Publications by authors named "Uwe Schlink"

26 Publications

  • Page 1 of 1

Perspectives of individual-worn sensors assessing personal environmental exposure.

Engineering (Beijing) 2020 Oct 22. Epub 2020 Oct 22.

Department of Urban and Environmental Sociology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.

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http://dx.doi.org/10.1016/j.eng.2020.07.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7577893PMC
October 2020

Impact of urban heat island on meteorology and air quality at microenvironments.

J Air Waste Manag Assoc 2020 09 20;70(9):876-891. Epub 2020 Jul 20.

Department Urban and Environmental Sociology, Helmholtz Centre for Environmental Research-UFZ , Leipzig, Germany.

This study analyzes the air pollution characteristics and their relation to meteorological conditions in Chennai, India. Meteorological conditions were the primary factor determining variations in daily average pollutant concentrations. The influence of urban infrastructure on meteorology is an important prediction on air quality. Understanding of the seasonal and diurnal secondary pollutant concentrations as a function of local meteorological conditions is necessary for urban air quality management. Micro-scale models for analyzing the surface layer interactions with the surrounding environment have recently gained attention. An attempt has been made to understand the effect of meteorology on air quality. This comprehensive study aims to assess the influence of local meteorology on urban air quality. The correlation was established between the change in meteorological parameters and mixing height on air quality at selected locations in a tropical urban environment. Results indicated the significant impact of land use patterns on the dispersion of air quality at study locations. Seasonal variations of ambient air temperatures at study locations were found to be more than 3°C in summer. Average mixing height variation among the study locations was observed to be more than 200 meters in summer. Results indicated the importance of wind velocity on the mixing height at study locations. The average concentrations of air quality parameters showed significant variation among the study locations. The maximum ozone (O) concentration was recorded at the Central Business District (CBD) during the afternoon, i.e., around 38.3 ppb, whereas it was 26.8 and 14.6 ppb at the Residential Area (RA) and Urban Baseline (UBL), respectively. A strong correlation was observed between ambient temperature and O concentration during summer. In the winter, the average O concentration in all three-study locations increased to 45.3 ppb, 45.8 ppb, and 58.5 ppb at UBL, RA, and CBD sites, respectively. The study reveals the impact of microenvironments on air quality. : An attempt has been made to study the seasonal and diurnal variation of air quality levels in selected study regions with land cover change. This article focuses mainly on the surface temperature intensity variations with respect to the percentage of land use pattern change in Chennai city, India, and the subsequent effect on meteorology of dispersion conditions and air quality parameters has been studied. The relationship between local meteorology and air quality has been established.
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http://dx.doi.org/10.1080/10962247.2020.1783390DOI Listing
September 2020

How to convert urban energy balance into contributions to urban excess temperatures?

MethodsX 2019 27;6:132-142. Epub 2018 Dec 27.

Department of Urban and Environmental Sociology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, D-04318, Leipzig, Germany.

A new approach partitioning the urban heat island intensity (ΔT) into its contributing processes is developed for the neighbourhood scale. The method transforms individual terms of the energy balance (radiation, evapotranspiration, heat storage, and convection) into partitions of temperature and is exemplified using the output of a micrometeorological model. •The temperature contribution is determined by climate sensitivity and a gain function depending on the energy redistribution factor.•The method is exemplified for the output of ENVI-met.•The software implementing the method is written in R language, a free language enabling statistical computations.
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http://dx.doi.org/10.1016/j.mex.2018.12.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6330375PMC
December 2018

Wearable sensors for multifactorial personal exposure measurements - A ranking study.

Environ Int 2018 12 8;121(Pt 1):130-138. Epub 2018 Sep 8.

Department of Urban and Environmental Sociology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.

Individuals are simultaneously exposed to multiple environmental stressors during their daily life. Studies of adverse health effects and their etiology as well as recommendations for a healthier life style demand for an assessment of multifactorial personal exposure, according to the exposome concept. A challenge is to record exposure while people are moving in heterogeneous urban environments. Therefore wearable sensor technologies are becoming a promising way to measure personal exposure continuously: indoors, outdoors and even on the move. So far, studies which test the accuracy and usability of wearable sensors for multiple stressors are lacking. Performance evaluations are important and should take place beforehand, especially to ensure the success of citizens-oriented studies. For the first time we rigorously examined the accuracy and application suitability of wearable sensors for acoustic noise, heat (temp), particle number counts (PNC) and geo-location (GPS) in different environments. We present an extensive device inter-comparison and a ranking of the sensors based on performance measures, Taylor diagrams, Bland-Altman plots, and ease-of-use aspects. The sensors showed moderate to high correlations with precision reference devices (r = 0.4-0.99). Differences between errors outdoors and indoors suggest that environmental conditions have impact upon the accuracy of the sensors. Reaction time, recording interval, and sensor ventilation are features that play a crucial role for both ease-of-use and accuracy. We conclude with a final performance () ranking: (GPS) >  (noise) >  (temp) >  (PNC). The results are relevant for future epidemiological studies of multifactorial exposure of individuals and their health and should guide the selection of wearables when persons are involved that are technically untaught. Inferences from multifactorial data are based on the performance of all sensors and the weakest chain links are PNC and temp sensors for which our article recommends urgent improvements.
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http://dx.doi.org/10.1016/j.envint.2018.08.057DOI Listing
December 2018

Advanced Smartphone-Based Sensing with Open-Source Task Automation.

