[Breathing: Ambient Air Pollution and Health - Part III]. / Atmen: Luftschadstoffe und Gesundheit ­ Teil III.

The third part of the DGP statement introduces the current body of knowledge on less studied health outcomes associated with exposure to ambient air pollution: the negative impact on metabolism leading to impaired glucose tolerance and diabetes as well as contribution to the development of neurodegenerative disorders and delayed cognitive function in children. Furthermore, prenatal exposure and adverse effects on mother and child are addressed. Finally, the currently discussed biological mechanisms underlying various health effects associated with exposure to air pollution are described.Differing, but often complementary biological mechanisms create the basis for the diverse health outcomes caused by air pollution. Oxidative stress and a subclinical inflammatory response in the lungs and on a systemic level ("low-grade systemic inflammation") are considered to be key mechanisms. They promote secondary alterations in the body, such as vascular or metabolic processes, and may also result in the currently studied epigenetic phenomena or neuroinflammation. In this context, the health significance of soluble particulate matter and the role of ultrafine particles translocated across biological membranes into blood vessel and transported via the circulation to secondary target organs, such as liver, brain or the fetus, are intensively discussed.Diabetes is one of the leading chronic diseases worldwide, with a prevalence of almost 14 % in Germany. Although lifestyle factors are the main causes, current evidence suggests that long-term exposure to air pollution may additionally increase the risk for type 2 diabetes. Supporting evidence for a causal role of air pollution is provided by studies addressing the regulation of the blood glucose levels in metabolically healthy participants, insulin sensitivity, or pregnancy-related diabetes. Experimental studies provide further support for plausible biological mechanisms. However, prospective studies are needed to gain more evidence, taking multiple lifestyle and environmental factors, such as green space and noise, and an improved individual exposure assessment into account.The aging population has an increased risk of neurodegenerative diseases. First studies point towards a contribution of chronic exposure to air pollution, specifically by particulate matter. Several studies report its association with decreased neurocognitive capacity or an increased prevalence of dementia or Alzheimer's disease in adults. However, the studies are inhomogeneous regarding design, exposure and outcome, leading to inconsistent results. With respect to the influence on neurocognitive development of children, first studies suggest an association between the level of air pollution, e. g. at school, and delayed cognitive development.Even though the evidence for the different biological endpoints during pregnancy is still heterogeneous, the studies generally point towards an adverse impact of air pollution on the maternal and fetal organisms. The strongest evidence exists for low birth weight, with small effect sizes of only some grams, and for a higher incidence of reduced birth weight (< 2500 g). An increased risk for gestational hypertension and preeclampsia underscores the possible impact of exposure to air pollution on the maternal organism. However, the current body of evidence does not yet allow a final conclusion on the influence of intrauterine exposure to air pollution regarding early childhood lung function and development of allergies, particularly in light of the fact that it is hard to distinguish in epidemiological studies between the effects of pre- and postnatal exposure.

[Breathing: Ambient Air Pollution and Health - Part II]. / Atmen: Luftschadstoffe und Gesundheit ­ Teil II.

