The burden of heat-related mortality attributable to recent human-induced climate change.

Climate change affects human health; however, there have been no large-scale, systematic efforts to quantify the heat-related human health impacts that have already occurred due to climate change. Here, we use empirical data from 732 locations in 43 countries to estimate the mortality burdens associated with the additional heat exposure that has resulted from recent human-induced warming, during the period 1991-2018. Across all study countries, we find that 37.0% (range 20.5-76.3%) of warm-season heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent. Burdens varied geographically but were of the order of dozens to hundreds of deaths per year in many locations. Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

The joint association of air pollution and noise from road traffic with cardiovascular mortality in a cohort study.

OBJECTIVES: Associations between cardiovascular mortality and air pollution and noise together were investigated. METHODS: Data from the ongoing Netherlands Cohort Study on Diet and Cancer (120,852 subjects; follow-up 1987-1996) were used. Cox proportional hazard analyses were conducted for the association between cardiovascular mortality and exposure to black smoke, traffic intensity on the nearest road and road traffic noise at the home address. RESULTS: The correlations between traffic noise and background black smoke, and traffic intensity on the nearest road were moderate at 0.24 and 0.30, respectively. Traffic intensity was associated with cardiovascular mortality, with highest relative risk (95% confidence interval) for ischaemic heart disease (IHD) mortality being 1.11 (1.03 to 1.20) (increment 10,000 motor vehicles/24 h). Relative risks for black smoke concentrations were elevated for cerebrovascular (1.39 (0.99 to 1.94)) and heart failure mortality (1.75 (1.00 to 3.05)) (increment 10 microg/m(3)). These associations were insensitive to adjustment for traffic noise. There was an excess of cardiovascular mortality in the highest noise category (>65 dB(A)), with elevated risks for IHD (1.15 (0.86 to 1.53)) and heart failure mortality (1.99 (1.05 to 3.79)). After adjustment for black smoke and traffic intensity, noise risk reduced to unity for IHD mortality and was slightly reduced for heart failure mortality. CONCLUSIONS: Associations between black smoke concentrations and traffic intensity on the nearest road with specific cardiovascular causes of death were not explained by traffic noise in this study.

Noise exposure and children's blood pressure and heart rate: the RANCH project.

BACKGROUND: Conclusions that can be drawn from earlier studies on noise and children's blood pressure are limited due to inconsistent results, methodological problems, and the focus on school noise exposure. OBJECTIVES: To investigate the effects of aircraft and road traffic noise exposure on children's blood pressure and heart rate. METHODS: Participants were 1283 children (age 9-11 years) attending 62 primary schools around two European airports. Data were pooled and analysed using multilevel modelling. Adjustments were made for a range of socioeconomic and lifestyle factors. RESULTS: After pooling the data, aircraft noise exposure at school was related to a statistically non-significant increase in blood pressure and heart rate. Aircraft noise exposure at home was related to a statistically significant increase in blood pressure. Aircraft noise exposure during the night at home was positively and significantly associated with blood pressure. The findings differed between the Dutch and British samples. Negative associations were found between road traffic noise exposure and blood pressure, which cannot be explained. CONCLUSION: On the basis of this study and previous scientific literature, no unequivocal conclusions can be drawn about the relationship between community noise and children's blood pressure.

Nutrition and respiratory health in children in six Central and Eastern European countries.

BACKGROUND: The results of studies on the effect of nutrition on respiratory diseases are inconsistent. The role of nutrition in children's respiratory health was therefore analysed within the cross sectional Central European Study on Air Pollution and Respiratory Health (CESAR). METHOD: A total of 20 271 children aged 7-11 were surveyed in six European countries. Respiratory health and food intake were assessed using questionnaires. Associations between four symptoms and nutritional factors were evaluated using logistic regression, controlling for area plus other potential confounders. RESULTS: All symptoms showed initial associations with nutritional factors. Low consumption of fish and of summer and winter fruit were the most consistent predictors. In a fully adjusted model low fish intake remained a significant independent predictor of persistent cough (OR=1.18; 95% CI 1.04 to 1.34), wheeze ever (OR=1.14; 95% CI 1.03 to 1.25) and current wheeze (OR=1.21; 95% CI 1.06 to 1.39) and a weaker predictor of winter cough (OR=1.10; 95% CI 0.99 to 1.23). Low summer fruit intake was a predictor of winter cough (OR=1.40; 95% CI 1.10 to 1.79) and persistent cough (OR=1.35; 95% CI 1.01 to 1.82). Low winter fruit intake was associated with winter cough (OR=1.28; 95% CI 1.09 to 1.51). Associations between symptoms and vegetable intake were inconsistent. Low summer intake was significantly associated with winter cough (OR=1.23; 95% CI 1.03 to 1.47) but, overall, winter intake had inverse associations with both coughs. Associations between winter vegetable intake and wheeze varied considerably between countries. CONCLUSION: A number of associations were found between respiratory symptoms and low intake of fish, fruit and vegetables in children. Low fish intake was the most consistent predictor of poor respiratory health. Fruit and vegetable intake showed stronger associations with cough than with wheeze.