Sensors (Basel) 2018 Jul 29;18(8). Epub 2018 Jul 29.

Department of Urban and Environmental Sociology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany.

Smartphone-based sensing is becoming a convenient way to collect data in science, especially in environmental research. Recent studies that use smartphone sensing methods focus predominantly on single sensors that provide quantitative measurements. However, interdisciplinary projects call for study designs that connect both, quantitative and qualitative data gathered by smartphone sensors. Therefore, we present a novel open-source task automation solution and its evaluation in a personal exposure study with cyclists. We designed an automation script that advances the sensing process with regard to data collection, management and storage of acoustic noise, geolocation, light level, timestamp, and qualitative user perception. The benefits of this approach are highlighted based on data visualization and user handling evaluation. Even though the automation script is limited by the technical features of the smartphone and the quality of the sensor data, we conclude that task automation is a reliable and smart solution to integrate passive and active smartphone sensing methods that involve data processing and transfer. Such an application is a smart tool gathering data in population studies.
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http://dx.doi.org/10.3390/s18082456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6111588PMC
July 2018

Urban heat island (UHI) influence on secondary pollutant formation in a tropical humid environment.

J Air Waste Manag Assoc 2017 10 16;67(10):1080-1091. Epub 2017 May 16.

b Department of Urban and Environmental Sociology , Helmholtz Center for Environmental Research-UFZ , Leipzig , Germany.

The combined action of urbanization (change in land use) and increase in vehicular emissions intensifies the urban heat island (UHI) effect in many cities in the developed countries. The urban warming (UHI) enhances heat-stress-related diseases and ozone (O) levels due to a photochemical reaction. Even though UHI intensity depends on wind speed, wind direction, and solar flux, the thermodynamic properties of surface materials can accelerate the temperature profiles at the local scale. This mechanism modifies the atmospheric boundary layer (ABL) structure and mixing height in urban regions. These changes further deteriorate the local air quality. In this work, an attempt has been made to understand the interrelationship between air pollution and UHI intensity at selected urban areas located at tropical environment. The characteristics of ambient temperature profiles associated with land use changes in the different microenvironments of Chennai city were simulated using the Envi-Met model. The simulated surface 24-hr average air temperatures (11 m above the ground) for urban background and commercial and residential sites were found to be 30.81 ± 2.06, 31.51 ± 1.87, and 31.33 ± 2.1ºC, respectively. The diurnal variation of UHI intensity was determined by comparing the daytime average air temperatures to the diurnal air temperature for different wind velocity conditions. From the model simulations, we found that wind speed of 0.2 to 5 m/sec aggravates the UHI intensity. Further, the diurnal variation of mixing height was also estimated at the study locations. The estimated lowest mixing height at the residential area was found to be 60 m in the middle of night. During the same period, highest ozone (O) concentrations were also recorded at the continuous ambient air quality monitoring station (CAAQMS) located at the residential area.

Implications: An attempt has made to study the diurnal variation of secondary pollution levels in different study regions. This paper focuses mainly on the UHI intensity variations with respect to percentage of land use pattern change in Chennai city, India. The study simulated the area-based land use pattern with local mixing height variations. The relationship between UHI intensity and mixing height provides variations on local air quality.
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http://dx.doi.org/10.1080/10962247.2017.1325417DOI Listing
October 2017

Degradation of indoor limonene by outdoor ozone: A cascade of secondary organic aerosols.

Environ Pollut 2017 Jul 27;226:463-472. Epub 2017 Apr 27.

Department Urban and Environmental Sociology, UFZ Helmholtz Centre for Environmental Research, Permoserstrasse 15, 04318 Leipzig, Germany. Electronic address:

In indoor air, terpene-ozone reactions can form secondary organic aerosols (SOA) in a transient process. 'Real world' measurements conducted in a furnished room without air conditioning were modelled involving the indoor background of airborne particulate matter, outdoor ozone infiltrated by natural ventilation, repeated transient limonene evaporations, and different subsequent ventilation regimes. For the given setup, we disentangled the development of nucleated, coagulated, and condensed SOA fractions in the indoor air and calculated the time dependence of the aerosol mass fraction (AMF) by means of a process model. The AMF varied significantly between 0.3 and 5.0 and was influenced by the ozone limonene ratio and the background particles which existed prior to SOA formation. Both influencing factors determine whether nucleation or adsorption processes are preferred; condensation is strongly intensified by particulate background. The results provide evidence that SOA levels in natural indoor environments can surpass those known from chamber measurements. An indicator for the SOA forming potential of limonene was found to be limona ketone. Multiplying its concentration (in μg/m) by 450(±100) provides an estimate of the concentration of the reacted limonene. This can be used to detect a high particle formation potential due to limonene pollution, e.g. in epidemiological studies considering adverse health effects of indoor air pollutants.
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http://dx.doi.org/10.1016/j.envpol.2017.04.030DOI Listing
July 2017

Integrating modelling and smart sensors for environmental and human health.

Environ Model Softw 2015 Dec;74:238-246

Geospatial Sciences Center of Excellence, South Dakota State University, Brookings, SD 57007-3510, USA.