The second part of the DGP-statement on adverse health effects of ambient air pollution provides an overview of the current ambient air quality in Germany and its development in the past 20 years. Further, effects of air pollution on the cardiovascular system und underlying pathophysiological mechanisms are introduced. Air pollutants form a highly complex and dynamic system of thousands of organic and inorganic components from natural and anthropogenic sources. The pollutants are produced locally or introduced by long-range transport over hundreds of kilometers and are additionally subjected to local meteorological conditions. According to air quality regulations ambient air quality is monitored under uniform standards including immission of particulate matter, up to 2.5 µm (PM2.5) or 10 µm (PM10) in aerodynamic diameter, and of nitrogen dioxide (NO2) or ozone (O3). The clean air measures of recent years led to a continuous decline of air pollution in the past 20 years in Germany. Accordingly, the focus is nowadays directed at population-related health hazards caused by low concentrations of air pollution. Exceeded limits for sulfur dioxide, carbon monoxide, benzene and lead are not detected anymore. Also the number of days with increased ozone concentration declined, although the annual mean concentration is unaltered. Decreasing concentrations of particulate matter and NO2 have been observed, however, about 40 % of the monitoring stations at urban traffic sites still measure values exceeding current limits for NO2. Moreover, the stricter, solely health-based WHO-standards for PM2.5, PM10 and NO2 are still not met so that an optimal protection from air pollution-related health hazards is currently not given for the German population. In recent years, the findings of numerous cross-sectional and longitudinal studies underscored adverse effects of air pollution on the cardiovascular system, especially for particulate matter, although the level of evidence still varies for the different health outcomes. Further, the studies show that cardiovascular health hazards on the population level are of higher relevance than those for the respiratory system. The existing evidence for cardiovascular mortality, hospitalization, ischemic heart diseases, myocardial infarction and stroke can be regarded as strong, while that for heart failure is rather moderate. While the evidence for air pollution-related short-term alteration of the cardiac autonomic balance can be considered as sufficient, long-term effects are still unclear. Likewise, the heterogeneous findings on air pollution-related arrhythmia do currently not allow a distinct conclusion in this regard. A large number of studies support the observation that both, short- and long-term air pollution exposure contribute to increased blood pressure, may impair vascular homeostasis, induce endothelial dysfunction and promote the progression of atherosclerotic lesions. These effects provide reasonable biological explanation for the fatal events associated with exposure to air pollution. Short-term exposure may not pose a significant risk on healthy individuals but may be considered as precursor for fatal events in susceptible populations, while repetitive or long-term exposure may contribute to the development of cardiovascular diseases even in healthy subjects.

Long-term exposure to traffic-related air pollution and insulin resistance in children: results from the GINIplus and LISAplus birth cohorts.

AIMS/HYPOTHESIS: Epidemiological studies that have examined associations between long-term exposure to traffic-related air pollution and type 2 diabetes mellitus in adults are inconsistent, and studies on insulin resistance are scarce. We aimed to assess the association between traffic-related air pollution and insulin resistance in children. METHODS: Fasting blood samples were collected from 397 10-year-old children in two prospective German birth cohort studies. Individual-level exposures to traffic-related air pollutants at the birth address were estimated by land use regression models. The association between air pollution and HOMA of insulin resistance (HOMA-IR) was analysed using a linear model adjusted for several covariates including birthweight, pubertal status and BMI. Models were also further adjusted for second-hand smoke exposure at home. Sensitivity analyses that assessed the impact of relocating, study design and sex were performed. RESULTS: In all crude and adjusted models, levels of insulin resistance were greater in children with higher exposure to air pollution. Insulin resistance increased by 17.0% (95% CI 5.0, 30.3) and 18.7% (95% CI 2.9, 36.9) for every 2SDs increase in ambient NO2 and particulate matter ≤10 µm in diameter, respectively. Proximity to the nearest major road increased insulin resistance by 7.2% (95% CI 0.8, 14.0) per 500 m. CONCLUSIONS/INTERPRETATION: Traffic-related air pollution may increase the risk of insulin resistance. Given the ubiquitous nature of air pollution and the high incidence of insulin resistance in the general population, the associations examined here may have potentially important public health effects despite the small/moderate effect sizes observed.

Respiratory health and individual estimated exposure to traffic-related air pollutants in a cohort of young children.

OBJECTIVES: To estimate long-term exposure to traffic-related air pollutants on an individual basis and to assess adverse health effects using a combination of air pollution measurement data, data from geographical information systems (GIS) and questionnaire data. METHODS: 40 measurement sites in the city of Munich, Germany were selected at which to collect particulate matter with a 50% cut-off aerodynamic diameter of 2.5 microm (PM2.5) and to measure PM2.5 absorbance and nitrogen dioxide (NO2). A pool of GIS variables (information about street length, household and population density and land use) was collected for the Munich metropolitan area and was used in multiple linear regression models to predict traffic-related air pollutants. These models were also applied to the birth addresses of two birth cohorts (German Infant Nutritional Intervention Study (GINI) and Influence of Life-style factors on the development of the Immune System and Allergies in East and West Germany (LISA)) in the Munich metropolitan area. Associations between air pollution concentrations at birth address and 1-year and 2-year incidences of respiratory symptoms were analysed. RESULTS: The following means for the estimated exposures to PM2.5, PM2.5 absorbance and NO2 were obtained: 12.8 microg/m3, 1.7x10(-5) m(-1) and 35.3 mug/m3, respectively. Adjusted odds ratios (ORs) for wheezing, cough without infection, dry cough at night, bronchial asthma, bronchitis and respiratory infections indicated positive associations with traffic-related air pollutants. After controlling for individual confounders, significant associations were found between the pollutant PM2.5 and sneezing, runny/stuffed nose during the first year of life (OR 1.16, 95% confidence interval 1.01 to 1.34) Similar effects were observed for the second year of life. These findings are similar to those from our previous analysis that were restricted to a subcohort in Munich city. The extended study also showed significant effects for sneezing, running/stuffed nose. Additionally, significant associations were found between NO2 and dry cough at night (or bronchitis) during the first year of life. The variable "living close to major roads" (<50 m), which was not analysed for the previous inner city cohort with birth addresses in the city of Munich, turned out to increase the risk of wheezing and asthmatic/spastic/obstructive bronchitis. CONCLUSIONS: Effects on asthma and hay fever are subject to confirmation at older ages, when these outcomes can be more validly assessed.

