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Acute effects of summer air pollution on respiratory function in primary school children in southern England.

BACKGROUND: There is growing concern about health effects of air pollution in the UK. Studies in the USA have reported adverse effects on lung function among children but no comparable studies have been published in the UK. This study investigates the relationship between daily changes in ambient air pollution and short term variations in lung function in a panel of school children. METHODS: One hundred and fifty four children aged 7-11 attending a primary school adjacent to a major motorway in Surrey, south-east England, were studied. Bellows spirometry was performed daily on 31 schooldays between 6 June and 21 July 1994. Levels of ozone, nitrogen dioxide, and particulates of less than 10 microns in diameter (PM10) were measured continuously at the school and the pollen count was measured six miles away. Relationships between daily changes in forced expiratory volume in 0.75 seconds (FEV0.75), forced vital capacity (FVC), the FEV0.75/FVC ratio and pollutants were analysed using separate autoregressive models for each child. A weighted average of the resulting slopes was then calculated. RESULTS: There was a significant inverse relationship between daily mean PM10 levels lagged one day and FVC, with a reduction in lung function of 1% (95% CI 0.3% to 2%) across the whole range of PM10 levels (20-150 micrograms/m3). The effect on FEV0.75 was similar (-0.5%) but was not significant when weighted by 1/SE2 (95% CI -1.2% to 0.2%). There was no effect of PM10 levels on the FEV0.75/FVC ratio. No significant association was seen between FEV0.75, FVC, or the FEV0.75/FVC ratio and either ozone or nitrogen dioxide levels. There was no evidence that wheezy children were more affected than healthy children. Pollen levels on the previous day had no effect on lung function and did not change the air pollution results. CONCLUSIONS: There is a very small, but statistically significant, adverse effect of airborne respirable particulate matter, measured as PM10, on lung function in this study group. There is no evidence for an inverse association of lung function with levels of ozone or NO2 measured on the previous day.

Air Pollutants↗

Peak expiratory flow variability, bronchial responsiveness, and susceptibility to ambient air pollution in adults.

Bronchial hyperresponsiveness (BHR) and peak expiratory flow (PEF) variability are associated expressions of airway lability, yet probably reflect different underlying pathophysiologic mechanisms. We investigated whether both measures can be used interchangeably to identify subjects who are susceptible to ambient air pollution. Data on BHR (>= 20% fall in FEV1), PEF variability (ampl%mean PEF > 5% on any day during an 8-d period with low air pollution levels) and diary data on upper and lower respiratory symptoms, cough, and phlegm were collected in 189 subjects (48-73 yr). The acute effects (lag0) of particulate matter with a diameter less than 10 micrometers (PM10), black smoke, SO2 and NO2 on the prevalence of symptoms were estimated with logistic regression. In subjects with airway lability, both when expressed as PEF variability (69%) and BHR (28%), the prevalence of symptoms increased significantly with increasing levels of air pollution, especially in those with the greater PEF variability (n = 55, 29%). We found no such consistent positive associations in adults without airway lability. PEF variability, and to a smaller extent BHR, can be used to identify adults who are susceptible to air pollution. Though odds ratios were rather low (ranging from 1.13 to 1.41), the impact on public health can be substantial because it applies to large populations.

Acute Disease↗

A case-crossover analysis of out-of-hospital coronary deaths and air pollution in Rome, Italy.

RATIONALE: Out-of-hospital coronary heart disease death is a major public health problem, but the association with air pollution is not well understood. OBJECTIVES: We evaluated the association between daily ambient air pollution levels (particle number concentration [PNC]--a proxy for ultrafine particles [diameter < 0.1 microm], mass of particles with diameter less than 10 microm [PM10]; CO, NO2, and O3) and the occurrence of fatal, nonhospitalized coronary events. METHODS: Subjects were 5,144 out-of-hospital fatalities (410-414, International Classification of Diseases-9; 1998-2000) who had been residents of Rome. Hospitalizations during the 3 yr before death were considered to identify comorbidities (e.g., diabetes, hypertension, heart failure, dysrhythmia, chronic obstructive pulmonary disease). Statistical analyses were performed using a case-crossover design. MEASUREMENTS AND MAIN RESULTS: The association with out-of-hospital coronary deaths was statistically significant for PNC, PM10, and CO. Air pollution on the day of death had the strongest effect (e.g., 7.6% increase [95% confidence interval, 2.0-13.6%]) for an interquartile range of PNC, 27,790 particles/cm3. The 65-74- and 75+-yr age groups were at higher risk than the 35-64-yr age group, and there was a suggestion of effect modification for people with hypertension and chronic obstructive pulmonary disease. CONCLUSIONS: Air pollutants originating from combustion processes, including ultrafine particles, are related to fatal, nonhospitalized coronary events. The effect is stronger among people over 65 years of age, but is not limited to a group with a specific comorbidity.

