F Fierens

Belgian Development Agency, Bruxelles, Brussels Capital Region, Belgium

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Publications (5)9.47 Total impact

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    ABSTRACT: Background Studies in populations have shown that particulate air pollution is associated with changes in lung function in adolescents. Objective We investigated the effect of short- and long-term exposure to particulate matter (PM10) on the pulmonary health of adolescents, using serum lung club cell secretory protein (Clara) (CC16) as a biomarker for respiratory epithelium integrity. Methods We measured serum CC16 in 825 adolescents (57% girls, mean age: 15 years). Short-term and long-term exposure to ambient PM10 was estimated for each participant's home address using a kriging interpolation method. To explore the association between PM10 and serum CC16 we applied restricted cubic splines with 5 knots located at the 5th, 25th, 50th, 75th and 95th percentiles of the PM10 distribution. The explorative analyses showed a change in the slope of this association, after which a change-point analysis was performed. Results After adjustment for potential covariates, the analysis showed strong associations between PM10 concentrations, averaged over the week preceding the clinical examination, and serum CC16 levels. Each 5 μg/m3 increase in mean PM10 concentration in the week before the clinical examination was associated with a substantial increase of 0.52 μg/l (95% confidence interval: 0.31 to 0.73; p < 0.0001) in serum CC16 levels. The association appears nonlinear with a flattening out of the slope at mean week PM10 levels above 37 μg/m3. There was no evidence of an association between long-term exposure to PM10 and serum CC16 concentrations. Conclusions Our findings suggest that short-term exposure to particulate air pollution may compromise the integrity of the lung epithelium and lead to increased epithelial barrier permeability in the lungs of adolescents, even at low concentrations.
    Environment International. 01/2014; 68:66–70.
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    ABSTRACT: Epidemiological studies suggest an association between exposure to particulate matter (PM) in air pollution and the risk of venous thromboembolism (VTE). To investigate the underlying pathophysiological pathways linking PM exposure and VTE. We assessed potential associations between PM exposure and coagulation and inflammation parameters, including circulating microvesicles, in a group of 233 patients with diabetes. The numbers of circulating blood platelet-derived and annexin V-binding microvesicles were inversely associated with the current levels of PM(2.5) or PM(10), measured on the day of sampling. Recent past exposure to PM(10), up to 1 week prior to blood sampling, estimated at the patients' residential addresses, was associated with elevated high-sensitivity C-reactive protein (CRP), leukocytes and fibrinogen, as well as with tissue factor (TF)-dependent procoagulant changes in thrombin generation assays. When longer windows of past exposure were considered, up to 1 year preceding blood sampling, procoagulant changes were evident from the strongly increased numbers of red blood cell-derived circulating microvesicles and annexin V-binding microvesicles, but they no longer associated with TF. Past PM exposure was never associated with activated partial thromboplastin time (aPTT), prothrombin time (PT), or factor (F) VII, FVIII, FXII or D-dimers. Residential distance to a major road was only marginally correlated with procoagulant changes in FVIII and thrombin generation. Increases in the number of microvesicles and in their procoagulant properties, rather than increases in coagulation factors per se, seem to contribute to the risk of VTE, developing during prolonged exposure to air pollutants.
    Journal of Thrombosis and Haemostasis 11/2011; 10(1):96-106. · 6.08 Impact Factor
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    ABSTRACT: Numerous studies have shown a strong association between daily mortality and small particulate with a diameter of <10 microm (PM10) air pollution, but the effects of season have not always been well characterised. To study the shape of the association between short-term mortality and PM10 across seasons and quintiles of outdoor temperature. Daily data on mortality (n = 354 357), outdoor temperature and PM10 in Flanders, Belgium, from January 1997 to December 2003, were analysed across warm versus cold periods of the year (April-September v October-March), with seasons and quintiles of outdoor temperature as possible effect modifiers. There was a significant (p<0.001) interaction between PM10 and period of the year in relation to mortality. To allow for non-linearity, daily mean PM10 concentrations were categorised into quartiles. Season-specific PM10 quartiles showed a strong and steep linear association between mortality and PM10 in summer and a less linear association in spring and autumn, whereas in winter the association was less strong and mortality was only increased in the highest PM10 quartile. The effect sizes expressed as the percentage increase in mortality on days in the highest season-specific PM(10) quartile versus the lowest season-specific PM10 quartile were 7.8% (95% CI 6.1 to 9.6) in summer, 6.3% (4.7 to 7.8) in spring, 2.2% (0.58 to 3.8) in autumn and 1.4% (0.06 to 2.9) in winter. An analysis by quintiles of temperature confirmed these effect sizes. The short-term effect of particulate air pollution on mortality strongly depends on outdoor temperature, even in a temperate climate.
    Journal of Epidemiology &amp Community Health 03/2007; 61(2):146-9. · 3.39 Impact Factor
  • Epidemiology. 01/2006; 17.
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