Auflistung nach Autor:in "Schindler, Christian"

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Characterization of source-specific air pollution exposure for a large population-based Swiss cohort (SAPALDIA)
(National Institute of Environmental Health Sciences, 2007) Liu, L.-J. Sally; Curjuric, Ivan; Keidel, Dirk; Heldstab, Jürg; Künzli, Nino; Bayer-Oglesby, Lucy; Ackermann-Liebrich, Ursula; Schindler, Christian
Background: Although the dispersion model approach has been used in some epidemiologic studies to examine health effects of traffic-specific air pollution, no study has evaluated the model predictions vigorously. Methods: We evaluated total and traffic-specific particulate matter < 10 and < 2.5 microm in aero-dynamic diameter (PM(10), PM(2.5)), nitrogren dioxide, and nitrogen oxide concentrations predicted by Gaussian dispersion models against fixed-site measurements at different locations, including traffic-impacted, urban-background, and alpine settings between and across cities. The model predictions were then used to estimate individual subjects' historical and cumulative exposures with a temporal trend model. Results: Modeled PM(10) and NO(2) predicted at least 55% and 72% of the variability of the measured PM(10) and NO(2), respectively. Traffic-specific pollution estimates correlated with the NO(x) measurements (R(2) >or=0.77) for background sites but not for traffic sites. Regional background PM(10) accounted for most PM(10) mass in all cities. Whereas traffic PM(10) accounted for < 20% of the total PM(10), it varied significantly within cities. The modeling error for PM(10) was similar within and between cities. Traffic NO(x) accounted for the majority of NO(x) mass in urban areas, whereas background NO(x) accounted for the majority of NO(x) in rural areas. The within-city NO(2) modeling error was larger than that between cities. Conclusions: The dispersion model predicted well the total PM(10), NO(x), and NO(2) and traffic-specific pollution at background sites. However, the model underpredicted traffic NO(x) and NO(2) at traffic sites and needs refinement to reflect local conditions. The dispersion model predictions for PM(10) are suitable for examining individual exposures and health effects within and between cities.
01A - Beitrag in wissenschaftlicher Zeitschrift
Decline of Ambient Air Pollution Levels and Improved Respiratory Health in Swiss Children
(National Institute of Environmental Health Sciences, 11/2005) Bayer-Oglesby, Lucy; Grize, Leticia; Gassner, Markus; Takken-Sahli, Kathy; Sennhauser, Felix H.; Neu, Urs; Schindler, Christian; Braun-Fahrländer, Charlotte
The causality of observed associations between air pollution and respiratory health in children is still subject to debate. If reduced air pollution exposure resulted in improved respiratory health of children, this would argue in favor of a causal relation. We investigated whether a rather moderate decline of air pollution levels in the 1990s in Switzerland was associated with a reduction in respiratory symptoms and diseases in school children. In nine Swiss communities, 9,591 children participated in cross-sectional health assessments between 1992 and 2001. Their parents completed identical questionnaires on health status and covariates. We assigned to each child an estimate of regional particles with an aerodynamic diameter < 10 μg/m3 (PM10) and determined change in PM10 since the first survey. Adjusted for socioeconomic, health-related, and indoor factors, declining PM10 was associated in logistic regression models with declining prevalence of chronic cough [odds ratio (OR) per 10-μg/m3 decline = 0.65, 95% confidence interval (CI), 0.54–0.79], bronchitis (OR = 0.66; 95% CI, 0.55–0.80), common cold (OR = 0.78; 95% CI, 0.68–0.89), nocturnal dry cough (OR = 0.70; 95% CI, 0.60–0.83), and conjunctivitis symptoms (OR = 0.81; 95% CI, 0.70–0.95). Changes in prevalence of sneezing during pollen season, asthma, and hay fever were not associated with the PM10 reduction. Our findings show that the reduction of air pollution exposures contributes to improved respiratory health in children. No threshold of adverse effects of PM10 was apparent because we observed the beneficial effects for relatively small changes of rather moderate air pollution levels. Current air pollution levels in Switzerland still exceed limit values of the Swiss Clean Air Act; thus, children’s health can be improved further.
