Impact of urbanization on local air quality: differences in urban and rural areas of Balikesir, Turkey

Abstract

Ozone (O-3) is a secondary pollutant which is produced photo-chemically by reactions involving NOx and benzene, toluene, ethylbenzene, and m-, p-xylenes (BTEX) in the presence of sunlight. The present study determined outdoor air quality in both the urban area of Balikesir City and rural area (around Ikizcetepeler Dam) in the same region in the western part of Turkey. The main objectives of this study were to analyze the temporal evolution and qualify the spatial distribution by using geostatistical techniques; to determine the spatial variability of air pollutants using the spatial auto-correlation statistic; and to identify the local spatial patterns of the pollutants in order to highlight the areas of potential risk of O-3, NO2, and BTEX pollution and its possible causes. For this purpose firstly, the data were compiled by using passive sampling in winter and in summer. Concentrations of O-3 ranged from 14.03 to 42.43g/m(3) in winter and from 81.79 to 70.39g/m(3) in summer in urban area. The mean NO2 and BTEX concentrations varied between sites, while mean winter concentrations were higher than the mean in summer. During winter seasons, the motorway, residential areas, urban traffic, and industrial sites showed high BTEX levels compared to the suburban and rural sites. This paper investigates the spatial mapping of temporal trends in air quality for both urban and rural areas for annual, summer and winter means. The global Moran's I result demonstrated that O-3, NO2, and BTEX had significant positive global spatial correlations. In addition, the results of local spatial auto-correlation analysis showed the locations of significant high-high spatial clusters and low-low spatial outliers.