Sensors are becoming ubiquitous in everyday life, generating data at an unprecedented rate and scale. However, models that assess impacts of human activities on environmental and human health, have typically been developed in contexts where data scarcity is the norm. Models are essential tools to understand processes, identify relationships, associations and causality, formalize stakeholder mental models, and to quantify the effects of prevention and interventions. They can help to explain data, as well as inform the deployment and location of sensors by identifying hotspots and areas of interest where data collection may achieve the best results. We identify a paradigm shift in how the integration of models and sensors can contribute to harnessing 'Big Data' and, more importantly, make the vital step from 'Big Data' to 'Big Information'. In this paper, we illustrate current developments and identify key research needs using human and environmental health challenges as an example.
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http://dx.doi.org/10.1016/j.envsoft.2015.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4669571PMC
December 2015

The lasting effect of limonene-induced particle formation on air quality in a genuine indoor environment.

Environ Sci Pollut Res Int 2015 Sep 14;22(18):14209-19. Epub 2015 May 14.

Department of Urban and Environmental Sociology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318, Leipzig, Germany,

Atmospheric ozone-terpene reactions, which form secondary organic aerosol (SOA) particles, can affect indoor air quality when outdoor air mixes with indoor air during ventilation. This study, conducted in Leipzig, Germany, focused on limonene-induced particle formation in a genuine indoor environment (24 m(3)). Particle number, limonene and ozone concentrations were monitored during the whole experimental period. After manual ventilation for 30 min, during which indoor ozone levels reached up to 22.7 ppb, limonene was introduced into the room at concentrations of approximately 180 to 250 μg m(-3). We observed strong particle formation and growth within a diameter range of 9 to 50 nm under real-room conditions. Larger particles with diameters above 100 nm were less affected by limonene introduction. The total particle number concentrations (TPNCs) after limonene introduction clearly exceed outdoor values by a factor of 4.5 to 41 reaching maximum concentrations of up to 267,000 particles cm(-3). The formation strength was influenced by background particles, which attenuated the formation of new SOA with increasing concentration, and by ozone levels, an increase of which by 10 ppb will result in a six times higher TPNC. This study emphasizes indoor environments to be preferred locations for particle formation and growth after ventilation events. As a consequence, SOA formation can produce significantly higher amounts of particles than transported by ventilation into the indoor air.
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http://dx.doi.org/10.1007/s11356-015-4663-8DOI Listing
September 2015

Size-fractioned particulate air pollution and cardiovascular emergency room visits in Beijing, China.

Environ Res 2013 Feb 30;121:52-63. Epub 2013 Jan 30.

Helmholtz Zentrum München-German Research Center for Environmental Health, Institute of Epidemiology II, Neuherberg, Germany.

Background: Although short-term exposure to ambient particulate matter has increasingly been linked with cardiovascular diseases, it is not quite clear how physical characteristics of particles, such as particle size may be responsible for the association. This study aimed at investigating whether daily changes in number or mass concentrations of accurately size-segregated particles in the range of 3nm-10μm are associated with daily cardiovascular emergency room visits in Beijing, China.

Methods: Cardiovascular emergency room visit counts, particle size distribution data, and meteorological data were collected from Mar. 2004 to Dec. 2006. Particle size distribution data was used to calculate particle number concentration in different size fractions, which were then converted to particle mass concentration assuming spherical particles. We applied a time-series analysis approach. We evaluated lagged associations between cardiovascular emergency room visits and particulate number and mass concentration using distributed lag non-linear models up to lag 10. We calculated percentage changes of cardiovascular emergency room visits, together with 95% confidence intervals (CI), in association with an interquartile range (IQR, difference between the third and first quartile) increase of 11-day or 2-day moving average number or mass concentration of particulate matter within each size fraction, assuming linear effects. We put interaction terms between season and 11-day or 2-day average particulate concentration in the models to estimate the modification of the particle effects by season.

Results: We observed delayed associations between number concentration of ultrafine particles and cardiovascular emergency room visits, mainly from lag 4 to lag 10, mostly contributed by 10-30nm and 30-50nm particles. An IQR (9040cm(-3)) increase in 11-day average number concentration of ultrafine particles was associated with a 7.2% (1.1-13.7%) increase in total, and a 7.9% (0.5-15.9%) increase in severe cardiovascular emergency room visits. The delayed effects of particulate mass concentration were small. Regarding immediate effects, 2-day average number concentration of Aitken mode (30-100nm) particles had strongest effects. An IQR (2269cm(-3)) increase in 2-day average number concentration of 30-50nm particles led to a 2.4% (-1.5-6.5%) increase in total, and a 1.7% (-2.9-6.5%) increase in severe cardiovascular emergency room visits. The immediate effects of mass concentration came mainly from 1000-2500nm particles. An IQR (11.7μgm(-3)) increase in 2-day average mass concentration of 1000-2500nm particles led to an around 2.4% (0.4-4.4%) increase in total, and a 1.7% (-0.8-4.2%) increase in severe cardiovascular emergency room visits. The lagged effect curves of number and mass concentrations of 100-300nm particles or 300-1000nm particles were quite similar, indicating that using particulate number or mass concentrations seemed not to affect the cardiovascular effect (of particles within one size fraction). The effects of number concentration of ultrafine particles, sub-micrometer particles (3-1000nm) and 10-30nm particles were substantially higher in winter comparing with in summer.

Conclusions: Elevated concentration levels of sub-micrometer particles were associated with increased cardiovascular morbidity. Ultrafine particles showed delayed effects, while accumulation mode (100-1000nm) particles showed immediate effects. Using number or mass concentrations did not affect the particle effects.
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http://dx.doi.org/10.1016/j.envres.2012.10.009DOI Listing
February 2013

Genetic association between obstructive bronchitis and enzymes of oxidative stress.