01A - Beitrag in wissenschaftlicher Zeitschrift
Follow-up of the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA 2) 1991–2003: methods and characterization of participants
(Birkhäuser, 2005) Ackermann-Liebrich, Ursula; Kuna-Dibbert, Birgit; Probst-Hensch, Nicole M.; Schindler, Christian; Dietrich, Denise Felber; Stutz, Elisabeth Zemp; Bayer-Oglesby, Lucy; Baum, Felix; Brändli, Otto; Brutsche, Martin; Downs, Sara H.; Keidel, Dirk; Gerbase, Margaret W.; Imboden, Medea; Keller, Roland; Knöpfli, Bruno; Künzli, Nino; Nicod, Laurent; Pons, Marco; Staedele, Patricia; Tschopp, Jean-Marie; Zellweger, Jean-Pierre; Leuenberger, Philippe
Objectives: The Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) was designed to investigate the health effects from long-term exposure to air pollution. Methods: The health assessment at recruitment (1991) and at the first reassessment (2001-3) consisted of an interview about respiratory health, occupational and other exposures, spirometry, a methacholine bronchial challenge test, end-expiratory carbon monoxide (CO) measurement and measurement for atopy. A bio bank for DNA and blood markers was established. Heart rate variability was measured using a 24-hour ECG (Holter) in a random sample of participants aged 50 years and older. Concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3) and particulates in ambient air have been monitored in all study areas since 1991. Residential histories collected over the 11 year follow-up period coupled with GIS modelling will provide individual long-term air pollutant exposure estimates. Results: Of 9651 participants examined in 1991, 8715 could be traced for the cohort study and 283 died. Basic information about health status was obtained for 8047 individuals (86% of alive persons), 6 528 individuals (70%) agreed to the health examination and 5 973 subjects (62%) completed the entire protocol. Non-participants in the reassessment were on average younger than participants and more likely to have been smokers and to have reported respiratory symptoms in the first assessment. Average weight had increased by 5.5 kg in 11 years and 28% of smokers in 1991 had quit by the time of the reassessment.
01A - Beitrag in wissenschaftlicher Zeitschrift
Improvements in PM10 Exposure and Reduced Rates of Respiratory Symptoms in a Cohort of Swiss Adults (SAPALDIA)
(American Thoracic Society, 2009) Schindler, Christian; Keidel, Dirk; Gerbase, Margaret W.; Zemp, Elisabeth; Bettschart, Robert; Brändli, Otto; Brutsche, Martin H.; Burdet, Luc; Karrer, Werner; Knöpfli, Bruno; Pons, Marco; Rapp, Regula; Bayer-Oglesby, Lucy; Künzli, Nino; Schwartz, Joel; Liu, Lee-Jane S.; Ackermann-Liebrich, Ursula; Rochat, Thierry
Rationale: Reductions in mortality following improvements in air quality were documented by several studies, and our group found, in an earlier analysis, that decreasing particulate levels attenuate lung function decline in adults. Objectives: We investigated whether decreases in particulates with an aerodynamic diameter of less than 10 microm (PM10) were associated with lower rates of reporting respiratory symptoms (i.e., decreased morbidity) on follow-up. Methods: The present analysis includes 7,019 subjects who underwent detailed baseline examinations in 1991 and a follow-up interview in 2002. Each subject was assigned model-based estimates of average PM10 during the 12 months preceding each health assessment and the difference was used as the exposure variable of interest (DeltaPM10). Analyses were stratified by symptom status at baseline and associations between DeltaPM10 and change in symptom status during follow-up were adjusted for important baseline characteristics, smoking status at follow-up, and season. We then estimated adjusted odds ratios for symptoms at follow-up and numbers of symptomatic cases prevented due to the observed reductions in PM10. Measurements and main results: Residential exposure to PM10 was lower in 2002 than in 1991 (mean decline 6.2 microg/m3; SD = 3.9 microg/m3). Estimated benefits (per 10,000 persons) attributable to the observed changes in PM10-levels were: 259 (95% confidence interval [CI]: 102-416) fewer subjects with regular cough, 179 (95% CI, 30-328) fewer subjects with chronic cough or phlegm and 137 (95% CI, 9-266) fewer subjects with wheezing and breathlessness. Conclusions: Reductions in particle levels in Switzerland over the 11-year follow-up period had a beneficial effect on respiratory symptoms among adults.