Respiratory symptoms, bronchitis and asthma in children of Central and Eastern Europe.

The multicentre Central European Study of Air Pollution and Respiratory Health (CESAR) aimed to measure the respiratory health of schoolchildren using a standardised questionnaire in six countries of Central and Eastern Europe (CEE), allowing comparisons within this region and with other European countries. A cross-sectional study was conducted in 25 urban areas of Bulgaria, Czech Republic, Hungary, Poland, Romania, and Slovakia in 1996. Parents of 21,743 schoolchildren of age 7-11 yrs completed a questionnaire based on items from the World Health Organization and International Study of Asthma and Allergies in Childhood questions on cough and wheeze symptoms, as well as on diagnoses by doctors. Life-time prevalence of bronchitis was 55.9%, asthma 3.9%, and asthmatic, spastic or obstructive bronchitis 12.3%. In CEE countries the prevalence of bronchitis is higher and prevalence of asthma appears lower than in Western Europe. However, if asthma is defined as a diagnosis of either asthma or asthmatic, spastic or obstructive bronchitis, then its prevalence is comparable to Western Europe, or higher. In this region, within-country variation for most respiratory parameters is less than between-country variation. Between-country comparisons in doctors' diagnoses appear dependent on the choice of definition of asthma. Europe-wide comparisons in prevalence of respiratory symptoms and diagnosis are reported in this study. Some of the East-West difference in asthma prevalence may be attributable to differences in diagnostic practice.

Methodological approaches to the analysis of hierarchical studies of air pollution and respiratory health--examples from the CESAR study. Central European Study on Air pollution and Respiratory Health.

OBJECTIVES: Many studies of air pollution and health are carried out over several geographical areas, and sometimes over several countries. This paper explores three approaches to analysis in such studies: a non hierarchical model, a two-stage analysis, and multilevel modelling. Illustrations are given using a preliminary subset of data from the CESAR study. DESIGN: The Central European Study on Air pollution and Respiratory Health (CESAR) was conducted in 25 areas within six Central European countries, enrolling 20,271 schoolchildren. Pollution averages were calculated for each area. Associations between pollution and health outcomes were estimated under different models. MAIN RESULTS: A regression analysis of log FVC (forced vital capacity) on PM10, ignoring the geographical hierarchy, estimated a significant mean drop in FVC (adjusted for confounders) of 2.2% (95% CI 0.5% to 1.3%), p=0.007, from the area with the lowest PM10 to that with the highest. A multilevel model (mlm), using data for all children, but with random effects at area and country level, estimated a drop of 2.8% (-0.6% to 6.1%), p=0.110. A two-stage analysis (mean log FVC, adjusted for confounders, was estimated for each area using regression, and these means then regressed on PM10) estimated a drop of 2.6% (-0.5% to 5.5%), p=0.101. Simulation exercises showed the non hierarchical method to be very inadequate in the context of the CESAR study, with only half of all 95% confidence intervals for the estimated PM10 slope containing the true value (i.e., that used to create the simulated data). The two-stage and multilevel modelling methods gave results which were substantially better, though both underperformed slightly. All three methods appeared to give unbiased slope estimates. CONCLUSIONS: Acknowledgement of hierarchical structures is essential in statistical inference--standard errors can be substantially incorrect when they are ignored. Multilevel, random-effects models correctly address hierarchical structures, though having few units at higher levels can cause problems in convergence, especially where complex modelling is required. Two-stage analyses, acknowledging hierarchy, provide simple alternatives to random-effects models.

Immune biomarkers in relation to exposure to particulate matter: a cross-sectional survey in 17 cities of Central Europe.

