Short term effects of air pollution on health: a European approach using epidemiologic time series data: the APHEA protocol

Assessment and prevention of acute health effects of weather conditions in Europe, the PHEWE project: background, objectives, design

BACKGROUND

The project "Assessment and prevention of acute health effects of weather conditions in Europe" (PHEWE) had the aim of assessing the association between weather conditions and acute health effects, during both warm and cold seasons in 16 European cities with widely differing climatic conditions and to provide information for public health policies.

METHODS

The PHEWE project was a three-year pan-European collaboration between epidemiologists, meteorologists and experts in public health. Meteorological, air pollution and mortality data from 16 cities and hospital admission data from 12 cities were available from 1990 to 2000. The short-term effect on mortality/morbidity was evaluated through city-specific and pooled time series analysis. The interaction between weather and air pollutants was evaluated and health impact assessments were performed to quantify the effect on the different populations. A heat/health watch warning system to predict oppressive weather conditions and alert the population was developed in a subgroup of cities and information on existing prevention policies and of adaptive strategies was gathered.

RESULTS

Main results were presented in a symposium at the conference of the International Society of Environmental Epidemiology in Paris on September 6th 2006 and will be published as scientific articles. The present article introduces the project and includes a description of the database and the framework of the applied methodology.

CONCLUSION

The PHEWE project offers the opportunity to investigate the relationship between temperature and mortality in 16 European cities, representing a wide range of climatic, socio-demographic and cultural characteristics; the use of a standardized methodology allows for direct comparison between cities.

Association between air pollution and asthma admission among children in Hong Kong

Objective

To examine the association of air pollutants with hospital admission for childhood asthma in Hong Kong.

Methods

Data on hospital admissions for asthma, influenza and total hospital admissions in children aged ≤18 years at all Hospital Authority hospitals during 1997–2002 were obtained. Data on daily mean concentrations of particles with aerodynamic diameter <10 μm (i. e. PM₁₀) and <2.5 μm (i. e. PM_2.5), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and ozone (O₃) and data on meteorological variables were associated with asthma hospital admissions using Poisson's regression with generalized additive models for correction of yearly trend, temperature, humidity, day-of-week effect, holiday, influenza admissions and total hospital admission. The possibility of a lag effect of each pollutant and the interaction of different pollutants were also examined.

Results

The association between asthma admission with change of NO₂, PM₁₀, PM_2.5 and O₃ levels remained significant after adjustment for multi-pollutants effect and confounding variables, with increase in asthma admission rate of 5.64% (3.21–8.14) at lag 3 for NO₂, 3.67% (1.52–5.86) at lag 4 for PM₁₀, 3.24% (0.93–5.60) at lag 4 for PM_2.5 and 2.63% (0.64–4.67) at lag 2 for O₃. Effect of SO₂ was lost after adjustment.

Conclusion

Ambient levels of PM₁₀, PM_2.5, NO₂ and O₃ are associated with childhood asthma hospital admission in Hong Kong.

Stronger associations between daily mortality and fine particulate air pollution in summer than in winter: evidence from a heavily polluted region in western Europe

BACKGROUND

Numerous studies have shown a strong association between daily mortality and small particulate with a diameter of <10 microm (PM10) air pollution, but the effects of season have not always been well characterised.

AIM

To study the shape of the association between short-term mortality and PM10 across seasons and quintiles of outdoor temperature.

DESIGN, SETTING AND PARTICIPANTS

Daily data on mortality (n = 354 357), outdoor temperature and PM10 in Flanders, Belgium, from January 1997 to December 2003, were analysed across warm versus cold periods of the year (April-September v October-March), with seasons and quintiles of outdoor temperature as possible effect modifiers.

RESULTS

There was a significant (p<0.001) interaction between PM10 and period of the year in relation to mortality. To allow for non-linearity, daily mean PM10 concentrations were categorised into quartiles. Season-specific PM10 quartiles showed a strong and steep linear association between mortality and PM10 in summer and a less linear association in spring and autumn, whereas in winter the association was less strong and mortality was only increased in the highest PM10 quartile. The effect sizes expressed as the percentage increase in mortality on days in the highest season-specific PM(10) quartile versus the lowest season-specific PM10 quartile were 7.8% (95% CI 6.1 to 9.6) in summer, 6.3% (4.7 to 7.8) in spring, 2.2% (0.58 to 3.8) in autumn and 1.4% (0.06 to 2.9) in winter. An analysis by quintiles of temperature confirmed these effect sizes.

CONCLUSION

The short-term effect of particulate air pollution on mortality strongly depends on outdoor temperature, even in a temperate climate.