Metabolism 2012 Dec 26;61(12):1771-9. Epub 2012 Jun 26.

UFZ-Helmholtz Centre for Environmental Research, Department of Environmental Immunology, Leipzig, Germany.

Objective: Obstructive respiratory diseases, mainly the chronic obstructive pulmonary disease (COPD) and asthma, are associated with functional polymorphisms of xenobiotic-metabolizing enzymes (XMEs). To date, association for obstructive bronchitis has not been described.

Material/methods: In this study, we investigated the genotypes from 26 functional polymorphisms of 20 XMEs in children (n, 1028) at the age of 6 years from the German prospective birth cohort study (LISAplus) and analyzed the associations between genotypes and obstructive bronchitis.

Results: For the first time, we found noteworthy gene-disease associations for the functional PON1 M55L and EPHX1 H139R polymorphisms and gene-environment associations for the functional COMT V158M and NQO1 P187S polymorphisms after stratification for maternal active smoking behaviour during pregnancy. The noteworthy associations were substantiated by the biological findings that all the risk genotypes belong to genes involved in oxidative stress and code for proteins with a fast enzymatic activity or concomitantly appear in common estrogene-metabolizing pathway (COMT, NQO1).

Conclusion: The oxidative stress has to be taken into account in mechanism of the obstructive bronchitis in early childhood. The risk genotypes may serve as risk factors for respiratory obstruction rather than for signs of COPD or asthma.
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http://dx.doi.org/10.1016/j.metabol.2012.05.013DOI Listing
December 2012

Sub-micrometer particulate air pollution and cardiovascular mortality in Beijing, China.

Sci Total Environ 2011 Nov 21;409(24):5196-204. Epub 2011 Sep 21.

Helmholtz Zentrum München-German Research Center for Environmental Health, Institute of Epidemiology II, Neuherberg, Germany.

Background: While the link between particulate matter and cardiovascular mortality is well established, it is not fully investigated and understood which properties of the aerosol might be responsible for the health effects, especially in polluted mega-city areas.

Objectives: Our goal was to explore the association between daily cardiovascular mortality and different particle metrics in the sub-micrometer range in Beijing, China.

Methods: We obtained daily counts of cause-specific cardiovascular deaths in the Beijing urban area for the period March 2004 to August 2005. Concurrently, continuous measurements of particle number size distributions were performed. Particle number concentrations (NC) between 0.003 μm and 0.8 μm were converted to particle mass and surface area concentrations assuming spherical particles. Semi-parametric Poisson regression models adjusting for trend, seasonality, day of the week, and meteorology were used to estimate immediate, delayed and cumulative particle effects. Additionally, effect modification by air mass origin was investigated.

Results: We observed associations between daily cardiovascular mortality and particle NC for a 2-days delay. Moreover, nearly all particle metrics showed 2-days delayed associations with ischemic heart disease mortality. The strongest association was found for particle NC in the size range 0.03-0.1 μm (7.1% increase in daily mortality with a 95%-confidence interval of 2.9%-11.5%, per an increase of 6250 particles/cm3). Results for surface and mass concentrations with a lag of two days indicated effect modification by air mass origin, whereas effects of particle NC were not modified.

Conclusions: Results show an elevated risk of cardiovascular mortality in Beijing from short-term exposure to particulate air pollution in the sub-micrometer range. Results also indicate that locally produced smaller particles and regionally transported particles may exhibit different effects in Beijing.
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http://dx.doi.org/10.1016/j.scitotenv.2011.08.023DOI Listing
November 2011

Associations between size-segregated particle number concentrations and respiratory mortality in Beijing, China.

Int J Environ Health Res 2012 19;22(2):119-33. Epub 2011 Aug 19.

Helmholtz-Centre for Environmental Research (UFZ), Core Facility-Studies, Leipzig, Germany.

Numerous studies have described the adverse associations between particle mass and respiratory health. The aim of the study was to analyze the associations of particle properties, especially size-segregated particle number concentrations (PNC), and respiratory mortality in Beijing, P.R. China. We gathered daily values of respiratory mortality and air pollution data of the Beijing urban area. Generalized additive models were used to estimate the associations. Single pollutant models showed that delayed concentrations of SO(2), total PNCs, and PNC of 300-1000 nm were adversely associated with total respiratory mortality. There was an indication that adverse health effects of PNCs might be stronger for stagnant air masses. Two-pollutant models verified the independence of associations of total PNCs of other pollutants (SO(2), NO(2), and PM(10)). In conclusion, particle number concentrations, especially accumulation mode particles, might be factors influencing the adverse associations between particulate matter and respiratory health.
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http://dx.doi.org/10.1080/09603123.2011.605878DOI Listing
July 2012

Truncated Lévy flights and agenda-based mobility are useful for the assessment of personal human exposure.

Environ Pollut 2011 Aug-Sep;159(8-9):2061-70. Epub 2011 Mar 22.

Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany.