Evaluation of a sampling strategy for estimation of long-term PM2.5 exposure for epidemiological studies.

As part of the European Community Respiratory Health Survey (ECRHS) PM2.5 (particles collected with an upper 50% cut point of 2.5 microm aerodynamic diameter) was measured using an EPA-WINS (Environmental Protection Agency Well Impactor Ninety-six) sampler. The monitoring schedule was restricted to 7 days per month for one year. Simultaneously, during this one year study period a collocated Harvard Impactor (HI) was run on a daily basis in Erfurt, Germany. Here we validated the reliability of annual, seasonal and monthly means estimated using the ECRHS scheme (measurements taken less than 25% of the whole study period) with the 'true' long-term averages, which were estimated using all available daily means. The daily PM2.5 means, obtained by both instruments operated in parallel, were only slightly different (the mean difference between EPA-WINS and HI was 1.8 microg m(-3) and 2.8 microg m(-3) for the winter means). The values obtained by the two instruments were highly correlated (r = 0.95). In view of that negligible difference, no additional bias was seen with respect to the annual and the winter means estimated by the two different sampling strategies (the difference was 1.7 microg m(-3) and 2.7 microg m(-3), respectively). Monthly means, however, can only be considered to be a crude estimate that may substantially under- or overestimate the true monthly mean value.

Exposure to traffic related air pollutants: self reported traffic intensity versus GIS modelled exposure.

BACKGROUND: In epidemiological studies of the potential health effects of traffic related air pollution, self reported traffic intensity is a commonly used, but rarely validated, exposure variable. METHODS: As part of a study on the impact of Traffic Related Air Pollution on Childhood Asthma (TRAPCA), data from 2633 and 673 infants from the Dutch and the German-Munich cohorts, respectively, were available. Parents subjectively assessed traffic intensity at the home address. Objective exposures were estimated by a combination of spatial air pollution measurements and geographic information system (GIS) based modelling using an identical method for both cohorts. RESULTS: The agreement rates between self reported and GIS modelled exposure--accumulated over the three strata of self assessed traffic intensity--were 55-58% for PM(2.5), filter absorbance (PM(2.5) abs), and nitrogen dioxide in Munich and 39-40% in the Netherlands. Of the self reported low traffic exposed group, 71-73% in Munich and 45-47% in the Netherlands had low modelled exposure to these three air pollutants. Of the self assessed high exposed subgroups in Munich (15% of the total population) and the Netherlands (22% of the total population), only 22-33% and 30-32% respectively had high modelled exposure to the three air pollutants. The subjective assessments tend to overestimate the modelled estimates for PM(2.5) and NO2 in both study areas. When analysis was restricted to the portion of the Dutch cohort living in non-urban areas, the agreement rates were even lower. CONCLUSIONS: Self reported and modelled assessment of exposure to air pollutants are only weakly associated.

Sources and elemental composition of ambient PM(2.5) in three European cities.