On the association between daily mortality and air mass types in Athens, Greece during winter and summer

In this study, we examined the short-term effects of air mass types on mortality in Athens, Greece. An objective air mass types classification was used, based on meteorological parameters measured at the surface. Mortality data were treated with generalized additive models (GAM) and extending Poisson regression, using a LOESS smoother to control for the confounding effects of seasonal patterns, adjusting also for temperature, long-term trends, day of the week, and ambient particle concentrations. The introduced air mass classification explains the daily variation of mortality to a statistically significant degree. The highest daily mortality was observed on days characterized by southerly flow conditions for both the cold (increase in relative risk for mortality 9%; with a 95% confidence interval: 3-14%), and the warm period (7%; with a 95% confidence interval: 2-13%) of the year. The northeasterly flow is associated with the lowest mortality. Effects on mortality, independent of temperature, are observed mainly for lag 0 during the cold period, but persist longer during the warm period. Not adjusting for temperature and/or ambient particle levels slightly alters the results, which then reflect the known temperature and particle effects, already reported in the literature. In conclusion, we find that air mass types have independent effects on mortality for both the cold and warm season and may be used to predict weather-related adverse health effects.

Spatiotemporal relationship between particle air pollution and respiratory emergency hospital admissions in Brisbane, Australia

The nature of spatial variation in the relationship between air pollution and health outcomes within a city remains an open and important question. This study investigated the spatial variability of particle matter air pollution and its association with respiratory emergency hospital admissions across six geographic areas in Brisbane, Australia. Data on particles of 10 microm or less in aerodynamic diameter per cubic metre (PM10), meteorological conditions, and daily respiratory emergency hospital admissions were obtained for the period of 1 January 1998 to 31 December 2001. A Poisson generalised linear model was used to estimate the specific effects of PM10 on respiratory emergency hospital admissions for each geographic area. A pooled effect of PM10 was then estimated using a meta-analysis approach for the whole city. The results of this study indicate that the magnitude of the association between particulate matter and respiratory emergency hospital admissions varied across different geographic areas in Brisbane. This relationship appeared to be stronger in areas with heavy traffic. We found an overall increase of 4.0% (95% confidence interval [CI]: 1.1-6.9%) in respiratory emergency hospital admissions associated with an increase of 10 microg /m3 in PM10 in the single pollutant model. The association was weaker but still statistically significant (an increase of 2.6%; 95% CI: 1.0-5.5%) after adjusting for O3, but did not appear to be affected by NO2. The effect estimates of PM10 were generally consistent for three spatial methods used in this study, but appeared to be underestimated if the spatial nature of the data was ignored. Therefore, the spatial variation in the relationship between PM10 and health outcomes needs to be considered when the health impact of air pollution is assessed, particularly for big cities.

Impact of High Temperatures on Mortality

BACKGROUND

Mortality during sustained periods of hot weather is generally regarded as being in excess of what would be predicted from smooth temperature-mortality gradients estimated using standard time-series regression models. However, the evidence for an effect of continuous days of exceptional heat ("heat wave effect") is indirect. In addition, because some interventions may be triggered only during forecasted heat waves, it would be helpful to know what fraction of all heat-related deaths falls during these specific periods and what fraction occurs throughout the remainder of the summer.

METHODS

Extended time-series data sets of daily mortality counts in 3 major European cities (London, 28 years of data; Budapest, 31 years; Milan, 18 years) were examined in relation to hot weather using a generalized estimating equations approach. We modeled temperature and specific heat wave terms using a variety of specifications.

RESULTS

With a linear effect of same-day temperature above an identified threshold, an additional "heat wave" effect of 5.5% was observed in London (95% confidence interval = 2.2 to 8.9), 9.3% in Budapest (5.8 to 13.0), and 15.2% in Milan (5.7 to 22.5). Heat wave effects were reduced slightly when we relaxed the linear assumption and these effects were reduced substantially when temperature was modeled as an average value of lags 0 to 2 days. In London, fewer than half of all heat-related deaths could be attributed to identified heat wave periods. In Milan and Budapest, the fraction was less than one fifth.

CONCLUSIONS

Heat wave effects were apparent in simple time-series models but were reduced in multilag nonlinear models and small when compared with the overall summertime mortality burden of heat. Reduction of the overall heat burden requires preventive measures in addition to those that target warnings and responses uniquely to heat waves.

