Moreover, a 1% increase in the share of agriculture in value added is associated with an increase of 0.11% in SO2 concentration. In contrast to other pollutants, the degree of fragmentation of an urban area does not appear to affect SO2 concentration. This might be due to the fact that SO2 is mainly produced by energy generation processes rather than by road transportation. In particular, this study presents evidence that urban fragmentation is correlated with higher concentrations of NO2 and PM10, when controlling for economic factors and climate conditions. Moreover, the results suggest that densely populated urban areas are associated with higher SO2 concentrations.