gms | German Medical Science

50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds)
12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie (dae)

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie
Deutsche Arbeitsgemeinschaft für Epidemiologie

12. bis 15.09.2005, Freiburg im Breisgau

Spatial Variation of Endotoxin in Ambient Particulate Matter across a German Metropolitan Area

Meeting Abstract

  • Verena Morgenstern - GSF - National Research Center for Environment and Health, Neuherberg
  • Cara L. Carty - GSF - National Research Center for Environment and Health, Neuherberg
  • Ulrike Gehring - GSF - National Research Center for Environment and Health, Neuherberg
  • Josef Cyrys - GSF - National Research Center for Environment and Health, Neuherberg
  • Wolfgang Bischof - Friedrich-Schiller University of Jena, Institute of Occupational, Social and Environmental Medicine & Hygiene, Dept. Indoor Climatology, Jena, Germany
  • Joachim Heinrich - GSF - National Research Center for Environment and Health, Neuherberg

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie. Deutsche Arbeitsgemeinschaft für Epidemiologie. 50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds), 12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie. Freiburg im Breisgau, 12.-15.09.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05gmds090

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/gmds2005/05gmds008.shtml

Veröffentlicht: 8. September 2005

© 2005 Morgenstern et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction

As part of an international collaborative study on the impact of Traffic-Related Air Pollution on Childhood Asthma (TRAPCA), we sampled fine and inhalable particulate matter with a 50% aerodynamic cutoff diameter of 2.5 µm (PM2.5) at 40 monitoring sites and of 10 µm (PM10) at 12 monitoring sites in ambient air across Munich, Germany for 17 months [1], [2]. In the current study, we used these sampled particles and determined endotoxin concentrations in PM2.5 and PM10. We report endotoxin levels in PM2.5 and PM10 per miligram and per cubic meter of sampled air and to describe spatial variation of endotoxin across Munich, a German metropolitan area. The goals of our study were to determine ambient endotoxin levels in PM2.5 and PM10 in the metropolitan area of Munich and describe the spatial variation of endotoxin in PM2.5 across the city using GIS methods. We also investigate whether potential sources of endotoxin are useful in predicting endotoxin ambient levels.

Materials and Methods

All particulate matter measurements were made during two-week intervals between March 1999 and July 2000. Sampling periods were approximately 14 days, during which air was sampled for 15 minutes every two hours for a total of approximately 42 hours each sampling period. Using Teflon filters and Harvard Impactors, PM2.5 was collected at 40 outdoor monitoring sites across Munich and PM10 at a subset of these sites (n=12). For further details about the measurement see [3]. Approximately four samples were collected at each site for a total of 158 PM2.5 samples and 48 PM10 samples. We visited all forty measurement sites and examined the surrounding 100 meters with regard to trash bins, compost bins, kitchens, sewage, gardens, animals and breweries which we classified as potential sources for higher endotoxin levels. Apart from this information, we used GIS data to describe the measurement sites.

Since the distribution of measured concentrations was skewed to the right, we used the geometric means to report mean concentrations for the four samples for each monitoring site. In order to obtain a map of endotoxin concentrations in PM2.5 for the whole city area, we used the Inverse Distance Weighting Method (IDW), which calculates a value for each grid node by examining surrounding data points that lie within a special radius.

Results

The geometric mean endotoxin concentration for all sites was 1.46 EU/mg PM2.5 (95% CI: 1.21 - 1.77) and at the subset of the sites was 1.30 EU/mg PM2.5 (95% CI: 1.01 - 1.67 EU/mg PM2.5). Endotoxin levels in PM10 were higher, 3.91 EU/mg PM10 (95% CI: 3.03 - 5.03 EU/mg PM10), than in PM2.5 and were moderately correlated, r=0.51. The number of potential sources were combined into one categorical variable and we found out that sites with more potential sources (n>=3) had slightly higher mean endotoxin levels (MR: 1.30 for EU/mg PM2.5 and 1.13 for EU/m3 PM2.5) than sites with no identified sources (see Table 1 [Tab. 1] for EU/mg PM2.5).

Based on the ranges of endotoxin levels at the different sites, we found little spatial variation in ambient endotoxin concentrations across the metropolitan area of Munich using IDW methods. Potential sources of endotoxin surrounding the sites only partly explained the variation seen (see Figure 1 [Fig. 1])

Discussion

Athough there is little spatial variation in ambient endotoxin concentrations across Munich, there is no difference in geometric mean levels of endotoxin between the city center and the periphery. Possibly due to the low spatial variability in endotoxin or to the site selection, no clear spatial patterns were found. Potential sources of endotoxin surrounding the sites weakly explained the variation seen. The endotoxin levels in PM2.5 and in PM10 were moderately highly correlated. Future studies on the spatial variation of ambient endotoxin should focus on careful selection of monitoring sites, because the sites of this study were selected in relation to traffic volume as the major source of interest. Although they were moderately correlated in this study, endotoxin content in different particulate size fractions may also need to be considered.


References

1.
Hoek G, Meliefste K, Cyrys J, Lewne M, Bellander T, Brauer M et al. Spatial variability of fine particle concentrations in three European areas. Atmospheric Environment 2002; 36(25):4077-4088.
2.
Gehring U, Cyrys J, Sedlmeir G, Brunekreef B, Bellander T, Fischer P et al. Traffic-related air pollution and respiratory health during the first 2 yrs of life. Eur Respir J 2002; 19:690-698
3.
Carty CL, Gehring U, Cyrys J, Bischof W, Heinrich J. Seasonal variability of endotoxin in ambient fine particulate matter. Journal of Environmental Monitoring 2003; 5(6):953-958