Ozone air pollution and daily mortality in Genoa, Italy between 1993 and 1996

The association between ozone (O3) and daily mortality was investigated in Genoa, an Italian city characterized by a Mediterranean climate and a high prevalence of elderly inhabitants. The O3 effect, adjusted for long time trend, seasonality and weather, was assessed using Poisson regression modelling, allowing for overdispersion and autocorrelation, and expressed as mean variation percent of daily mortality per 50 microg/m3 increase (MV). Significant MVs for overall (+4.0%) and cardiovascular (+7.2%) mortality were detected at 1-day lag. The effects were stronger in the warmer season (May-October). Similar estimates were found after restricting the analyses to the elderly (>or=75 years). Furthermore, in this group, higher MVs were observed for total mortality at 2-day lag. A statistically significant synergistic effect between O3 and temperature was observed for cardiovascular mortality, particularly in elderly people, with an evident increase in mortality risk above 26 degrees C (MV +30.0% for the whole population and +40.0% for the elderly, respectively). This investigation highlights the importance of taking local climatic and demographic features into account when comparing different time-series studies, and substantiates the influence of photochemical pollution on mortality trends in small urban areas.

GIS approaches for the estimation of residential-level ambient PM concentrations

Spatial estimations are increasingly used to estimate geocoded ambient particulate matter (PM) concentrations in epidemiologic studies because measures of daily PM concentrations are unavailable in most U.S. locations. This study was conducted to a) assess the feasibility of large-scale kriging estimations of daily residential-level ambient PM concentrations, b) perform and compare cross-validations of different kriging models, c) contrast three popular kriging approaches, and d) calculate SE of the kriging estimations. We used PM data for PM with aerodynamic diameter </= 10 microm (PM10) and aerodynamic diameter </= 2.5 microm (PM2.5) from the U.S. Environmental Protection Agency for the year 2000. Kriging estimations were performed at 94,135 geocoded addresses of Women's Health Initiative study participants using the ArcView geographic information system. We developed a semiautomated program to enable large-scale daily kriging estimation and assessed validity of semivariogram models using prediction error (PE) , standardized prediction error (SPE) , root mean square standardized (RMSS) , and SE of the estimated PM. National- and regional-scale kriging performed satisfactorily, with the former slightly better. The average PE, SPE, and RMSS of daily PM10 semivariograms using regular ordinary kriging with a spherical model were 0.0629, -0.0011, and 1.255 microg/m3, respectively ; the average SE of the estimated residential-level PM10 was 27.36 microg/m3. The values for PM2.5 were 0.049, 0.0085, 1.389, and 4.13 microg/m3, respectively. Lognormal ordinary kriging yielded a smaller average SE and effectively eliminated out-of-range predicted values compared to regular ordinary kriging. Semiautomated daily kriging estimations and semivariogram cross-validations are feasible on a national scale. Lognormal ordinary kriging with a spherical model is valid for estimating daily ambient PM at geocoded residential addresses.

Towards a multidisciplinary and integrated strategy in the assessment of adverse health effects related to air pollution: the case study of Cracow (Poland) and asthma

Complex interaction between anthropogenic activities, air quality and human health in urban areas, such as in Cracow sustains the need for the development of an interdisciplinary and integrated risk-assessment methodology. In such purpose, we propose a pilot study performed on asthmatics and based on a combined use of a biomarker, such as metallothionein 2A (MT-2A) in the characterization of human exposure to one or a mixture of pollutants and of Geographical Information Systems (G.I.S.) which integrates climatic and urban anthropogenic parameters in the assessment of spatio-temporal dispersion of air pollutants. Considering global incidence of air pollution on asthma and on peripheral blood lymphocytes MT-2A expression should provide a complementary information on biological risks linked to urban anthropogenic activities. Such study would help for the establishment of a sustainable development in urban areas that can maintain the integrity of air quality and preserve human health.

Air particulate pollution due to bushfires and respiratory hospital admissions in Brisbane, Australia

To examine the impact of bushfire smoke on hospital admission rates for respiratory disease, a time series study was conducted in Brisbane, Australia. Data on particles of 10 microns or less in aerodynamic diameter (PM10) per cubic metre, bushfire events, meteorological conditions, and daily respiratory hospital admissions were obtained for the period of 1 July 1997 to 31 December 2000. A generalized linear model with the negative binomial distribution was used to estimate the effects of bushfire smoke on respiratory hospital admissions. The results of this study show that daily respiratory hospital admission rates consistently increased with increasing levels of PM10 for both bushfire and non-bushfire periods. This relationship appeared stronger during bushfire periods than non-bushfire periods, especially for the current day. The findings suggest that bushfire smoke was statistically significantly associated with an increased risk of respiratory hospital admissions in Brisbane (p < 0.05). The health impact assessment needs to be considered in the control and management of bushfires.