Source apportionment of urban fine particle mass (PM(2.5)) was performed from data collected during 1998-1999 in Amsterdam (The Netherlands), Erfurt (Germany) and Helsinki (Finland), using principal component analysis (PCA) and multiple linear regression. Six source categories of PM(2.5) were identified in Amsterdam. They were traffic-related particles (30% of the average PM(2.5)), secondary particles (34%), crustal material (7%), oil combustion (11%), industrial and incineration processes (9%), and sea salt (2%). The unidentified PM(2.5) fraction was 7% on the average. In Erfurt, four source categories were extracted with some difficulties in interpretation of source profiles. They were combustion emissions related to traffic (32%), secondary PM (32%), crustal material (21%) and industrial processes (8%). In Erfurt, 3% of PM(2.5) remained unidentified. Air pollution data and source apportionment results from the two Central European cities were compared to previously published results from Helsinki, where about 80% of average PM(2.5) was attributed to transboundary air pollution and particles from traffic and other regional combustion sources. Our results indicate that secondary particles and local combustion processes (mainly traffic) were the most important source categories in all cities; their impact on the average PM(2.5) was almost equal in Amsterdam and Erfurt whereas, in Helsinki, secondary particles made up for as much as half of the total average PM(2.5).

Elemental composition and sources of fine and ultrafine ambient particles in Erfurt, Germany.

We present the first results of a source apportionment for the urban aerosol in Erfurt, Germany, for the period 1995-1998. The analysis is based on data of particle number concentrations (0.01-2.5 microm; mean 1.8 x 10(4) cm(-3), continuous), the concentration of the ambient gases SO(2), NO, NO(2) and CO (continuous), particle mass less than 2.5 microm (PM(2.5)) and less than 10 microm (PM(10)) (Harvard Impactor sampling, mean PM(2.5) 26.3 micro/m(3), mean PM(10) 38.2 microg/m(3)) and the size fractionated concentrations of 19 elements (impactor sampling 0.05-1.62 microm, PIXE analysis). We determined: (a) the correlations between (i) the 1- and 24-h average concentrations of the gaseous pollutants and the particle number as well as the particle mass concentration and (ii) between the 24-h elemental concentrations; (b) Crustal Enrichment Factors for the PIXE elements using Si as reference element; and (c) the diurnal pattern of the measured pollutants on weekdays and on weekends. The highly correlated PIXE elements Si, Al, Ti and Ca having low enrichment factors were identified as soil elements. The strong correlation of particle number concentrations with NO, which is considered to be typically emitted by traffic, and the striking similarity of their diurnal variation suggest that a sizable fraction of the particle number concentration is associated with emission from vehicles. Besides NO and particle number concentrations other pollutants such as NO(2), CO as well as the elements Zn and Cu were strongly correlated and appear to reflect motor vehicle traffic. Sulfur could be a tracer for coal combustion, however, it was not correlated with any of the quoted elements. Highly correlated elements V and Ni have similar enrichment factors and are considered as tracers for oil combustion.

Traffic-related air pollution and respiratory health during the first 2 yrs of life.

As part of an international collaborative study on the impact of Traffic-Related Air Pollution on Childhood Asthma (TRAPCA), the health effects associated with long-term exposure to particles with a 50% cut-off aerodynamic diameter of 2.5 microm (PM2.5), PM2.5 absorbance, and nitrogen dioxide (NO2) were analysed. The German part of the TRAPCA study used data from subpopulations of two ongoing birth cohort studies (German Infant Nutrition Intervention Programme (GINI) and Influences of Lifestyle Related Factors on the Human Immune System and Development of Allergies in Children (LISA)) based in the city of Munich. Geographic information systems (GIS)-based exposure modelling was used to estimate traffic-related air pollutants at the birth addresses of 1,756 infants. Logistic regression was used to analyse possible health effects and potential confounding factors were adjusted for. The ranges in estimated exposures to PM2.5, PM2.5 absorbance, and NO2 were 11.9-21.9 microg m(-3), 1.38-4.39 x 10(-5) m(-1), and 19.5-66.9 microg x m3, respectively. Significant associations between these pollutants and cough without infection (odds ratio (OR) (95% confidence interval (CI)): 1.34 (1.11-1.61), 1.32 (1.10-1.59), and 1.40 (1.12-1.75), respectively) and dry cough at night (OR (95% CI): 1.31 (1.07-1.60), 1.27 (1.04-1.55), and 1.36 (1.07-1.74), respectively) in the first year of life were found. In the second year of life, these effects were attenuated. There was some indication of an association between traffic-related air pollution and symptoms of cough. Due to the very young age of the infants, it was too early to draw definitive conclusions from this for the development of asthma.