Aged↗

A Fuzzy Markov approach for assessing groundwater pollution potential for landfill siting.

This study presents a Fuzzy Markov groundwater pollution potential assessment approach to facilitate landfill siting analysis. Landfill siting is constrained by various regulations and is complicated by the uncertainty of groundwater related factors. The conventional static rating method cannot properly depict the potential impact of pollution on a groundwater table because the groundwater table level fluctuates. A Markov chain model is a dynamic model that can be viewed as a hybrid of probability and matrix models. The probability matrix of the Markov chain model is determined based on the groundwater table elevation time series. The probability reflects the likelihood of the groundwater table changing between levels. A fuzzy set method is applied to estimate the degree of pollution potential, and a case study demonstrates the applicability of the proposed approach. The short- and long-term pollution potential information provided by the proposed approach is expected to enhance landfill siting decisions.

Forecasting↗

Air pollution and mortality in The Netherlands: are the elderly more at risk?

The association between daily mortality and short-term variations in the ambient levels of ozone (O3), black smoke (BS), sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and particulate matter was studied in The Netherlands. Daily total and cause-specific mortality counts (cardiovascular, chronic obstructive pulmonary disease (COPD) and pneumonia), air quality, temperature, relative humidity and influenza data were obtained from 1986-1994. The relationship between daily mortality and air pollution was modelled using Poisson regression analysis. All pollution mortality associations were adjusted for potential confounding due to long-term trends, seasonal trends, influenza epidemics, ambient temperature, ambient relative humidity, day of the week and holidays, using generalised additive models. Statistically significant associations were mostly found in the elderly, that is the age categories of 65-74 and > or = 75 yrs for the pollutants PM10 (particles with a 50%, cut-off aerodynamic diameter of 10 microm), BS, SO2, NO2 and CO. This may partly be due to a better precision of relative risk (RR) estimates for the larger numbers of deaths in these age groups. Significant associations for those < 65 yrs were found for O3 (total and COPD mortality), PM10 (pneumonia), NO2 (pneumonia) and CO (pneumonia). RR estimates for deaths between 45-65 yrs tended to be smaller than those in > 65 yrs, with the exception of ozone; for cardiovascular mortality the RR for PM10, O3 and CO were similar in these age groups. In conclusion, larger relative risks for air pollution were mostly found in the elderly except for ozone and for death-cause pneumonia which showed larger relative risk in younger age groups.

Aged↗

Genetic aspects of susceptibility to air pollution.

Inter-individual variation in human responses to air pollutants suggests that some subpopulations are at increased risk, and it is increasingly clear that genetic background is an important susceptibility factor. Genetically standardised animal models provide useful investigative tools. Linkage analyses using inbred mice identified chromosomal segments (quantitative trait loci (QTL)), with genes controlling susceptibility to the lung inflammatory (chromosome 17), injury (chromosome 11), and hyperpermeability (chromosome 4) responses to ozone (O3) exposure. An immune dysfunction response induced by exposure to sulphate-associated particles is linked to the identical chromosome 17 and 11 QTLs described for O3 susceptibility, thus similar genetic mechanisms may be controlling pulmonary responses to these pollutants. Candidate genes within the QTLs on chromosomes 4 and 17 include the toll-like receptor 4 and the pro-inflammatory cytokine, tumour necrosis factor-alpha, respectively. Functional analyses strongly support a role for these candidate genes in determining susceptibility to O3 and particulates. Because striking linkage homology exists between the human and mouse genomes, candidate susceptibility genes identified in the mouse are likely to aid research aimed at understanding human genetic factors that contribute to differential susceptibility. To date, no studies have examined the interaction between age and genetic background in the development of air pollution-induced lung disease. However, investigations have suggested an influence of age on genetic susceptibility to lung cancer and other diseases, which indicate that an interaction between age and genetic background may be important in air pollution disease pathogenesis.

Age Factors↗

Indoor air pollution and respiratory health in the elderly.

