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De Prins S.,Flemish Institute for Technological Research | De Prins S.,University of Antwerp | Koppen G.,Flemish Institute for Technological Research | Jacobs G.,Flemish Institute for Technological Research | And 13 more authors.
Environment International | Year: 2013

Background: DNA methylation changes are potential pathways of environmentally induced health effects. We investigated whether exposure to ambient concentrations of NO2, PM10, PM2.5 and O3 and traffic parameters were associated with global DNA methylation in blood of healthy adults. Methods: 48 non-smoking adults (25 males) with a median age of 39years were sampled in winter and summer. Global DNA methylation in whole blood (% 5-methyl-2'-deoxycytidine, %5mdC) was analyzed with HPLC. Exposure to air pollutants at the home address was assessed using interpolated NO2, PM10, PM2.5 and O3 concentrations for various exposure windows (60- to 1-day moving average exposures and yearly averages) and GIS-based traffic parameters. Associations between pollutants and %5mdC were tested with multiple mixed effects regression models. Results: Average %5mdC (SD) was 4.30 (0.08) in winter and 4.29 (0.08) in summer. Men had higher %5mdC compared to women both in winter (4.32 vs. 4.26) and summer (4.31 vs. 4.27). When winter and summer data were analyzed together, various NO2, PM10 and PM2.5 moving average exposures were associated with changes in %5mdC (95% CI) ranging from -0.04 (-0.09 to 0.00) to -0.14 (-0.28 to 0.00) per IQR increase in pollutant. NO2, PM10, PM2.5 and O3 moving average exposures were associated with decreased %5mdC (95% CI) varying between -0.01 (-0.03 to 0.00) and -0.17 (-0.27 to -0.06) per IQR increase in pollutant in summer but not in winter. Conclusion: Decreased global DNA methylation in whole blood was associated with exposure to NO2, PM10, PM2.5 and O3 at the home addresses of non- adults. Most effects were observed for the 5- to 30-day moving average exposures. © 2013 Elsevier Ltd. Source


Adriaenssens S.,Ghent University | Adriaenssens S.,Belgian Interregional Environment Agency IRCEL | Staelens J.,Ghent University | Staelens J.,Flemish Environment Agency VMM | And 7 more authors.
Water, Air, and Soil Pollution | Year: 2012

Tree canopies are believed to act as a sink of atmospheric ammonia (NH 3). However, few studies have compared the uptake efficiency of different tree species. This study assessed the uptake of 15N- labelled NH3 at 5, 20, 50 and 100 ppbv by leaves and twigs of potted silver birch, European beech, pedunculate oak and Scots pine saplings in June, August and September 2008. Additionally, foliar uptake of 13C- labelled carbon dioxide (13CO2) and leaf stomatal characteristics were determined per species and treatment date and the relation with 15NH3 uptake and estimated stomatal 15NH3 uptake were assessed. Both 15NH 3 and 13CO2 uptake were affected by tree species and treatment date, but only 15NH3 uptake was influenced by the applied NH3 concentration. Depending on the treatment date, 15NH3 uptake by leaves and twigs was highest at 5 (September), 20 (June) or 50 (August) ppbv. Birch, beech and oak leaves showed the highest uptake in August, while for pine needles this was in June and, except at 5 ppbv in June, the 15NH3 uptake was always higher for the deciduous species than for pine. For all species except beech 13CO2 uptake was highest in August and on every treatment date the 13CO2 uptake by leaves of deciduous species was significantly higher than by pine needles. Leaf characteristics and 13CO2 uptake did not provide a strong explanation for the observed differences in 15NH3 uptake. This study shows that on the short-term a high interspecific variability exists in NH3 uptake, which depends on the time in the growing season. © Springer Science+Business Media B.V. 2012. Source


Janssen S.,Flemish Institute for Technological Research | Dumont G.,Belgian Interregional Environment Agency IRCEL | Fierens F.,Belgian Interregional Environment Agency IRCEL | Deutsch F.,Flemish Institute for Technological Research | And 4 more authors.
Atmospheric Environment | Year: 2012

The spatial representativeness of air quality monitoring stations is a crucial parameter when the observed concentration levels are used in an air quality assessment. Spatial representativeness defines to what extent the monitoring data is meaningful and useful in a spatial context. Within this paper a generic and robust methodology is presented for the assessment of the spatial representativeness of air pollution monitoring sites. The methodology relies on a statistical approach that links annual averaged concentration levels with land use characteristics. The methodology is demonstrated for the monitoring sites in the Belgian telemetric air quality network and then applied to define a set of zones with a given confidence level. Within such a zone the concentrations deviate to a maximum percentage from the measured values at the monitoring sites. Furthermore, the relevance of spatial representativeness for model validation is addressed and the technique is illustrated for the validation of the results of the regional air quality model BelEUROS. In general, the overall improvement of the model validation by taking into account spatial representativeness can be quantified as in the order of 20%. © 2012 Elsevier Ltd. Source

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