Estimating the effect of air pollution from a coal-fired power station on the development of children's pulmonary function

Using geographical information systems (GIS) tools, the present study analyzed the association between children's lung function development and their long-term exposure to air pollution. The study covered the cohort of 1492 schoolchildren living in the vicinity of a major coal-fired power station in the Hadera sub-district of Israel. In 1996 and 1999, the children underwent subsequent pulmonary function tests (PFT) (forced vital capacity (FVC) and forced expiratory volume during the first second (FEV(1))), and the children's parents completed a detailed questionnaire on their health status and household characteristics. A negative association was found between changes in the results of PFT and the estimated individual levels of air pollution. A sensitivity test revealed a FEV(1) decline from -4.3% for the average pollution level to -10.2% for the high air pollution level. The results of a sensitivity test for FVC were found to be similar. Association with the reported health status was found to be insignificant. As we conclude, air pollution from a coal-fired power station, although not exceeding local pollution standards, had a negative effect on children's lung function development. As argued, previous studies carried out in the region failed to show the above association because they were based on zone approaches that assign average concentration levels of air pollutants to all individuals in each zone, leading to a misclassification bias of individual exposure.     

Individual exposure estimates may be erroneous when spatiotemporal variability of air pollution and human mobility are ignored

This study aims to empirically demonstrate the necessity to consider both the spatiotemporal variability of air pollution and individual daily movement patterns in exposure and health risk assessment. It compares four different types of exposure estimates generated by using (1) individual movement data and hourly air pollution concentrations; (2) individual movement data and daily average air pollution data; (3) residential location and hourly pollution levels; and (4) residential location and daily average pollution data. These four estimates are significantly different, which supports the argument that ignoring the spatiotemporal variability of environmental risk factors and human mobility may lead to misleading results in exposure assessment. Additionally, three-dimensional (3D) geovisualization presented in the paper shows how person-specific space-time context is generated by the interactions between air pollution and an individual, and how the different individualized contexts place individuals at different levels of health risk.     

Children's exposure assessment: a review of factors influencing Children's exposure, and the data available to characterize and assess that exposure

We review the factors influencing children's exposure to environmental contaminants and the data available to characterize and assess that exposure. Children's activity pattern data requirements are demonstrated in the context of the algorithms used to estimate exposure by inhalation, dermal contact, and ingestion. Currently, data on children's exposures and activities are insufficient to adequately assess multimedia exposures to environmental contaminants. As a result, regulators use a series of default assumptions and exposure factors when conducting exposure assessments. Data to reduce uncertainty in the assumptions and exposure estimates are needed to ensure chemicals are regulated appropriately to protect children's health. To improve the database, advancement in the following general areas of research is required: identification of appropriate age/developmental benchmarks for categorizing children in exposure assessment; development and improvement of methods for monitoring children's exposures and activities; collection of activity pattern data for children (especially young children) required to assess exposure by all routes; collection of data on concentrations of environmental contaminants, biomarkers, and transfer coefficients that can be used as inputs to aggregate exposure models.     

Indoor and outdoor air pollution: tobacco smoke, moulds and diseases in infants and children

Although outdoor air pollution first brought the issue of air pollution health effects to public attention, it is now indoor air pollution that likely has the greatest impact on children's health. The World Health Organization estimates that the global burden of disease from indoor air pollution is far greater than the burden from outdoor air pollution. This review focuses on two indoor pollutants, one that has been well studied, and another that deserves additional study. There is very strong evidence about the harmful effects of tobacco. Policy to decrease children's tobacco exposure and use should be implemented without delay. The emerging findings linking household inhalation of mould spores and infant pulmonary hemorrhage merit follow-up in other countries, because they may provide clues to some deaths from the sudden infant death syndrome.     