People spend about > or = 80-90%, of their daily time indoors, elderly people especially at home. Thus, it is important to investigate possible health effects of indoor air pollutants and to consider their contributions to the total human exposure. This report summarises current knowledge on health effects of three common indoor air pollutants, respirable suspended particles, nitrogen dioxide and environmental tobacco smoke, with focus on the adults and the elderly. Preliminary findings on exposure distributions and health effects of these pollutants in older subjects of two panel studies carried out in Italian general populations will also be reported. The two indoor pollution studies were performed in the Po Delta area in North Italy (428 subjects and 140 houses investigated) and in Pisa in Central Italy (761 subjects and 282 houses investigated). Individuals aged > or = 65 yrs spent a significantly larger number of hours at home than the other age groups both in winter and in summer. A trend of higher occurrence of acute respiratory symptoms in the presence of environmental tobacco smoke was shown in comparison to the unexposed elderly both in winter (31 versus 29%) and summer (33 versus 16%). The occurrence of acute respiratory symptoms was consistently higher in relation to the high respirable suspended particles-index exposure compared to low exposure (33 versus 27%, in winter, 27 versus 21% in summer). Both the presence of environmental tobacco smoke at home and exposure to the high respirable suspended particles-index were associated with a decrease in the mean daily peak expiratory flow.

Adult↗

Maternal exposure to low-level air pollution and pregnancy outcomes: a population-based study.

BACKGROUND: Recent reports have shown that air pollution may increase the risk of adverse birth outcomes. We have evaluated the relationship between ambient air pollution and the occurrence of low birth weight and preterm delivery using routinely collected data in Lithuania. METHODS: This epidemiological study comprised all singleton newborns (N = 3,988), born to women in 1998, who resided in the City of Kaunas. Birth data and information on maternal characteristics were obtained from the Lithuanian National Birth Register. To estimate residential exposure levels, we used measurements of ambient nitrogen dioxide (NO2) and formaldehyde, which were collected at 12 monitoring posts. Multivariate logistic regression was used to estimate the effect that each pollutant would have on low birth weight (LBW) and premature birth while controlling for potential confounders. RESULTS: Adjusted odds ratios (OR) for LBW increased with increasing formaldehyde exposure (OR2nd tertile = 1.86, 95% CI 1.10-3.16; OR3rd tertile = 1.84, 95% CI 1.12-3.03). Adjusted ORs of preterm birth for the medium and high NO2 tertile exposures were OR = 1.14 (95% CI 0.77-1.68) and OR = 1.68 (95% CI 1.15-2.46), respectively. The risk of preterm birth increased by 25% (adjusted OR = 1.25, 95% CI 1.07-1.46) per 10 microg/m3 increase in NO2 concentrations. An analysis by trimester showed that pregnancy outcomes were associated with first-trimester exposure to air pollutants. However, there were no significant relationships in other pregnancy periods between preterm birth and exposure to formaldehyde or between LBW and NO2 exposure. CONCLUSION: Our findings suggest that in the City of Kaunas there might be a relationship between maternal exposure to ambient formaldehyde and the risk of LBW, as well as between NO2 exposure and the risk of preterm birth.

Adult↗

Outdoor air pollution, low birth weight, and prematurity.

This study tested the hypothesis, suggested by several recent reports, that air pollution may increase the risk of adverse birth outcomes. This study analyzed all singleton live births registered by the Czech national birth register in 1991 in 67 districts where at least one pollutant was monitored in 1990-1991 (n = 108,173). Maternal exposures to sulfur dioxide (SO(2)), total suspended particles (TSP), and nitrous oxides (NO(x)) in each trimester of pregnancy were estimated as the arithmetic means of all daily measurements taken by all monitors in the district of birth of each infant. Odds ratios of low birth weight (< 2,500 g), prematurity (< 37 weeks of gestation), and intrauterine growth retardation (IUGR; < 10th percentile of birth weight for gestational age and sex) were estimated by robust logistic regression. The median (and 25th and 75th percentile) trimester exposures were 32 (18, 56) microg/m(3) for SO(2); 72 (55, 87) microg/m(3) for TSP; and 38 (23, 59) microg/m(3) for NO(x). Low birth weight (prevalence 5.2%) and prematurity (prevalence 4.8%) were associated with SO(2) and somewhat less strongly with TSP. IUGR was not associated with any pollutant. The effects on low birth weight and prematurity were marginally stronger for exposures in the first trimester, and were not attenuated at all by adjustment for socioeconomic factors or the month of birth. Adjusted odds ratios of low birth weight were 1.20 [95% confidence interval (CI), 1.11-1.30] and 1.15 (CI, 1.07-1.24) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester; adjusted odds ratios of prematurity were 1.27 (CI, 1.16-1.39) and 1.18 (CI, 1.05-1.31) for a 50 microg/m(3) increase in SO(2) and TSP, respectively, in the first trimester. Low gestational age accounted for the association between SO(2) and low birth weight. These findings provide further support for the hypothesis that air pollution can affect the outcome of pregnancy.