[Environmental surveys in the areas of Bitterfeld, Hettstedt and a comparative area in 1992-2000]. / Umweltmedizinische Untersuchungen im Raum Bitterfeld, im Raum Hettstedt und in einem Vergleichsgebiet 1992-2000.

The aim of the environmental epidemiological study was to determine possible adverse effects on the health of children in the environmentally polluted areas of Bitterfeld and Hettstedt compared to the less polluted area of Zerbst (Eastern Germany). The changes of the health parameters were recorded together with the environmental changes during the time period of 6 years. The study design consisted of three repeated regional cross-sectional studies in 1992/93, 1995/96 and 1998/99. In total, 7,611 questionnaires could be analysed (participation rate: 89%, 75% and 75%). Children living in the most polluted area of Hettstedt had a noticeable higher risk for non-allergic respiratory diseases and symptoms compared to children living in the control area of Zerbst. From 1992 to 1999 a statistically significant decrease in the prevalences of these health outcomes was found. Children without indoor pollutants in their homes had the greatest benefit by the improvement of ambient air quality. The increase in lung function (FVC, FEV1) also underlines the improvement of the respiratory health. Children living in the polluted areas reported allergies more often (physician's diagnosis, allergy specific antibodies). The prevalence of asthma, the bronchial hyperreactivity and atopic eczema was increased within the observational period of 6 years. An increased prevalence was also shown for more severe allergic sensitisation (RAST classes > 17.5 kU/l), while the prevalence of hay fever increased slightly on a non-significant level. The burden with lead and cadmium was higher in children living in polluted areas and decreased during the study period except for 1997 where the lead concentration in blood increased according to the higher lead concentration in settled dust in Hettstedt at that time.

PM25 measurements in ambient aerosol: comparison between Harvard impactor (HI) and the tapered element oscillating microbalance (TEOM) system.

A comparison, based on the regression of 32 daily mean PM25 aerosol loadings determined by a tapered element oscillating microbalance (TEOM) and by a Harvard impactor (HI), is reported for the ambient aerosol of Erfurt (Germany). The PM2.5 concentrations measured by the TEOM were systematically lower then those obtained by the HI. The ratio of the means TEOM/HI was 0.74 and the regression equation is TEOM = 0.69 x HI + 0.071. This result is consistent with reports elsewhere suggesting that semi-volatile aerosol material is lost from the heated sample filter on the TEOM. To verify this assertion, a heating system was developed for the HI which was able to keep the HI sample filter at 50+/-1 degrees C. After the implementation of this heating system, no systematically differences were observed between the TEOM and the heated HI system. The ratio of means was 1.06 and the regression equation TEOM = 1.10 x HI - 0.668. Because the measured levels of ammonium nitrate were very low in Erfurt, we concluded that other compounds like semi-volatile organics were responsible for the loss of particulate material at 50 degrees C.

Air quality in postunification Erfurt, East Germany: associating changes in pollutant concentrations with changes in emissions.

The unification of East and West Germany in 1990 resulted in sharp decreases in emissions of major air pollutants. This change in air quality has provided an opportunity for a natural experiment to evaluate the health impacts of air pollution. We evaluated airborne particle size distribution and gaseous co-pollutant data collected in Erfurt, Germany, throughout the 1990s and assessed the extent to which the observed changes are associated with changes in the two major emission sources: coal burning for power production and residential heating, and motor vehicles. Continuous data for sulfur dioxide, total suspended particulates (TSP), nitric oxide, carbon monoxide, and meteorologic parameters were available for 1990-1999, and size-selective particle number and mass concentration measurements were made during winters of 1991 and 1998. We used hourly profiles of pollutants and linear regression analyses, stratified by year, weekday/weekend, and hour, using NO and SO(2) as markers of traffic- and heating-related combustion sources, respectively, to study the patterns of various particle size fractions. Supplementary data on traffic and heating-related sources were gathered to support hypotheses linking these sources with observed changes in ambient air pollution levels. Substantially decreased (19-91%) concentrations were observed for all pollutants, with the exception of particles in the 0.01-0.03 microm size range (representing the smallest ultrafine particles that were measured). The number concentration for these particles increased by 115% between 1991 and 1998. The ratio of these ultrafine particles to TSP also increased by more than 500%, indicating a dramatic change in the size distribution of airborne particles. Analysis of hourly concentration patterns indicated that in 1991, concentrations of SO(2) and larger particle sizes were related to residential heating with coal. These peaks were no longer evident in 1998 due to decreases in coal consumption and consequent decreased emissions of SO(2) and larger particles. These decreases in coal combustion and the decreased concentrations of SO(2) and particles of larger size classes may have led to decreased particle scavenging and may be partially responsible for the observed increases in ultrafine particles. Traffic-related changes, such as increased numbers of trucks and increased use of diesel vehicles in Erfurt, were also associated with increased number concentrations of ultrafine particles. Morning particle peaks of all sizes were associated with NO and CO (markers for traffic) in both the 1991 and 1998 periods. There were significant differences in the ultrafine particle levels for morning hours between 1991 and 1998, suggesting that traffic was the cause of this increase.

