As part of the outer cell wall of gram-negative bacteria endotoxins can be found ubiquitous in nature. So far most studies on airborne endotoxins focussed on occupational environments. In Germany IFA-Arbeitsmappe 9450 gives recommendations for sampling and analysis of endotoxins at workplaces. However, apart from background measurements for workplace evaluations, there are currently no guidelines in Germany for endotoxin measurements at environmental settings. Therefore, the aim of this study was to test whether PM10 sampling on filters with a high volume sampler and determination of endotoxin concentration via LAL assay are suitable methods for a new guideline for measurement of endotoxin concentration in ambient air. Over the course of one year endotoxin concentration was investigated at three different rural sampling spots. Annual median endotoxin concentration over all samples was 0.143 EU/m³. Between different sampling spots no significant differences in endotoxin concentrations were observed, yet endotoxin concentration in ambient air showed an obvious seasonal course. The applied methods have proven suitable for the analysis of endotoxins in the outdoor air, although further standardization is needed before implementation in a guideline.

This article is published in the Journal "Gefahrstoffe - Reinhaltung der Luft", Volume 81, Issue 11-12, pp. 443-446 (www.gefahrstoffe.de).