Receptor-oriented approaches can assess the individual-specific exposure to air pollution. In such an individual-based model we analyse the impact of human mobility to the personal exposure that is perceived by individuals simulated in an exemplified urban area. The mobility models comprise random walk (reference point mobility, RPM), truncated Lévy flights (TLF), and agenda-based walk (RPMA). We describe and review the general concepts and provide an inter-comparison of these concepts. Stationary and ergodic behaviour are explained and applied as well as performance criteria for a comparative evaluation of the investigated algorithms. We find that none of the studied algorithm results in purely random trajectories. TLF and RPMA prove to be suitable for human mobility modelling, because they provide conditions for very individual-specific trajectories and exposure. Suggesting these models we demonstrate the plausibility of their results for exposure to air-borne benzene and the combined exposure to benzene and nonane.
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http://dx.doi.org/10.1016/j.envpol.2011.02.023DOI Listing
September 2011

Respiratory effects of indoor particles in young children are size dependent.

Sci Total Environ 2011 Apr;409(9):1621-31

Helmholtz Centre for Environmental Research-UFZ, Core Facility Studies, Permoserstraße 15, 04318 Leipzig, Germany.

Background: Extensive epidemiological studies have provided evidence of an association between elevated outdoor particulate air pollution and adverse health effects. However, while people typically spend majority of time indoors, there is limited knowledge on airborne indoor particles and on the correlation between the concentrations of indoor particles and health effects. Even insights into the influence of differently sized indoor particles on human health are still rare.

Objective: The association between differentially sized indoor air particles and the development of respiratory diseases was studied for three year aged children.

Methods: Short-term measurements of particle mass and number concentrations were carried out in children's rooms. Information on possible particle sources (smoking habits, type of heating, and traffic) and respiratory outcomes were obtained from questionnaires. Measured indoor particle concentrations were correlated with possible sources of indoor particles and with respiratory health impacts.

Results: Daily smoking, smoking more than 5 cigarettes per day at home and traffic density in front of the window of children's room were found to be related to indoor exposure by particles of different diameters. High indoor particle exposures were associated with an increased risk for the development of obstructive bronchitis and in some extent of non-obstructive bronchitis. The strongest impact was observed for the mass concentration of particles <1 μm and the number concentration of particles >0.5 μm. The risk increases still remain significant if tested for stability changing the number of adjustment variables or omitting randomly selected cases, respectively.

Conclusion: Our results show significant associations between indoor particle concentrations and the risks for respiratory diseases in young children. The applied short-term measurements can help to assess the health risks of indoor particles with different sizes within epidemiological studies.
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http://dx.doi.org/10.1016/j.scitotenv.2011.01.001DOI Listing
April 2011

Size-segregated particle number concentrations and respiratory emergency room visits in Beijing, China.

Environ Health Perspect 2011 Apr 30;119(4):508-13. Epub 2010 Nov 30.

Core Facility Studies, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.

Background: The link between concentrations of particulate matter (PM) and respiratory morbidity has been investigated in numerous studies.

Objectives: The aim of this study was to analyze the role of different particle size fractions with respect to respiratory health in Beijing, China.

Methods: Data on particle size distributions from 3 nm to 1 µm; PM10 (PM ≤ 10 µm), nitrogen dioxide (NO(2)), and sulfur dioxide concentrations; and meteorologic variables were collected daily from March 2004 to December 2006. Concurrently, daily counts of emergency room visits (ERV) for respiratory diseases were obtained from the Peking University Third Hospital. We estimated pollutant effects in single- and two-pollutant generalized additive models, controlling for meteorologic and other time-varying covariates. Time-delayed associations were estimated using polynomial distributed lag, cumulative effects, and single lag models.

Results: Associations of respiratory ERV with NO(2) concentrations and 100-1,000 nm particle number or surface area concentrations were of similar magnitude-that is, approximately 5% increase in respiratory ERV with an interquartile range increase in air pollution concentration. In general, particles < 50 nm were not positively associated with ERV, whereas particles 50-100 nm were adversely associated with respiratory ERV, both being fractions of ultrafine particles. Effect estimates from two-pollutant models were most consistent for NO(2).

Conclusions: Present levels of air pollution in Beijing were adversely associated with respiratory ERV. NO(2) concentrations seemed to be a better surrogate for evaluating overall respiratory health effects of ambient air pollution than PM(10) or particle number concentrations in Beijing.
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http://dx.doi.org/10.1289/ehp.1002203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3080933PMC
April 2011

A rigorous small area modelling-study for the Helicobacter pylori epidemiology.

Sci Total Environ 2010 Aug 5;408(18):3931-42. Epub 2010 May 5.

Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, 04318 Leipzig, Germany.

This paper presents an investigation into spatial risk differences over small distances for the Helicobacter pylori infection in the city of Leipzig, Germany and two rural districts. A model, using Bayesian inference, was developed that adjusts the risk for individual-specific factors, and for spatial or individual over-dispersion, respectively. Additionally, the model takes into account conditional spatial autocorrelation. We found a significant positive association to the H. pylori infection risk for: "more than three children live in the household" (OR=2.4, p=0.001), "more persons live per sq.m than average" (OR=1.4, p=0.03), "home situated at main road" (OR=1.4, p=0.04) and "using well water" (OR=2.3, p=0.05). A protective effect was identified for "travelled to low prevalence region" (OR=0.4, p<0.0001) and "born in Germany" (OR=0.2, p<0.0001). Three administrative areas with significantly increased spatial risk were identified: one in the rural district and two in the city of Leipzig. The model explained 24.9% of the total deviance. Contrary to expectations, the largest part of deviance of the data was not explained by the identified significant risk factors, but by individual-specific heterogeneities. We conclude that further - so far not discussed - factors influence the risk and the spatial variation of the H.pylori infection. Furthermore, from the results we speculate about a possible impact of long-time air pollution and surface water.
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http://dx.doi.org/10.1016/j.scitotenv.2010.03.045DOI Listing
August 2010

Evaluation of human mobility models, for exposure to air pollutants.

