Indoor and outdoor BTX levels in German cities

On the basis of the ongoing study INGA (INdoor exposure and Genetics in Ast hma), Germany's most detailed and standardized epidemiological study on ind oor exposure to both allergens in house dust and volatile compounds in the air of the home environment has been performed. The purpose of this paper i s to describe the spatial and seasonal variability of indoor and outdoor BT X (Benzene, toluene, ethyl benzene, ortho-xylene, meta- and para-xylene) co ncentrations for the study period from June 1995 to November 1996. Within t his framework, air concentrations of volatile organic compounds (BTX) were measured in 204 households in Erfurt (Eastern Germany) and 201 households i n Hamburg (Western Germany). BTX sampling was conducted over one week using OVM 3500 passive diffusion sampling devices in the indoor (living room and bedroom) and outdoor environment (outside the window of the living room). Indoor and outdoor median BTX concentrations in Erfurt were slightly, but s ignificantly higher than those in Hamburg. This gap was most pronounced in the levels of indoor toluene (37.3 mug/m(3) for Erfurt and 20.5 mug/m(3) fo r Hamburg, P < 0.0001). In both cities, winter indoor and outdoor concentra tions for the five compounds exceeded the summer values. Outdoor concentrat ions of ethyl benzene and ortho-xylene were very low (50% < L.D.). In gener al, the indoor BTX air concentrations were significantly higher than the ou tdoor concentrations, the lowest I/O ratios were found in the case of benze ne. Living room and bedroom values for the five compounds were highly corre lated (Spearman coefficient 0.5-0.9). Despite the better insulation of the homes in West Germany, no indication for the expected higher indoor concent rations of BTX in the West could be found. The strong and yet undiscovered indoor source for toluene in East Germany might lead to a further increase in the indoor air load in those homes in the East, which undergo renovation s which will lead to improved insulation (C) 2001 Elsevier Science B.V. All rights reserved.