01A - Beitrag in wissenschaftlicher Zeitschrift
Living near main streets and respiratory symptoms in adults. the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults
(Oxford University Press, 10.10.2006) Bayer-Oglesby, Lucy; Schindler, Christian; Hazenkamp-von Arx, Marianne E.; Braun-Fahrländer, Charlotte; Keidel, Dirk; Rapp, Regula; Künzli, Nino; Braendli, Otto; Burdet, Luc; Sally Liu, L-J; Leuenberger, Philippe; Ackermann-Liebrich, Ursula
The Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA), conducted in 1991 (SAPALDIA 1) in eight areas among 9,651 randomly selected adults aged 18-60 years, reported associations among the prevalence of respiratory symptoms, nitrogen dioxide, and particles with an aerodynamic diameter of less than 10 microg/m3. Later, 8,047 subjects reenrolled in 2002 (SAPALDIA 2). The effects of individually assigned traffic exposures on reported respiratory symptoms were estimated, while controlling for socioeconomic and exposure- and health-related factors. The risk of attacks of breathlessness increased for all subjects by 13% (95% confidence interval: 3, 24) per 500-m increment in the length of main street segments within 200 m of the home and decreased in never smokers by 12% (95% confidence interval: 0, 22) per 100-m increment in distance from home to a main street. Living within 20 m of a main street increased the risks of regular phlegm by 15% (95% confidence interval: 0, 31) and wheezing with breathing problems by 34% (95% confidence interval: 0, 79) in never smokers. In 2002, the effects related to road distance were different from those in 1991, which could be due to changes in the traffic pollution mixture. These findings among a general population provide strong confirmation that living near busy streets leads to adverse respiratory health effects.
01A - Beitrag in wissenschaftlicher Zeitschrift
Long-term exposure models for traffic related NO2 across geographically diverse areas over separate years
(Elsevier, 2012) Sally Liu, L.-J.; Tsai, Ming-Yi; Keidel, Dirk; Gemperli, Armin; Ineichen, Alex; Hazenkamp-von Arx, Marianne; Bayer-Oglesby, Lucy; Rochat, Thierry; Künzli, Nino; Ackermann-Liebrich, Ursula; Straehl, Peter; Schwartz, Joel; Schindler, Christian
Although recent air pollution epidemiologic studies have embraced land-use regression models for estimating outdoor traffic exposure, few have examined the spatio-temporal variability of traffic related pollution over a long term period and the optimal methods to take these factors into account for exposure estimates. We used home outdoor NO2 measurements taken from eight geographically diverse areas to examine spatio-temporal variations, construct, and evaluate models that could best predict the within-city contrasts in observations. Passive NO2 measurements were taken outside of up to 100 residences per area over three seasons in 1993 and 2003 as part of the Swiss cohort study on air pollution and lung and heart disease in adults (SAPALDIA). The spatio-temporal variation of NO2 differed by area and year. Regression models constructed using the annual NO2 means from central monitoring stations and geographic parameters predicted home outdoor NO2 levels better than a dispersion model. However, both the regression and dispersion models underestimated the within-city contrasts of NO2 levels. Our results indicated that the best models should be constructed for individual areas and years, and would use the dispersion estimates as the urban background, geographic information system (GIS) parameters to enhance local characteristics, and temporal and meteorological variables to capture changing local dynamics. Such models would be powerful tools for assessing health effects from long-term exposure to air pollution in a large cohort
01A - Beitrag in wissenschaftlicher Zeitschrift
Long-term Source-Specific Air Pollution Exposure Characterization for a Large Population-Based Swiss Cohort (SAPALDIA)
(Lippincott Williams & Wilkins, 2006) Liu, Lee-Jane Sally; Curjuric, Ivan; Hazenkamp, Marianne; Keidel, Dirk; Bayer-Oglesby, Lucy; Ackermann-Liebrich, Ursula; Schindler, Christian