Sci Total Environ 2010 Aug 24;408(18):3918-30. Epub 2010 Apr 24.

Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, 04318 Leipzig, Germany.

The subject of the present study is to find the best way of making a simulation model for the exposure assessment of mobile individuals. For that purpose we consider and apply several very different approaches to model movement patterns in a more or less random way and compare them in terms of the exposure resulting for the individuals. The models combine random movement with agenda-driven movement. We do not aim to involve all details of real conditions into the models, but explain and review the general concepts and provide an inter-comparison of these concepts. Stationary and ergodic behaviour are explained and applied as well as performance criteria for a comparative evaluation of the investigated algorithms. In particular, the present study investigates the exposure to air contaminants of persons moving in heterogeneously polluted urban areas by help of movement simulations. For that purpose we applied four different movement algorithms: Lévy-modulated correlated random walk (LMCRW), Potential field controlled walk (PTW), Reference point mobility model (RPM), and RPM with a pre-defined daily agenda of targets (RPMA). We find that none of the studied algorithm results in purely random trajectories. PTW and RPMA prove to be suitable for human mobility modelling, because they provide conditions for very individual-specific trajectories and exposure. Suggesting these models we demonstrate the plausibility of their results for exposure to air-borne benzene and the combined exposure to benzene and nonane. It appears however that inter-individual variation in the individual-specific short-term exposure diminishes with runtime and when long-term exposure is considered.
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http://dx.doi.org/10.1016/j.scitotenv.2010.03.018DOI Listing
August 2010

Quantile regression of indoor air concentrations of volatile organic compounds (VOC).

Sci Total Environ 2010 Aug 6;408(18):3840-51. Epub 2010 Jan 6.

Helmholtz Centre for Environmental Research UFZ, Leipzig, Germany.

There are many factors determining the concentration of volatile organic compounds (VOCs) in indoor air. On the basis of 601 population-based measurements we develop an explicit exposure model that includes factors, such as renovation, furniture, flat size, smoking, and education level of the occupants. As a novel method for the evaluation of concentrations of indoor air pollutants we use quantile regression, which has the advantages of robustness against non-Gaussian distributions (and outliers) and can adjust for unbalanced frequencies of observations. The applied bi- and multivariate quantile regressions provide (1) the VOC burden that is representative for the population of Leipzig, Germany, and (2) an inter-comparison of the effects of the studied factors and their levels. As a result, we find strong evidence for factors of general impact on most VOC components, such as the season, flooring, the type of the room, and the size of the apartment. Other impact factors are very specific to the VOC components. For example, wooden flooring (parquet) and new furniture increase the concentration of terpenes as well as the modifying factors high education and sampling in the child's room. Smokers ventilate their flats in an extent that in general reduces the VOC concentrations, except for benzene (contained in tobacco smoke), which is still higher in smoking than in non-smoking flats. Very often dampness is associated with an increased VOC burden in indoor air. An investigation of mixtures emphasises a high burden of co-occurring terpenes in very small and very large apartments.
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http://dx.doi.org/10.1016/j.scitotenv.2009.12.002DOI Listing
August 2010

Respiratory health, effects of ambient air pollution and its modification by air humidity in Drobeta-Turnu Severin, Romania.

Sci Total Environ 2009 Jun 16;407(13):4004-11. Epub 2009 Apr 16.

Core Facility Studien, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, Leipzig, Germany.

Background: Associations between ambient air pollution and respiratory health have been mainly reported for Western Europe and Northern America.

Objectives: Our goal was to investigate such associations among the population of Drobeta-Turnu Severin, Romania, a city in Central Eastern Europe (CEE), and to quantify their modification by air humidity. The latter is of increased interest for the current discussion about the potential effects of climate change on human health.

Methods: We investigated (study period: 23.01.2001-31.08.2002) the associations between chronic obstructive pulmonary disease (COPD), asthma and chronic bronchitis (CB) and total suspended particles (TSP), sulphur dioxide (SO(2)) and nitrogen dioxide (NO(2)). Generalized additive models (GAM) controlling for time patterns and weather effects were applied. Delayed effects up to seven days were analysed in single lag and polynomial distributed lag models (PDLMs).

Results: An increase of 10 microg/m(3) TSP was related to a 3.3% (95% CI: 0.3%-6.4%) and a 2.8% (95% CI: 0.1%-5.7%) increase for hospital admissions for chronic bronchitis with a lag of one and four days, respectively. The adverse effect of TSP on chronic bronchitis was reduced by higher humidity. An increase of 10 microg/m(3) SO(2) was related to a 6% (95% CI: 7%-25%) increase, with a two days lag, for hospital admissions for chronic bronchitis. We have not been able to identify a threshold, below which ambient TSP and SO(2) concentrations have no effect on hospital admissions for chronic bronchitis. We found adverse but nonsignificant influences of TSP, SO(2) and NO(2) on total respiratory hospital admissions, COPD and asthma and NO(2) on chronic bronchitis.