Comparison of spatial interpolation methods for the estimation of air quality data

We recognized that many health outcomes are associated with air pollution, but in this project launched by the US EPA, the intent was to assess the role of exposure to ambient air pollutants as risk factors only for respiratory effects in children. The NHANES-III database is a valuable resource for assessing children's respiratory health and certain risk factors, but lacks monitoring data to estimate subjects' exposures to ambient air pollutants. Since the 1970s, EPA has regularly monitored levels of several ambient air pollutants across the country and these data may be used to estimate NHANES subject's exposure to ambient air pollutants. The first stage of the project eventually evolved into assessing different estimation methods before adopting the estimates to evaluate respiratory health. Specifically, this paper describes an effort using EPA's AIRS monitoring data to estimate ozone and PM10 levels at census block groups. We limited those block groups to counties visited by NHANES-III to make the project more manageable and apply four different interpolation methods to the monitoring data to derive air concentration levels. Then we examine method-specific differences in concentration levels and determine conditions under which different methods produce significantly different concentration values. We find that different interpolation methods do not produce dramatically different estimations in most parts of the US where monitor density was relatively low. However, in areas where monitor density was relatively high (i.e., California), we find substantial differences in exposure estimates across the interpolation methods. Our results offer some insights into terms of using the EPA monitoring data for the chosen spatial interpolation methods.     

Air pollution around schools is linked to poorer student health and academic performance

Exposing children to environmental pollutants during important times of physiological development can lead to long-lasting health problems, dysfunction, and disease. The location of children's schools can increase their exposure. We examined the extent of air pollution from industrial sources around public schools in Michigan to find out whether air pollution jeopardizes children's health and academic success. We found that schools located in areas with the highest air pollution levels had the lowest attendance rates-a potential indicator of poor health-and the highest proportions of students who failed to meet state educational testing standards. Michigan and many other states currently do not require officials considering a site for a new school to analyze its environmental quality. Our results show that such requirements are needed. For schools already in existence, we recommend that their environmental quality should be investigated and improved if necessary.     

Traffic-related outdoor air pollution and respiratory symptoms in children: the impact of adjustment for exposure measurement error

BACKGROUND: Outdoor concentrations of soot and nitrogen dioxide (NO2) outside of schools have been associated with children's respiratory and eye symptoms. We assessed how adjustments for measurement error affect these associations. METHODS: Concentrations of air pollutants outside children's schools were validated by personal measurements of exposure to traffic-related air pollution. We estimated prevalence ratios of 4 health outcomes (current wheeze, conjunctivitis, phlegm, and elevated total serum immunoglobulin E) using school outdoor measurements, and then adjusted for measurement error using the personal exposure data and applying a regression calibration method. The analysis adjusting for measurement error was carried out using a main study/external validation design. RESULTS: Adjusting for measurement error produced effect estimates related to soot and NO2 that were 2 to 3 times higher than in the original study. The adjusted prevalence ratio for current phlegm was 5.3 (95% confidence interval = 1.2-23) for a 9.3 microg/m3 increase in soot, and 3.8 (1.0-14), for a 17.6 microg/m3 increase in NO2, compared with the original results of 2.2 (1.3-3.9) and 1.8 (1.1-2.8), respectively. Corrections were of similar magnitude for the prevalence of current wheeze, current conjunctivitis, and total elevated total immunoglobulin E. CONCLUSIONS: The estimated effects of outdoor air pollution on respiratory and other health effects in children may be substantially attenuated when based on exposure measurements outside schools instead of personal exposure.     

Short term effect of urban air pollution on respiratory insufficiency due to chronic obstructive pulmonary disease. Synthesis of studies published from 1962 to January 2000

This review presents a synthesis of studies published from 1962 to 2000 on the relations between air pollution and chronic obstructive pulmonary disease (COPD): 12 ecological epidemiological studies, 6 epidemiological panel studies, and 11 controlled human exposure trials. The controlled trials, ecological time-based epidemiological studies and panels are examined successively followed by a discussion of their methodology and results. The controlled trials either do no highlight effects or show effects having no clinical significance since variations are similar to physiological variability. For epidemiological studies reporting individual data, the results point to a particle effect (two studies). This effect of particles is found in ecological studies which also describe an impact of ozone, sometimes of sulfur dioxide and less often of nitrogen dioxide. In conclusion, patients suffering from COPD are generally regarded as a group sensitive to air pollution, as suggested by the results of numerous ecological epidemiological studies. Rare individual studies provide a few arguments supporting this assumption.     

