| Autor: |
Topp, Rebekka, Cyrys, Josef, Gebefügi, Istvan, Schnelle-Kreis, Jürgen, Richter, Kai, Wichmann, H.-Erich, Heinrich, Joachim |
| Zdroj: |
Journal of Environmental Monitoring; 2004, Vol. 6 Issue: 10 p807-812, 6p |
| Abstrakt: |
Studies on health effects of air pollutants ideally define exposure through the collection of air samples in the participants' homes. Concentrations derived from these samples are then considered as an estimate for the average concentration of air pollutants in the homes. Conclusions drawn from such studies therefore depend very much on the validity of the measured air pollution concentrations. In this paper we analysed repeated BTEX and NO2measurements with a time period of several months lying between the two conducted home visits. We investigated the variability of their concentrations over time by determining correlation coefficients and calculating within- and between-home variances. Our population consisted of 631 homes of participants from two cohort studies within the framework of the German study on Indoor Factors and Genetics in Asthma. Air pollutants were measured using passive samplers both indoors and outdoors. The measured BTEX concentrations were poorly correlated, with Pearson's correlation coefficient rranging from −0.19 to 0.27. Additionally, a considerable seasonal effect could be observed. A higher correlation was found for the NO2concentrations with rranging between 0.24 and 0.55. For the BTEX, the between-home variance was bigger than the within-home variance, for NO2both variances were of about the same order. Our results indicate that in a setting of moderate climate like in Germany, the variability of BTEX and NO2concentrations over time is high and a single measurement is a poor surrogate for the long-term concentrations of these air pollutants. |
| Databáze: |
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