Although evidence on acute health effects related to traffic exhaust is accumulating, there is less information regarding long-term exposure of source-specific air pollution in the general population. The SAPALDIA study is a long-term air pollution study that included 7990 subjects from 8 areas in Switzerland with the first health examination in 1991 and the second examination in 2002. Each area was monitored with up to 3 monitoring sites for PM, NO2, and other gaseous pollutants. In 1999–2000, a sampling campaign was conducted for PM10, PM2.5, and black smoke at 16 Swiss sites. In 2002–2003, passive NO2 measurements were collected strategically over the year outside and inside approximately 60 homes per area. Annual average concentrations of source-specific and total PM2.5, PM10, and NOx were estimated using a Gaussian dispersion model with GIS to match individual residences of the SAPALDIA subjects. This paper examines the performance of the dispersion model, variation of source-specific air pollution exposures, and the implications of these findings to long-term air pollution epidemiologic studies. For PM10 in 2000, modeled values predicted 68% of the variability in the measurements. For NO2 in 2000, the model predicted the measured values with an R2 over 0.80. The R2 for traffic-specific pollutant predictions ranged between 0.44 (P = 0.08) for traffic-related PM2.5 and 0.81 (P < 0.01) for traffic-related NO2 for sites with low traffic impacts. However, when traffic sites were included in the comparisons, the R2 was lower, ranging between 0.41 for traffic-originated PM10 and 0.51 for traffic-originated NO2. Nevertheless, our preliminary results indicated that variance in traffic-originated pollutants accounted for up to 45% of the variance in total PM10, 69% of that in total PM2.5, and 91% of that in NOx. In addition, we smoothed actual NO2 measurements outside individual residences and correlated the resulting smoothed estimates at these sites with NO2 estimates from the dispersion model. To obtain good agreement between the measured and modeled surfaces (r > 0.60), the minimal spatial smoothing window was found to range between 200 m in rural Davos and 1.75 km for urban Basel. Our results indicate that sites affected largely by regional and urban background pollution are properly presented by the model. Locations impacted by local traffic, however, may not be adequately predicted by the model and need either fine-tuning of the model or additional parameters to reflect local conditions. Predictions of exposures to source-specific air pollution are being examined against a series of respiratory and cardiovascular health effects in other papers.
01A - Beitrag in wissenschaftlicher Zeitschrift
Reduced exposure to PM10 and attenuated age-related decline in lung function
(Massachusetts Medical Society, 2007) Downs, Sara H.; Schindler, Christian; Liu, L.-J. Sally; Keidel, Dirk; Bayer-Oglesby, Lucy; Brutsche, Martin H.; Gerbase, Margaret W.; Keller, Roland; Künzli, Nino; Leuenberger, Philippe; Probst-Hensch, Nicole M.; Tschopp, Jean-Marie; Zellweger, Jean-Pierre; Rochat, Thierry; Schwartz, Joel; Ackermann-Liebrich, Ursula
Background: Air pollution has been associated with impaired health, including reduced lung function in adults. Moving to cleaner areas has been shown to attenuate adverse effects of air pollution on lung function in children but not in adults. Methods: We conducted a prospective study of 9651 adults (18 to 60 years of age) randomly selected from population registries in 1990 and assessed in 1991, with 8047 participants reassessed in 2002. There was complete information on lung volumes and flows (e.g., forced vital capacity [FVC], forced expiratory volume in 1 second [FEV1], FEV1 as a percentage of FVC, and forced expiratory flow between 25 and 75% of the FVC [FEF25–75]), smoking habits, and spatially resolved concentrations of particulate matter that was less than 10 μm in aerodynamic diameter (PM10) from a validated dispersion model assigned to residential addresses for 4742 participants at both the 1991 and the 2002 assessments and in the intervening years. Results: Overall exposure to individual home outdoor PM10 declined over the 11-year follow-up period (median, −5.3 μg per cubic meter; interquartile range, −7.5 to −4.2). In mixed-model regression analyses, with adjustment for confounders, PM10 concentrations at baseline, and clustering within areas, there were significant negative associations between the decrease in PM10 and the rate of decline in FEV1 (P=0.045), FEV1 as a percentage of FVC (P=0.02), and FEF25–75 (P=0.001). The net effect of a decline of 10 μg of PM10 per cubic meter over an 11-year period was to reduce the annual rate of decline in FEV1 by 9% and of FEF25–75 by 16%. Cumulative exposure in the interval between the two examinations showed similar associations. Conclusions: Decreasing exposure to airborne particulates appears to attenuate the decline in lung function related to exposure to PM10. The effects are greater in tests reflecting small-airway function.