Children at risk: measuring racial/ethnic disparities in potential exposure to air pollution at school and home

STUDY OBJECTIVE: This paper addresses the environmental justice implications of children's health by exploring racial/ethnic disparities in potential exposure to air pollution, based on both school and home locations of children and three different types of pollution sources, in Orange County, Florida, USA. METHODS: Using geocoded school and residence locations of 151 709 children enrolled in the public school system, distribution functions of proximity to the nearest source are generated for each type of air pollution source in order to compare the exposure potential of white, Hispanic, and black children. Discrete buffer distances are utilised to provide quantitative comparisons for statistical testing. MAIN RESULTS: At any given distance from each type of pollution source, the cumulative proportion of Hispanic or black children significantly exceeds the corresponding proportion of white children, for both school and home locations. Regardless of race, however, a larger proportion of children are potentially exposed to air pollution at home than at school. CONCLUSIONS: This study addresses the growing need to consider both daytime and nighttime activity patterns in the assessment of children's exposure to environmental hazards and related health risks. The results indicate a consistent pattern of racial inequity in the spatial distribution of all types of air pollution sources examined, with black children facing the highest relative levels of potential exposure at both school and home locations.     

鞍山市大气污染对儿童呼吸系统健康的影响

目的探讨空气污染对儿童呼吸系统健康的危害.方法于2002年4月,在鞍山市轻、中、重污染区随机抽取小学和幼儿园各1所,学校内的所有学生作为调查对象(共1951人),调查不同污染区的儿童健康状况及室内外环境.结果鞍山市儿童持续咳嗽、持续咯痰、哮喘、哮喘现患、喘鸣及喘鸣样症状的发生率分别为9.48%,4.82%,1.33%,0.92%,6.30%,4.97%.幼儿哮喘、哮喘现患,喘鸣、喘鸣样症状发生率均高于学龄儿童;性别间差异无统计学意义.重污染区儿童持续咳嗽和持续咯痰的发生率高于轻污染区儿童的发生率(P＜0.05).随着住房与交通干线距离的接近,儿童呼吸系统疾病的发生率也呈增高趋势.易感因素与室外空气污染的联合作用较强,呼吸系统各种疾病的发生率均以受大气污染影响的易感儿童为高,无大气污染影响的非易感儿童发生率为低.结论室外空气污染是儿童呼吸系统健康的影响因素.     

Assessing the health impacts of air pollution: a re-analysis of the Hamilton children's cohort data using a spatial analytic approach

The objective of this paper was to reassess children's exposure to air pollution as well as investigate the importance of other covariates of respiratory health. We re-examined the Hamilton Children's Cohort (HCC) dataset with enhanced spatial analysis methods, refined in the approximately two decades since the original study was undertaken. Children's exposure to air pollution was first re-estimated using kriging and land-use regression. The land-use regression model performed better, compared to kriging, in capturing local variation of air pollution. Multivariate linear and logistic regression analysis was then applied for the study of potential risk factors for respiratory health. Findings agree with the HCC study-results, confirming that children's respiratory health was associated with maternal smoking, hospitalization in infancy and air pollution. However, results from this study reveal a stronger association between children's respiratory health and air pollution. Additionally, this study demonstrated associations with low-income, household crowding and chest illness in siblings.     

Fine particles, a major threat to children

BACKGROUND: There is a growing body of evidence for serious health consequences of exposure to ambient air pollution. The general question of who is susceptible is one of the most important gaps in current knowledge regarding particulate matter (PM)-related health effects. Who is susceptible depends on the specific health endpoint being evaluated and the level and length of exposure. Here, we restrict the review on the impact of fine particle exposure on children's health to the following outcomes: infant death, lung function, respiratory symptoms and reproductive outcomes. METHODS: This is a strategic review of children's susceptibility to ambient fine particles and characteristics of infant and children which underlie their increased susceptibility to PM. RESULTS: Ambient fine PM is associated with intra-uterine growth retardation, infant mortality; it is associated with impaired lung function and increased respiratory symptoms, particularly in asthmatics. Concerning infant mortality, exposure to PM is strongly and consistently associated with postneonatal respiratory mortality and less consistently with sudden infant death syndrome. Although most of the studies reported adverse effects for this health outcome, the evidence is weaker than for infant death. Exposure to fine PM has been associated with impaired lung function and lung function growth. Most of the studies reported increased prevalence of symptom with increased exposure to fine PM. CONCLUSION: Fine PM is a major threat to children, because of their higher exposure to PM compared to adults, the immature state of the lung in childhood and also of the immune function at birth. The first months of life might be a period of particular sensitivity. Although the mechanisms of air pollution effects have not yet been completely understood, pregnant women, infants and children need specific protection against exposure to fine particles.     