Human population data on air pollution and its effects on the immune system are scarce. A survey was conducted within the framework of the Central European Study of Air Quality and Respiratory Health (CESAR) to measure a panel of immune biomarkers in children of Bulgaria, Czech Republic, Hungary, Poland, Romania, and Slovakia. Seventeen cities were chosen to represent a wide range of exposure to outdoor air pollution. In each, ambient particulate matter of less than 10 microns diameter and less than 2.5 microns diameter (PM10 and PM2.5) were measured with a Harvard impactor. Blood was collected from 366 school children aged 9 to 11 yr between 11 April and 10 May 1996. The percentage of B, total T, CD4+, CD8+, and natural killer (NK) lymphocytes was determined by flow cytometry (Becton Dickinson); total immunoglobulins of class G, M, A and E (IgG, IgM, IgA, and IgE) were measured in serum using nephelometry (Behring). Associations between PM and each log-transformed biomarker concentration were studied by linear regression, in a two-stage model. The yearly average concentrations varied from 41 to 96 micrograms/m3 for PM10 across the 17 study areas, from 29 to 67 micrograms/m3 for PM2.5, and from 12 to 38 micrograms/m3 for PM10-2.5 (coarse). Number of B, CD4+, CD8+, and NK lymphocytes increased with increasing concentration of PM, having adjusted for age, gender, parental smoking, laboratory of analysis, and recent respiratory illness. Differences in lymphocyte number were larger and statistically significant for exposure to PM2.5. Similar results were found when we examined the association between PM and lymphocyte number separately for each laboratory. Total IgG was increased with increasing concentration of PM, significantly in the case of PM2.5. When we repeated the analyses with two other statistical approaches the results did not differ from those reported here. The effect of coarse PM on lymphocyte numbers appears small in comparison to PM2.5. One possible interpretation of our findings is that long-term exposure to airborne particulates leads to inflammation of the airways and activation of the cellular and humoral immune system.

Respiratory health effects of the indoor environment in a population of Dutch children.

The effect of indoor exposure to nitrogen dioxide on respiratory health was studied over a period of 2 yr in a population of nonsmoking Dutch children 6 to 12 yr of age. Lung function was measured at the schools, and information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. Nitrogen dioxide was measured in the homes of all children with Palmes' diffusion tubes. In addition, information on smoking and dampness in the home was collected by questionnaire. There was no relationship between exposure to nitrogen dioxide in the home and respiratory symptoms. Respiratory symptoms were found to be associated with exposure to tobacco smoke and home dampness. There was a weak, negative association between maximal midexpiratory flow (MMEF) and exposure to nitrogen dioxide. FEV1, peak expiratory flow, and MMEF were all negatively associated with exposure to tobacco smoke. Home dampness was not associated with pulmonary function. Lung function growth, measured over a period of 2 yr, was not consistently associated with any of the indoor exposure variables. The development of respiratory symptoms over time was not associated with indoor exposure to nitrogen dioxide. There was a significant association between exposure to environmental tobacco smoke in the home and the development of wheeze. There was also a significant association between home dampness and the development of cough.

Indoor nitrogen dioxide exposure and children's pulmonary function.

Elevated concentrations of nitrogen dioxide (NO2) are produced in the home by the use of unvented gas appliances. In studies on potential health effects of indoor exposure to NO2, exposure has mostly been estimated from the presence or absence of sources like gas cookers in the home. This leads to misclassification of exposure, as NO2 concentrations in the home depend also on source use, ventilation habits, time budgets, etc. The availability of cheap, passive monitoring devices has made it possible to measure indoor concentrations of NO2 directly in health effects studies, albeit with averaging times of one to several days. So far, it has not been evaluated whether this increases the sensitivity of a study to detect health effects of NO2. In this paper, a comparison is made between NO2 sources and weekly average indoor NO2 measurements, as predictors of pulmonary function in a study among children aged 6-12 years. The relationship between exposure and lung functions was found to be generally non-significant in this study. The results further suggested that in this study, measuring indoor NO2 concentrations with passive monitors offered no advantage over the simple use of source presence as exposure variable.

Lung growth of pre-adolescent children.

Lung growth was studied in 420 Dutch children aged 6-11 yrs. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) were measured four times over a 2.5 yr period with a rolling-seal spirometer. In boys, pulmonary function increased with approximately the same velocity at all ages studied. In girls, however, the growth velocities of FVC and FEV1 increased markedly at age 10 yrs, and growth velocities of PEF and MMEF had increased already at age 9 yrs. The minimum pulmonary function growth velocity could not be determined from the available data in boys. In girls, the minimum pulmonary function growth velocities preceded the minimum height growth velocity at the onset of the pubertal growth spurt. All lung function growth rates were significantly associated with the growth rate of height. In girls, the growth rate of FVC was also associated with the weight growth rate. There was also some association between the growth rates of PEF and MMEF and age. In boys, there was a negative association between age and the growth rates of FVC and FEV1, after adjustment for the growth rate of height.