01A - Beitrag in wissenschaftlicher Zeitschrift
Relationship of aerobic fitness and motor skills with memory and attention in preschoolers (Ballabeina): A cross-sectional and longitudinal study
(BioMed Central, 2011) Niederer, Iris; Kriemler, Susi; Gut, Janine; Hartmann, Tim; Schindler, Christian; Barral, Jérôme; Puder, Jardena J.
01A - Beitrag in wissenschaftlicher Zeitschrift
Single pollutant versus surrogate measure approaches: Do single pollutant risk assessments underestimate the impact of air pollution on lung cancer risk?
(Lippincott Williams & Wilkins, 2003) Röösli, Martin; Künzli, Nino; Schindler, Christian; Theis, Gaston; Bayer-Oglesby, Lucy; Mathys, Patrick; Camenzind, Markus; Braun-Fahrländer, Charlotte
Cancer risk as a result of air pollution may be quantified by different approaches. We compared the sum of unit risk based effects of single pollutants with an epidemiology-based method by using PM10 as a surrogate of the total air pollution. The excess rate for lung cancer cases attributable to an increase of 10 μg/m3 in average PM10 exposure was estimated from available cohort studies. Applying the epidemiology-based risk method to the air pollution situation in the Basel area (Switzerland) resulted in 13.3 (95% CI = 6.9–19.8) excess lung cancer cases per 100,000 person years. This estimate was considerably higher than the unit risk-based estimate yielding 1.1 (range, 0.45–2.8) cancer cases per 100,000 person years. We discuss these discrepancies in light of inherent differences between approaches in toxicology and epidemiology.
01A - Beitrag in wissenschaftlicher Zeitschrift
Validity of Annoyance Scores for Estimation of Long Term Air Pollution Exposure in Epidemiologic Studies. The Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA)
(Oxford University Press, 01.07.2000) Bayer-Oglesby, Lucy; Künzli, Nino; Monn, Christian; Schindler, Christian; Ackermann-Liebrich, Ursula; Leuenberger, Philippe
In air pollution epidemiology, estimates of long term exposure are often based on measurements made at one fixed site monitor per area. This may lead to exposure misclassification. The present paper validates a questionnaire-based indicator of ambient air pollution levels and its applicability to assess their within-area variability. Within the framework of the SAPALDIA (Swiss Study on Air Pollution and Lung Diseases in Adults) cross-sectional study (1991), 9,651 participants reported their level of annoyance caused by air pollution on an 11-point scale. This subjective measure was compared with annual mean concentrations of particulate matter less than 10 μm in diameter (PM10) and nitrogen dioxide. The impact of individual factors on reported scores was evaluated. Nitrogen dioxide concentrations at home outdoors (measured in 1993), smoking, workplace dust exposure, and respiratory symptoms were found to be predictors of individual annoyance scores. Regression of population mean annoyance scores against annual mean PM10 and nitrogen dioxide concentrations (measured in 1993 and 1991, respectively) across areas showed a linear relation and strong correlations (r > 0.85). Analysis within areas yielded consistent results. The observed associations between subjective and objective air pollution exposure estimates suggest that population mean scores, but not individual scores, may serve as a simple tool for grading air quality within areas. Reported annoyance due to air pollution should be considered an indicator for a complex environmental condition and thus might be used for evaluating the implementation of environmental policies.
01A - Beitrag in wissenschaftlicher Zeitschrift