Topp Rebekka, Cyrys Josef, Gebefügi Istvan, Schnelle-Kreis Jürgen, Richter Kai, Wichmann H-Erich, Heinrich Joachim
GSF-National Research Center for Environment Health, Institute of Epidemiology, 85764 Neuherberg, Germany.
J Environ Monit. 2004 Oct;6(10):807-12. doi: 10.1039/b405537c. Epub 2004 Aug 18.
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 NO(2) measurements 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 r ranging from -0.19 to 0.27. Additionally, a considerable seasonal effect could be observed. A higher correlation was found for the NO(2) concentrations with r ranging between 0.24 and 0.55. For the BTEX, the between-home variance was bigger than the within-home variance, for NO(2) both 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 NO(2) concentrations over time is high and a single measurement is a poor surrogate for the long-term concentrations of these air pollutants.
关于空气污染物对健康影响的研究，理想情况下是通过在参与者家中采集空气样本确定暴露情况。然后将这些样本得出的浓度视为家庭中空气污染物平均浓度的估计值。因此，此类研究得出的结论在很大程度上取决于所测空气污染浓度的有效性。在本文中，我们分析了两次家访之间间隔数月的苯系物和二氧化氮的重复测量数据。我们通过确定相关系数以及计算家庭内部和家庭之间的方差，研究了它们浓度随时间的变化情况。我们的研究对象包括德国室内因素与哮喘遗传学研究框架内两项队列研究中631名参与者的家庭。使用被动采样器在室内和室外测量空气污染物。所测苯系物浓度之间相关性较差，皮尔逊相关系数r在-0.19至0.27之间。此外，还观察到了明显的季节效应。二氧化氮浓度的相关性较高，r在0.24至0.55之间。对于苯系物，家庭之间的方差大于家庭内部的方差，对于二氧化氮，两者方差大致相同。我们的结果表明，在德国这样气候温和的环境中，苯系物和二氧化氮浓度随时间的变化很大，单次测量对于这些空气污染物的长期浓度而言是一个较差的替代指标。
