Atmospheric concentrations of SO2, NO2, ozone and VOCs in Duzce, Turkey using passive air samplers: Sources, spatial and seasonal variations and health risk estimation
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In this research, seasonal and spatial distributions of inorganic and organic pollutants (sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O-3) and also volatile organic compounds (VOCs)), were determined by passive sampling technique. Fifty sampling sites were selected considering possible sources in the study area. The sampling area were classified as urban (n=23), industrial (n=17) and rural (n=10) regions. Sampling campaigns were carried out for two-week periods in fall, winter, spring and summer seasons in all regions. Benzene and toluene concentrations were found to be the highest in winter at the traffic-dense sites and lowest concentrations were measured at rural sampling sites in summer. Concentrations of NO2 were higher at sampling sites with high traffic density in winter. A much uniform distribution was observed for SO2 in all seasons. However higher levels were observed in winter compared to other seasons due to use of coal for domestic heating. Low O-3 concentrations were measured in winter while higher concentrations were measured in summer. Based on principal component analysis (PCA), four factors (gasoline vehicle emissions, diesel vehicle emissions, industrial emissions and fossil fuel combustion) were identified that could explain about 78% of the system variance of the measured pollutants in the city. Health risk assessment revealed that the safe level of 1 x 10(-6) (United States Environmental Protection Agency's (USEPA) acceptable risk value) was exceeded for benzene in all sampling sites in whole region, but non-carcinogenic risk values were at safe level.