Case-crossover analyses of air pollution exposure data: referent selection strategies and their implications for bias

The case-crossover design has been widely used to study the association between short-term air pollution exposure and the risk of an acute adverse health event. The design uses cases only; for each individual case, exposure just before the event is compared with exposure at other control (or "referent") times. Time-invariant confounders are controlled by making within-subject comparisons. Even more important in the air pollution setting is that time-varying confounders can also be controlled by design by matching referents to the index time. The referent selection strategy is important for reasons in addition to control of confounding. The case-crossover design makes the implicit assumption that there is no trend in exposure across the referent times. In addition, the statistical method that is used-conditional logistic regression-is unbiased only with certain referent strategies. We review here the case-crossover literature in the air pollution context, focusing on key issues regarding referent selection. We conclude with a set of recommendations for choosing a referent strategy with air pollution exposure data. Specifically, we advocate the time-stratified approach to referent selection because it ensures unbiased conditional logistic regression estimates, avoids bias resulting from time trend in the exposure series, and can be tailored to match on specific time-varying confounders.     

A measurement-error model for binary and ordinal regression

Exposure assessment poses special problems in air pollution epidemiology. This paper proposes a probit regression model for binary and ordinal outcomes that uses exposure validation information to develop estimates for the coefficient of the true exposure when only the inaccurate 'surrogate' measure of exposure is available for the individuals in the health study. This method is closely related to recently developed measurement-error methods, and is based on the assumption that the outcome and the surrogate exposure are conditionally independent given the true exposure. A test statistic is proposed for checking this conditional independence assumption when more than one surrogate is available, and an interpretation of the coefficient estimate is provided in the event that the assumption is violated. The methods are applied to an example involving nitrogen dioxide exposure and wheeze in children.     

Relative pesticide and exposure route contribution to aggregate and cumulative dose in young farmworker children

The Child-Specific Aggregate Cumulative Human Exposure and Dose (CACHED) framework integrates micro-level activity time series with mechanistic exposure equations, environmental concentration distributions, and physiologically-based pharmacokinetic components to estimate exposure for multiple routes and chemicals. CACHED was utilized to quantify cumulative and aggregate exposure and dose estimates for a population of young farmworker children and to evaluate the model for chlorpyrifos and diazinon. Micro-activities of farmworker children collected concurrently with residential measurements of pesticides were used in the CACHED framework to simulate 115,000 exposure scenarios and quantify cumulative and aggregate exposure and dose estimates. Modeled metabolite urine concentrations were not statistically different than concentrations measured in the urine of children, indicating that CACHED can provide realistic biomarker estimates. Analysis of the relative contribution of exposure route and pesticide indicates that in general, chlorpyrifos non-dietary ingestion exposure accounts for the largest dose, confirming the importance of the micro-activity approach. The risk metrics computed from the 115,000 simulations, indicate that greater than 95% of these scenarios might pose a risk to children's health from aggregate chlorpyrifos exposure. The variability observed in the route and pesticide contributions to urine biomarker levels demonstrate the importance of accounting for aggregate and cumulative exposure in establishing pesticide residue tolerances in food.     

A behavioral intervention to reduce child exposure to indoor air pollution: identifying possible target behaviors.

Indoor air pollution has been causally linked to acute lower respiratory infections in children younger than 5. The aim of this study was to identify target behaviors for a behavioral intervention to reduce child exposure to indoor air pollution by attempting to answer two research questions: Which behaviors are protective of child respiratory health in the study context? and Which behaviors do mothers recommend to reduce their children's exposure to indoor air pollution? Observations and interviews were conducted with 67 mother-child combinations. The authors recommend that four behavioral clusters should be considered for the main intervention. These are to improve stove maintenance practices, to increase the duration that two ventilation sources are opened while a fire is burning, to reduce the time that children spend close to burning fires, and to reduce the duration of solid fuel burning.     

