Potential contribution of faeces to resuspended PM1−10 in urban environment

The respirable fraction of resuspended urban road dust contains phosphorous at enhanced concentrations which may imply the potential presence of animal faeces.Specific biomarkers such as faecal sterols and bile acids are commonly used to verify the presence of faecal pollution in various environmental samples. The quantification of faecal materials in matrices is usually based on the analysis of bile acids which are persistent and refractory, and can be found in the digestive systems of all mammals and birds. In this study, by measuring the concentrations of bile acids in resuspended PM1−10 samples collected from paved roads on urban locations for the first time in aerosol science we have attempted to estimate the potential mass contribution of animals' faeces to the respirable fraction of road dust. A special sampling unit was applied for the collection of resuspended and respirable road dust in Veszprém and Budapest, Hungary. The concentrations of bile acids were determined by gas chromatography−mass spectrometry (GC−MS). Elemental phosphorous was found in the resuspended PM1−10 fraction in concentrations of 2 mg g−1 whereas the total concentrations of bile acids such as LCA (lithocholic acid), DCA (deoxycholic acid), CDCA (chenodeoxycholic acids), and HDCA (hyodeoxycholic acid) were in the order of 10 μg g−1. Based on the measured mass concentrations of bile acids, the estimated mass contribution of faeces to resuspended PM1−10 mass was found to be in the range of 0.02–0.54 m/m%. Our results imply that wind- or traffic-driven resuspension of dried animals’ faeces, which has never been considered as a potential source of urban PM1−10, is a detectable contributor to urban PM1−10 with all its potential health and epidemiological implications.