Conclusions: We conclude that in Drobeta-Turnu Severin CB is associated with TSP and mainly SO(2). Dry air aggravates the adverse effect of TSP.
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http://dx.doi.org/10.1016/j.scitotenv.2009.02.042DOI Listing
June 2009

Increased asthma and respiratory symptoms in children exposed to petrochemical pollution.

J Allergy Clin Immunol 2009 Mar 25;123(3):632-8. Epub 2008 Dec 25.

Instituto del Desarrollo de Investigaciones Pediátricas Prof Dr Fernando Viteri Hospital de Niños SM Ludovica, La Plata, Argentina.

Background: Epidemiologic studies show statistical associations between levels of air pollutants and respiratory outcomes.

Objective: We sought to determine the effects of exposure to petrochemical pollution on the respiratory health of children.

Methods: Children aged 6 to 12 years living close to the petrochemical plants in La Plata, Argentina (n = 282), were compared with those living in a region with exposure to heavy traffic (n = 270) or in 2 relatively nonpolluted areas (n = 639). Parents answered a validated questionnaire providing health and demographic data. A random sample (n = 181) had lung function measured. Particulate matter and outdoor and indoor volatile organic compound levels were measured during 4-week study periods and reported as overall means for each study area.

Results: Children living near the petrochemical plant had more asthma (24.8% vs 10.1% to 11.5%), more asthma exacerbations (6.7 vs 2.9-3.6 per year), more respiratory symptoms (current wheeze, dyspnea, nocturnal cough, and rhinitis), and lower lung function (>13% decrease in FEV(1) percent predicted) than those living in other regions. Length of residence in the area was a significant risk factor, but age, sex, body mass index, proximity to busy roads and other nonpetrochemical industries, length of breast-feeding, and socioeconomic and demographic characteristics of children or their families were not.

Conclusion: Exposure to particulate matter and volatile organic compounds arising from petrochemical plants but not from high traffic density was associated ith worse respiratory health in children.
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http://dx.doi.org/10.1016/j.jaci.2008.09.052DOI Listing
March 2009

Source apportionment of human personal exposure to volatile organic compounds in homes, offices and outdoors by chemical mass balance and genetic algorithm receptor models.

Sci Total Environ 2008 Dec 25;407(1):122-38. Epub 2008 Sep 25.

Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India.

A number of past studies have shown the prevalence of a considerable amount of volatile organic compounds (VOCs) in workplace, home and outdoor microenvironments. The quantification of an individual's personal exposure to VOCs in each of these microenvironments is an essential task to recognize the health risks. In this paper, such a study of source apportionment of the human exposure to VOCs in homes, offices, and outdoors has been presented. Air samples, analysed for 25 organic compounds and sampled during one week in homes, offices, outdoors and close to persons, at seven locations in the city of Leipzig, have been utilized to recognize the concentration pattern of VOCs using the chemical mass balance (CMB) receptor model. In result, the largest contribution of VOCs to the personal exposure is from homes in the range of 42 to 73%, followed by outdoors, 18 to 34%, and the offices, 2 to 38% with the corresponding concentration ranges of 35 to 80 microg m(- 3), 10 to 45 microg m(- 3) and 1 to 30 microg m(- 3) respectively. The species such as benzene, dodecane, decane, methyl-cyclopentane, triethyltoluene and trichloroethylene dominate outdoors; methyl-cyclohexane, triethyltoluene, nonane, octane, tetraethyltoluene, undecane are highest in the offices; while, from the terpenoid group like 3-carane, limonene, a-pinene, b-pinene and the aromatics toluene and styrene most influence the homes. A genetic algorithm (GA) model has also been applied to carry out the source apportionment. Its results are comparable with that of CMB.
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http://dx.doi.org/10.1016/j.scitotenv.2008.08.025DOI Listing
December 2008

Association between indoor renovation activities and eczema in early childhood.

Int J Hyg Environ Health 2006 May 21;209(3):241-7. Epub 2006 Feb 21.

Department of Human Exposure Research and Epidemiology, UFZ Leipzig-Halle, Permoserstrasse 15, 04318 Leipzig, Germany.

Background: Other factors besides a genetic disposition seem to play a role in the development of allergic disorders. Exposure to risk factors such as indoor air pollution is becoming increasingly interesting, especially during early childhood.

Methods: Within an epidemiological study (LISS: Leipzig infection, allergy and airway diseases study among school starters, involving 2536 children, birth cohort 1991/92, carried out in 1997/98) the effect of indoor exposure on physician-confirmed eczema and allergic symptoms has been investigated. The exposure situation has been characterized on hand of the redecoration activities (painting, floor covering and new furniture) before birth and in the first years of life.

Results: Highly exposed children showed a significant effect on allergic disorders. The lifetime prevalences without any vs. all three redecoration activities were for allergic symptoms 9.3% vs. 17.2% and for eczema 11.5% vs. 20.4%. Adjusted for confounders, the redecoration associated burden led to odds ratios of 1.8 (95% CI: 1.3-2.6) for allergic symptoms and 1.9 (95% CI: 1.4-2.7) for eczema.

Conclusion: Exposure emissions due to redecoration activities seem to be associated with the risk of eczema and allergic symptoms. Thus, prevention of allergic disorders should include the avoidance of such activities around birth and in the first year of life.
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http://dx.doi.org/10.1016/j.ijheh.2006.01.003DOI Listing
May 2006

Spatiotemporal distribution of airborne mould spores in apartments.