Sources and concentrations of indoor nitrogen dioxide in Hamburg (west Germany) and Erfurt (east Germany).

Here we report indoor and outdoor concentrations of NO2 for Erfurt and Hamburg and assess the contribution of the most important indoor sources (e.g. the presence of gas cooking ranges, smoking) and outdoor sources (traffic exhaust emissions). We examined the relative contribution of the different sources of NO2 to the total indoor NO2 levels in Erfurt and Hamburg. NO2 indoor concentrations in Hamburg were slightly higher than those in Erfurt (i.e. living room: 15 microg m(-3) for Erfurt and 17 microg m(-3) for Hamburg). A linear regression model including the variables, place of residence, season and outdoor NO2 levels, location of the home within the city, housing and occupant characteristics accounted for 38% of the NO2 variance. The most important predictors of indoor NO2 concentrations were gas in cooking followed by other characteristics, such as ventilation or outdoor NO2 level. Residences in which gas was used for cooking, or in which occupants smoked, had substantially higher indoor NO2 concentrations (41 or 18% increase, respectively). An increase in the outdoor NO2 concentration from the 25th to the 75th-percentile (17 microg m(-3)) was associated with a 33% increase in the living room NO2 concentration. Multiple regression analysis for both cities separately illustrated that use of gas for cooking was the major indoor source of NO2. This variable caused a similar increase in the indoor NO2 levels in each city (43% in Erfurt and 47% in Hamburg). However, outdoor sources of NO2 (motor vehicle traffic) contributed more to indoor NO2 levels in Hamburg than in Erfurt.

Respiratory diseases and allergies in two polluted areas in East Germany.

This cross-sectional epidemiological study collected health data for 2,470 school children between 5 and 14 years of age (89% of eligible children) who had lived most of their lives in either one of two counties strongly impacted by industrial pollution (Bitterfeld and Hettstedt) or in a neighboring county without any sources of industrial pollution (Zerbst). The objective of the study was to examine whether regional differences--with respect to the occurrence of childhood respiratory diseases and symptoms or allergies--exist and, if such differences are found, whether they persist when we adjust for the effects of known risk factors such as medical and sociodemographic factors or factors related to the indoor environment. Controlling for medical, sociodemographic, and indoor factors, according to parental reports, children residing in Hettstedt have about a 50% increased lifetime prevalence for physician-diagnosed allergies, eczema, and bronchitis compared to children from Zerbst and about twice the number of respiratory symptoms such as wheeze, shortness of breath, and cough without cold. Sensitization to common aeroallergens according to skin prick tests [odds ratio (OR) = 1.38; 95% confidence interval (CI), 1.02-1.86] and specific IgE levels (OR = 1.75; CI, 1.31-2.33) was more common for children from Hettstedt than children from the nonpolluted county. Bitterfeld children, on the other hand, more often received a diagnosis of asthma and eczema than children residing in Zerbst and also showed slightly increased sensitization rates. In conclusion, industrial pollution related to mining and smelting operations in the county of Hettstedt were associated with a higher lifetime prevalence of respiratory disorders and an increased rate of allergic sensitization in children between the ages of 5 and 14 years. Further studies are needed to determine what role the high dust content of heavy metals plays in Hettstedt.