Spatial Variation of Airborne Pollutant Concentrations in Brisbane, Australia and its Potential Impact on Population Exposure Assessment.

Spread of air pollution sources and non-uniform mixing conditions in urban or regional air sheds often result in spatial variation of pollutant concentrations over different parts of the air sheds. A comprehensive understanding of this variation of concentrations is imperative for informed planning, monitoring and assessment in a range of critical areas including assessment of monitoring network efficiency or assessment of population exposure variation as a function of the location in the city. The aims of this work were to study the city-wide variability of pollutants as measured by "urban background" type monitoring stations and to interpret the results in relation to the applicability of the data to population exposure assessments and the network efficiency. A comparison between ambient concentrations of NOx, ozone and PM10 was made for three stations in the Brisbane air shed network. The best correlated between the three stations were ozone concentrations followed by NOx concentration, with the worst correlations observed for PM10. With a few exceptions correlations of all pollutants between the stations were statistically significant. Marginally better were the correlations for the lower concentrations of pollutants that represent urban background, over the correlations for higher concentrations, representing peak values. Implications of these findings on application of the monitoring data to air quality management, as well as the need for further investigations has been discussed.