Mycol Res 2003 Nov;107(Pt 11):1361-71

Department of Human Exposure Research and Epidemiology, TUFZ Centre for Environmental Research Leipzig-Halle, Leipzig, Germany.

Indoor air contamination with mould spores currently experiences an increasing interest with respect to their relevance to health. To assess adverse health effects, epidemiological studies combine the health outcome of individuals with their concomitant exposure to airborne spores, which is observed, for example, during the current month. While the latter is representative for the studied period, health effects might also be the result of long term-exposure or emerge in consequence of a peak of pollution throughout the year. To consider such questions, additional information about the spatiotemporal distribution of airborne spores is necessary. This paper aims at elucidating the spatial and temporal variation of spore concentrations in Leipzig, Germany. The analysis is based on 1165 matched pairs of indoor and outdoor measurements taken in the period 1998-2002. All data were collected in the frame of previous epidemiological studies and refer to apartments. The analysis comprised spore concentrations (as CFU m(-3) in air) of the most important genera, such as Penicillium, Aspergillus, Alternaria, Mucorales, Cladosporium, and also for yeasts. We found two groups of fungi differing in their spatiotemporal distribution. As this behaviour can be explained by the predominant origin and growing conditions, we call them indoor-relevant and outdoor-relevant genera. Penicillium species are a representative of the former group, while the latter is well represented by Cladosporium. In the studied period we did not observe a clear trend in the spore concentration. Outdoors there is a year-to-year variation of Cladosporium spore concentrations, which follow the prevalent climatic conditions. For the spore concentration of the outdoor-relevant group a significant annual cycle was observed. Highest concentrations occurred during the summer months and were about 100 x the winter burden. That means, for a direct comparison of measurements of spore concentrations taken during different months the season has to be considered. We summarise the findings in a seasonal model, which is fitted to our measurements. Based on the model we developed a procedure for seasonal adjustment, which enabled us to estimate the annual peak spore concentration utilising one monthly observation.
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http://dx.doi.org/10.1017/s0953756203008566DOI Listing
November 2003

Longitudinal modelling of respiratory symptoms in children.

Int J Biometeorol 2002 Dec 21;47(1):35-48. Epub 2002 Aug 21.

Department of Human Exposure Research and Epidemiology, UFZ-Centre for Environmental Research Leipzig-Halle, PO Box 500135, 04301 Leipzig, Germany.

A panel of 277 children, aged 3-7 years, was used to study the association between air pollution (O(3), SO(2), NO(2), and total suspended particles), meteorological factors (global radiation, maximum daytime temperature, daily averages of vapour pressure and air humidity) and respiratory symptoms. For 759 days the symptoms were recorded in a diary and modelling was based on a modification of the method proposed by Korn and Whittemore (Biometrics 35: 795-798, 1979). This approach (1) comprises an extension using environmental parameters at different time scales, (2) addresses the suitability of using the daily fraction of symptomatic individuals to account for inter-individual interactions and (3) enables the most significant weather effects to be identified. The resulting model consisted of (1) an individual specific intercept that takes account of the population's heterogeneity, (2) the individual's health status the day before, (3) a long-term meteorological effect, which may be either the squared temperature or global radiation in interaction with temperature, (4) the short-term effect of sulfur dioxide, and (5) the short-term effect of an 8-h ozone concentration above 60 microg/m(3). Using the estimated parameters as input to a simulation study, we checked the quality of the model and demonstrate that the annual cycle of the prevalence of respiratory symptoms is associated to atmospheric covariates. Individuals suffering from allergy have been identified as a group of a particular susceptibility to ozone. The duration of respiratory symptoms appears to be free of scale and follows an exponential distribution function, which confirms that the symptom record of each individual follows a Poisson point-process. This supports the assumption that not only respiratory diseases, but also respiratory symptoms can be considered an independent measure for the health status of a population sample. Since a point process is described by only one parameter (namely the intensity of the point process), it is appropriate for records of respiratory symptoms to identify only one model which covers both the occurrence and duration of symptoms.
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http://dx.doi.org/10.1007/s00484-002-0142-2DOI Listing
December 2002

On the probability model for asthma attacks.

Authors:
Uwe Schlink

J Theor Biol 2002 Apr;215(4):405-14

Department of Human Exposure Research and Epidemiology, 04301 Leipzig, Germany.

In environmental epidemiology, the impact of environmental agents on symptoms or health status is of interest. This influence is described quantitatively in the theory of Whittemore & Keller (1979). They formulated a logistic model for individuals that is useful in evaluation of panel studies in which each participant protocols whether he does or does not have a certain symptom each day. In the present paper an equation for the prevalence of symptoms in the study population that is defined as the fraction of symptomatic subjects is deduced from the model for individuals. The model for the aggregated quantity depends on the individuals' parameters in a nonlinear manner. The relationship between the individual-based model and the corresponding population-based model is illustrated by means of a simulated panel. Bayesian estimates of the parameters are calculated and compared for both approaches. Bayesian inference enables to apply the prevalence model to a population of non-identical individuals. For such a heterogeneous population, we observe an attenuation of environmental effects on the aggregated symptom prevalence in comparison to the individual-based approach. The presented theory is applicable not only to panel studies but also in time-series analysis of prevalences and incidences.
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http://dx.doi.org/10.1006/jtbi.2002.2526DOI Listing
April 2002