1 , while 98th percentile
levels have been decreasing at 0.66 µg m
−3 year
−1 [3]. Based on a wind-sector analysis, these improvements were largely driven by environmental upgrades at major
industrial sources to the northeast of the Prince George downtown.
In order to better understand the contribution of specific sources to ambient PM 2.5
levels in Prince George and guide air quality management, a community-wide modelling study was conducted to simulate the transport and dispersion of all identifiable
PM 2.5 sources. In order to help air quality managers understand and visualize the
model results, a web-based decision support tool, called AirQuest was developed.
This paper describes the modelling study and the visualization tool.