Air Pollutants↗

Outdoor air pollution and lung cancer.

In the 1950s evidence of an ongoing epidemic of lung cancer in the United States and Western Europe led researchers to examine the role of outdoor air pollution, which was considered by some to be a likely cause. Although epidemiologic research quickly identified the central role of cigarette smoking in this epidemic, and despite progress in reducing outdoor air pollution in Western industrialized countries, concerns that ambient air pollution is causing lung cancer have persisted to the present day. This concern is based on the fact that known carcinogens continue to be released into outdoor air from industrial sources, power plants, and motor vehicles, and on a body of epidemiologic research that provides some evidence for an association between outdoor air pollution and lung cancer. This article reviews the epidemiologic evidence for this association and discusses the limitations of current studies for estimating the lung cancer risk in the general population. It also identifies research needs and suggests possible approaches to addressing outstanding questions.

Air Pollutants↗

Air pollution-associated changes in lung function among asthmatic children in Detroit.

In a longitudinal cohort study of primary-school-age children with asthma in Detroit, Michigan, we examined relationships between lung function and ambient levels of particulate matter < or = 10 microm and < or = 2.5 microm in diameter (PM10 and PM2.5) and ozone at varying lag intervals using generalized estimating equations. Models considered effect modification by maintenance corticosteroid (CS) use and by the presence of an upper respiratory infection (URI) as recorded in a daily diary among 86 children who participated in six 2-week seasonal assessments from winter 2001 through spring 2002. Participants were predominantly African American from families with low income, and > 75% were categorized as having persistent asthma. In both single-pollutant and two-pollutant models, many regressions demonstrated associations between higher exposure to ambient pollutants and poorer lung function (increased diurnal variability and decreased lowest daily values for forced expiratory volume in 1 sec) among children using CSs but not among those not using CSs, and among children reporting URI symptoms but not among those who did not report URIs. Our findings suggest that levels of air pollutants in Detroit, which are above the current National Ambient Air Quality Standards, adversely affect lung function of susceptible asthmatic children.

Adrenal Cortex Hormones↗

Repolarization changes induced by air pollution in ischemic heart disease patients.

Epidemiologic studies report associations between particulate air pollution and cardiovascular morbidity and mortality, but the underlying pathophysiologic mechanisms are still unclear. We tested the hypothesis that patients with preexisting coronary heart disease experience changes in the repolarization parameters in association with rising concentrations of air pollution. A prospective panel study was conducted in Erfurt, East Germany, with 12 repeated electrocardiogram (ECG) recordings in 56 males with ischemic heart disease. Hourly particulate and gaseous air pollution and meteorologic data were acquired. The following ECG parameters reflecting myocardial substrate and vulnerability were measured: QT duration, T-wave amplitude, T-wave complexity, and variability of T-wave complexity. Fixed effect regression analysis was used adjusting for subject, trend, weekday, and meteorology. The analysis showed a significant increase in QT duration in response to exposure to organic carbon; a significant decrease in T-wave amplitude with exposure to ultrafine, accumulation mode, and PM2.5 particles (particles < 2.5 microm in aerodynamic diameter); and a corresponding significant increase of T-wave complexity in association with PM2.5 particles for the 24 hr before ECG recordings. Variability of T-wave complexity showed a significant increase with organic and elemental carbon in the same time interval. This study provides evidence suggesting an immediate effect of air pollution on repolarization duration, morphology, and variability representing myocardial substrate and vulnerability, key factors in the mechanisms of cardiac death.

Aged↗

Personal and ambient air pollution is associated with increased exhaled nitric oxide in children with asthma.