Estimation of maximum expiratory flow-volume variables in children.

Different protocols for pulmonary function testing were evaluated in 611 children, 6-9 years old. Attention was paid to the necessary minimum number of acceptable maneuvers, the necessary maximum number of attempts, and the best of seven different methods for summarizing variables from maximum expiratory flow-volume (MEFV) curves. The results of the study indicate that it is not useful to continue pulmonary function testing after eight attempts. The differences between the results from three or five acceptable maneuvers are not substantial for any method; in children, obtaining three acceptable curves seems sufficient. When flow variables are selected from one acceptable curve, as in the American Thoracic Society (ATS) guidelines, the reproducibility is somewhat less good than in methods in which results of various curves are averaged or selection is made from different curves. The method that has been recommended by the European Community for Coal and Steel for the selection of MEFV variables in teenagers and adults in Europe, was also demonstrated to be suitable for younger children.

Weak associations in environmental epidemiology.

Several suggestions have been made to enhance study designs to strengthen weak associations. Among these are reduction of non-differential misclassification, and restriction of studies to populations with low underlying risk of disease, due to low exposures to other known determinants of the health effect under investigation. To some extent, these suggestions have been put to use in environmental epidemiology, and in this paper, some prospects and problems associated with these attempts are discussed using examples from our own research.

Lung function and respiratory symptoms in pig farmers.

In a pilot study to investigate the health effects of swine confinement work on the respiratory tract pulmonary function tests and a questionnaire for respiratory symptoms were used. Complete data, including qualitative exposure information, were gathered for 132 owners of fattening, breeding, or closed pig farms. All measured pulmonary function values, except the FVC, were on average lower than the reference values of the European Committee for Coal and Steel. There were no significant associations between duration of exposure and pulmonary function. About 28% of the farmers had respiratory or flu-like symptoms during or shortly after confinement work; 14% reported symptoms four to eight hours after work. For the fattening farm the following elements of confinement management were negatively correlated with pulmonary function: fully slatted floor, an automatic feeding system, natural ventilation, and the use of dust masks. A significant association between lung disease of the pigs and pulmonary function of the pig farmers was observed.

Hydroxyproline excretion in schoolchildren and its relationship to measures of indoor air pollution.

The urinary hydroxyproline excretion was investigated in a population of 6- to 9-year-old schoolchildren living in the Netherlands. Early morning samples of urine were collected at the end of a week in which personal and home monitoring for nitrogen dioxide (NO2) was carried out, and in which detailed information on gas appliances and on parental smoking habits was gathered. In addition, the pulmonary function of the children was measured, and their respiratory symptoms were collected using a standardized questionnaire which was completed by the parents. The hydroxyproline concentrations were standardized for urinary creatinine content. The hydroxyproline/creatinine ratio (HOP/C ratio) was found to be unrelated to NO2 exposure. The presence of major NO2-sources in the kitchen, vented and unvented gas-fired waterheaters, was significantly associated with elevated HOP/C ratios, due to a negative relationship with the creatinine concentration. There was a tendency for HOP/C to increase with the amount of tobacco smoked in the presence of a child. Respiratory symptoms and pulmonary function were unrelated to HOP/C. In this population, the urinary HOP/C ratio was not found to be a close correlate of exposure to NO2 or tobacco smoke, and of respiratory symptoms and pulmonary function.

Biological monitoring of acrylonitrile exposure.

A study was made of the excretion pattern of acrylonitrile (AN) in urine of 15 AN-exposed workers. During a 7-day working period with the following 2 days off, the workers delivered all their urines separately. Exposure data, collected by personal monitoring, showed a mean 8-hour TWA value of 0.13 ppm. The excretion of AN in urine (AN(U) ) showed a typical pattern; concentrations peaked at the end or shortly after the end of the workday and decreased rapidly until the beginning of the next workday. A control group of 41 nonexposed workers of the same company showed a significant increase of AN(U) with increasing number of cigarettes smoked. The AN(U) concentrations of the exposed workers however were, despite the low exposure, much higher than those of the controls, both during the workdays and during the days off. Biological monitoring of AN-exposed workers by assessing AN(U) therefore seems a very sensitive exposure evaluation method, especially because it accounts for inhalation as well as skin penetration as routes for entering the body.