Quantifying children's aggregate (dietary and residential) exposure and dose to permethrin: application and evaluation of EPA's probabilistic SHEDS-Multimedia model

Reliable, evaluated human exposure and dose models are important for understanding the health risks from chemicals. A case study focusing on permethrin was conducted because of this insecticide's widespread use and potential health effects. SHEDS-Multimedia was applied to estimate US population permethrin exposures for 3- to 5-year-old children from residential, dietary, and combined exposure routes, using available dietary consumption data, food residue data, residential concentrations, and exposure factors. Sensitivity and uncertainty analyses were conducted to identify key factors, pathways, and research needs. Model evaluation was conducted using duplicate diet data and biomonitoring data from multiple field studies, and comparison to other models. Key exposure variables were consumption of spinach, lettuce, and cabbage; surface-to-skin transfer efficiency; hand mouthing frequency; fraction of hand mouthed; saliva removal efficiency; fraction of house treated; and usage frequency. For children in households using residential permethrin, the non-dietary exposure route was most important, and when all households were included, dietary exposure dominated. SHEDS-Multimedia model estimates compared well to real-world measurements data; this exposure assessment tool can enhance human health risk assessments and inform children's health research. The case study provides insights into children's aggregate exposures to permethrin and lays the foundation for a future cumulative pyrethroid pesticides risk assessment.     

Does Traffic-related Air Pollution Explain Associations of Aircraft and Road Traffic Noise Exposure on Children's Health and Cognition? A Secondary Analysis of the United Kingdom Sample From the RANCH Project

The authors examined whether air pollution at school (nitrogen dioxide) is associated with poorer child cognition and health and whether adjustment for air pollution explains or moderates previously observed associations between aircraft and road traffic noise at school and children's cognition in the 2001-2003 Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) project. This secondary analysis of a subsample of the United Kingdom RANCH sample examined 719 children who were 9-10 years of age from 22 schools around London's Heathrow airport for whom air pollution data were available. Data were analyzed using multilevel modeling. Air pollution exposure levels at school were moderate, were not associated with a range of cognitive and health outcomes, and did not account for or moderate associations between noise exposure and cognition. Aircraft noise exposure at school was significantly associated with poorer recognition memory and conceptual recall memory after adjustment for nitrogen dioxide levels. Aircraft noise exposure was also associated with poorer reading comprehension and information recall memory after adjustment for nitrogen dioxide levels. Road traffic noise was not associated with cognition or health before or after adjustment for air pollution. Moderate levels of air pollution do not appear to confound associations of noise on cognition and health, but further studies of higher air pollution levels are needed.     

The individualistic fallacy,ecological studies and instrumental variables: a causal interpretation

The validity of ecological studies in epidemiology for inferring causal relationships has been widely challenged as observed associations could be biased by the Ecological Fallacy. We reconsider the important design components of ecological studies, and discuss the conditions that may lead to spurious associations. Ecological associations are useful and valid when the ecological exposures can be interpreted as Instrumental Variables. A suitable example may be a time series analysis of environmental pollution (e.g. particulate matter with an aerodynamic diameter of <10 micrometres; PM₁₀) and health outcomes (e.g. hospital admissions for acute myocardial infarction) as environmental pollution levels are a cause of individual exposure levels and not just an aggregate measurement. Ecological exposures may also be employed in situations (perhaps rare) where individual exposures are known but their associations with health outcomes are confounded by unknown or unquantifiable factors. Ecological associations have a notorious reputation in epidemiology and individualistic associations are considered superior to ecological associations because of the “ecological fallacy”. We have argued that this is incorrect in situations in which ecological or aggregate exposures can serve as an instrumental variable and associations between individual exposure and outcome are likely to be confounded by unmeasured variables.     

Children's health status in relation to the level and nature of anthropogenic pollution

The frequency of health groups 1 and 2 was studied in children living in the areas of the Orenburg Region, by taking into account the level and nature of their anthropogenic pollution. The pollution indicators of environmental objects (ambient air, drinking water, soil) were analyzed. A cross-sectional population-based study was conducted in 7000 children aged 1 month to 18 years, who lived in the urban and rural areas. In the urban areas, health group 1 and 2 children were 2.2- and 1.6-foldfewer than that in the rural ones, respectively. Ambient air pollution was found to have a priority impact on the children's health.