Spatial and temporal variability of PM₁₀ sources in Augsburg, Germany.

Source apportionment of ambient particulate matter (PM10) was carried out using daily chemical composition data collected in winter 2006/07 and winter 2007/08 in Augsburg, Germany. Six factors have been identified and were associated with secondary nitrate, secondary sulfate, residential and commercial combustion, NaCl, re-suspended dust and traffic emissions. Comparing the source profiles between winter 2006/07 and winter 2007/08 showed that they were similar for both winters, except the combustion and traffic emissions factors. The spatial variation of particulate sources was evaluated by analysis of data collected at eight sampling sites during a one-month intensive campaign in winter 2007/08. Secondary nitrate, secondary sulfate as well as residential and commercial combustion factors showed strong correlations and low coefficient of divergence (COD) values among eight sites, indicating that they are uniformly distributed in urban area. By contrast, traffic emissions factor and NaCl were highly heterogeneously distributed. These two factors were enhanced greatly at the traffic site and are the cause of elevated PM10 mass concentration at traffic site. It means that for some specific sources of particles showing pronounced spatial variability a central monitoring site could not assess the absolute concentrations across an urban area. Thus, cautions should be taken when approximating average human exposure to these particle sources in long-term epidemiological studies