BACKGROUND: Research has shown associations between pediatric asthma outcomes and airborne particulate matter (PM). The importance of particle components remains to be determined. METHODS: We followed a panel of 45 schoolchildren with persistent asthma living in Southern California. Subjects were monitored over 10 days with offline fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation. Personal active sampler exposures included continuous particulate matter < 2.5 microm in aerodynamic diameter (PM2.5), 24-hr PM2.5 elemental and organic carbon (EC, OC), and 24-hr nitrogen dioxide. Ambient exposures included PM2.5, PM2.5 EC and OC, and NO2. Data were analyzed with mixed models controlling for personal temperature, humidity and 10-day period. RESULTS: The strongest positive associations were between FeNO and 2-day average pollutant concentrations. Per interquartile range pollutant increase, these were: for 24 microg/m3 personal PM2.5, 1.1 ppb FeNO [95% confidence interval (CI), 0.1-1.9]; for 0.6 microg/m3 personal EC, 0.7 ppb FeNO (95% CI, 0.3-1.1); for 17 ppb personal NO2, 1.6 ppb FeNO (95% CI, 0.4-2.8). Larger associations were found for ambient EC and smaller associations for ambient NO2. Ambient PM2.5 and personal and ambient OC were significant only in subjects taking inhaled corticosteroids (ICS) alone. Subjects taking both ICS and antileukotrienes showed no significant associations. Distributed lag models showed personal PM2.5 in the preceding 5 hr was associated with FeNO. In two-pollutant models, the most robust associations were for personal and ambient EC and NO2, and for personal but not ambient PM2.5. CONCLUSION: PM associations with airway inflammation in asthmatics may be missed using ambient particle mass, which may not sufficiently represent causal pollutant components from fossil fuel combustion.

Adolescent↗

Adverse effect of air pollution on respiratory health of primary school children in Taiwan.

This study is a part of the Study On Air Pollution and Health In Taiwan (SOAP&HIT), an ongoing research project involving cooperation of several universities in Taiwan. In this study, the objective was to evaluate the effects of ambient air pollution on respiratory symptoms and diseases of school children, in addition to considering indoor air pollution. Six communities were selected: one community located in a rural area (Taihsi), two in urban areas (Keelung and Sanchung), and the other three in petrochemical industrial areas (Toufen, Jenwu, and Linyuan). We sampled 5,072 primary school students in six communities from the main study population of SOAP&HIT. Respiratory health was assessed by evaluation of the children's respiratory symptoms and diseases using a parent-completed questionnaire. Data were analyzed using logistic regression analysis to compute odds ratios of adverse effect. The school children in the urban communities had significantly more respiratory symptoms (day or night cough, chronic cough, shortness of breath, and nasal symptoms) and diseases (sinusitis, wheezing or asthma, allergic rhinitis, and bronchitis) when compared with those living in the rural community. However, only nasal symptoms of children living in the petrochemical communities were more prevalent than in those living in the rural community. Although the association with ambient air pollution is suggestive, the cross-sectional study cannot confirm a causal relationship; thus further studies are needed.

Air Pollution↗

Air pollution and daily mortality in Seoul and Ulsan, Korea.

The relationship between air pollution and daily mortality for the period 1991-1995 was examined in two Korean cities, Seoul and Ulsan. The observed concentrations of sulfur dioxide (SO2; mean = 28.7 ppb), ozone (O3; mean = 29.2 ppb), and total suspended particulates (TSP; mean = 82.3 microg/m3) during the study period were at levels below Korea's current ambient air quality standards. Daily death counts were regressed separately in the two cities, using Poisson regression on SO2, O3, and/or TSP controlling for variability in the weather and seasons. When considered singly in Poisson regression models controlling for seasonal variations and weather conditions, the nonaccidental mortality associated with a 50-ppb increment in a 3-day moving average of SO2 concentrations, including the concurrent day and the preceding 2 days, was 1.078 [95% confidence interval (CI), 1.057-1.099] for Seoul and 1.051 (CI, 0.991-1.115) for Ulsan. The rate ratio was 1.051 (CI, 1.031-1.072) in Seoul and 0.999 (CI, 0. 961-1.039) in Ulsan per 100 microg/m3 for TSP, and 1.015 (CI, 1. 005-1.025) in Seoul and 1.020 (0.889-1.170) in Ulsan per 50 ppb for 1-hr maximum O3. When TSP was considered simultaneously with other pollutants, the TSP association was no longer significant. We observed independent pollution effects on daily mortality even after using various approaches to control for either weather or seasonal variables in the regression model. This study demonstrated increased mortality associated with air pollution at both SO2 and O3 levels below the current World Health Organization recommendations.

Air Pollutants↗

Respiratory changes due to long-term exposure to urban levels of air pollution: a histopathologic study in humans.

STUDY OBJECTIVES: To evaluate the potential associations between long-term exposure to air pollution and histopathologic evidence of damage to the lungs in humans. DESIGN: Lung tissue samples were collected during necropsies of individuals who died due to violent causes, selected on the basis of their exposure background. PATIENTS: The exposed group was composed of individuals who lived in Guarulhos, an area with high mean levels of inhalable particles. The control group was composed of individuals who lived in two cities with economies based on agricultural activities: Ribeirão Preto and Ourinhos. INTERVENTIONS: Information about cigarette smoking and occupational exposure was obtained from family members. MEASUREMENTS AND RESULTS: Morphometric evaluation of the main bronchus was conducted to determine the volume ratio of submucosal glands. Histopathologic alterations of the bronchioli were evaluated by scoring the presence of inflammatory reaction, wall thickening, and secretory hyperplasia. The number of spots of carbon deposition was counted along the regions of lymphatic drainage (visceral pleura and axial connective tissue around bronchi and blood vessels). Statistical analysis was done by means of regression models controlled for age, smoking, and occupational exposure. Lungs collected from the high pollution area presented evidence of more histopathologic damage in comparison to those from the clean environments. These effects were observed even after controlling for individual differences in age, sex, and cigarette smoking levels. CONCLUSIONS: These results suggest that long-term exposure to air pollution may contribute to the pathogenesis of airway disease, and that urban levels of air pollution have adverse effects on the respiratory tract.

Adult↗

Excretion levels of urinary calcium and phosphorus among the inhabitants of Cd-polluted Kakehashi River basin of Japan.

Bone damage caused by exposure to cadmium (Cd) is often seen in Cd-polluted areas, and increased excretion of calcium (Ca) in urine is thought to be an important factor affecting bone damage. In order to clarify the significance of urinary Ca excretion in bone damage, we investigated the urinary excretion levels of Ca and phosphorus (P) of inhabitants of a Cd-polluted area and compared them to those of nonexposed subjects, and explored the possible association between urinary Ca or P and beta2-microglobulin (beta2-MG). The target subjects were 3164 inhabitants of the Cd-polluted Kakehashi River basin. Ca and Ca/P measurements were significantly higher in the Cd-polluted area than in the controls. In multiple-regression analysis, where either Ca or P was used as the criterion variable, and age, Cd, and beta2-MG were used as explanatory variables, there were positive associations between Ca and Cd and beta2-MG in both sexes. Therefore, the increased excretion level of Ca was the result of renal dysfunction. Bone damage is not thought to be caused by increased excretion of Ca alone because urinary excretion levels of Ca do not differ greatly between people with and without bone damage.

Adult↗

Environmental pollution in central and eastern European countries: a basis for cancer epidemiology.

The main objective of this paper is to discuss the environmental issues in the countries of central and eastern Europe (CCEE) and to show their significance for cancer epidemiology. Of known cancer risk factors that may be related to environmental exposure in the CCEE, tobacco smoking is probably the most important. The worsening trends in cancer mortality noted in middle-aged men in the CCEE can be attributed to smoking. Other lifestyle factors that interact with environmental hazards include high alcohol consumption and unhealthy nutrition. Among other factors, the most common environmental exposure in the CCEE that has potential adverse effects on health in terms of cancer incidence is related to high levels of ambient and indoor pollutants exceeding the air quality guidelines of the World Health Organization. Millions of people, usually in urban areas, are estimated to be exposed to such levels of pollution. Outdoor air pollution is a substantial environmental problem in many areas of the CCEE, where heavy industries are concentrated without adequate technology for emission control. Chemically contaminated drinking water provides a major route of exposure for many potential environmental health hazards. The pollution of water resources, including groundwaters, by industrial and agricultural wastes is a widespread problem in both the CCEE and the former USSR. An estimated 13% of treatment plants in the Russian Federation lack the necessary equipment to treat drinking water, particularly for disinfection, to meet the required standards. Many countries in the region have problems in rural areas, where the networks are small or consumers depend on private wells, and treatment of drinking water is either poor or nonexistent. Consequently, because the standards are difficult to meet, drinking-water accumulates high levels of arsenic and nitrates. The main concern is nitrate, arsenic, fluoride, and pesticides. In countries like Bulgaria, Hungary, Romania, and Slovakia, locations are known where nitrate concentration in drinking water are high enough to cause methemoglobinemia. Lack of appropriate data hamper valid estimates of the extent of unhealthy working conditions or of poor housing conditions. Unsafe industrial installations are potential environmental health hazards, the possible scale of which is difficult to estimate reasonably.

Adolescent↗