Individual-level modifiers of the effects of particulate matter on daily mortality

Consistent evidence has shown a positive association between particulate matter with an aerodiameter of less than or equal to 10 mum (PM(10)) and daily mortality. Less is known about the modification of this association by factors measured at the individual level. The authors examined this question in a case-crossover study of 20 US cities. Mortality events (1.9 million) were obtained for nonaccidental, respiratory, heart disease, and stroke mortality between 1989 and 2000. PM(10) concentrations were obtained from the US Environmental Protection Agency. The authors examined the modification of the PM(10)-mortality association by sociodemographics, location of death, season, and secondary diagnoses. They found different patterns of PM(10)-mortality associations by gender and age but no differences by race. The level of education was inversely related to the risk of mortality associated with PM(10). PM(10)-related, out-of-hospital deaths were more likely than were in-hospital deaths, as were those occurring during spring/fall versus summer/winter. A secondary diagnosis of diabetes modified the effect of PM(10) for respiratory and stroke mortality. Pneumonia was a positive effect modifier for deaths from all causes and stroke, while secondary stroke modified the effects for all-cause and respiratory deaths. The findings suggest that more attention must be paid to population characteristics to identify greater likelihood of exposures and susceptibility and, as a result, to improve policy making for air pollution standards.

The relationship between changes in daily air pollution and hospitalizations in Perth, Australia 1992-1998: a case-crossover study

A case-crossover study was undertaken to investigate the relationship between daily air pollutant concentrations and daily hospitalizations for selected disease categories in Perth, Western Australia. Daily measurements of particles (measured by nephelometry and PM2.5), photochemical oxidants (measured as ozone), nitrogen dioxide (NO2) and carbon monoxide (CO) concentrations were obtained from 1992 to 1998 via a metropolitan network of monitoring stations. Daily PM2.5 concentrations were estimated using monitored data, modelling and interpolation. Hospital morbidity data for respiratory, cardiovascular (CVD), gastrointestinal (GI) diseases, chronic obstructive pulmonary diseases (COPD) excluding asthma; pneumonia/influenza diseases; and asthma were obtained and categorized into all ages, less than 15 years and greater than 65 years. Gastrointestinal morbidity was used as a control disease. The data were analyzed using conditional logistic regression. The results showed a small number of significant associations for daily changes in particle concentrations, nitrogen dioxide and carbon monoxide for the respiratory diseases, CODP, pneumonia, asthma and CVD hospitalizations. Changes in ozone concentrations were not significantly associated with any disease outcomes. These data provide useful information on the potential health impacts of air pollution in an airshed with very low sulphur dioxide concentrations and lower nitrogen dioxide concentrations commonly found in many other cities.

The association of respiratory syncytial virus infection and influenza with emergency admissions for respiratory disease in London: an analysis of routine surveillance data

BACKGROUND

The importance of respiratory syncytial virus (RSV) infection in adults is not well known, because laboratory testing for RSV infection is not routine. Both RSV infection and influenza are seasonally related, and it is difficult to disentangle one from the other and to disentangle infection from the season and the cold.

METHODS

Emergency hospitalizations for respiratory disease from April 1994 to March 2001 were analyzed in relation to surveillance data on RSV infection and influenza, using Poisson regression models adapted for time series and adjusted for season, outdoor temperature, and other covariates. Age-specific admission rates attributable to the viruses were also estimated.

RESULTS

Most of the crude relationships of emergency admissions of patients with RSV infection were confounded by season and, to a lesser extent, by cold temperatures. After adjustment for all covariates, including influenza, a 10th-90th percentile increase in RSV counts (defined as the daily number of laboratory reports of RSV) was associated with a rate ratio of 1.36 (95% CI, 1.27-1.45) for emergency admissions for respiratory disease in infants. The rate of hospitalization attributable to RSV infection in children aged <1 year was 5 per 1000 infants per year. The association in people > or =65 years old was much smaller (rate ratio, 1.09; 95% CI, 1.04-1.14; attributable rate of hospitalization , 0.7 per 1000 population); but unlike the association in infants, this association became smaller as the lag (interval) between infection and hospital admission became shorter. Admission rates attributable to influenza were highest in the > or =65-year age group (1.1 per 1000 population), but it was very small at younger ages.

CONCLUSIONS

RSV infection appears to be an important determinant of hospitalization in infants in this data set but appears less certain for older persons and requires further investigation.

Seasonal confounding in air pollution and health time-series studies: effect on air pollution effect estimates

A major statistical challenge in air pollution and health time-series studies is to adequately control for confounding effects of time-varying covariates. Daily health outcome counts are most commonly analysed by Poisson regression models, adjusted for overdispersion, with air pollution levels included as a linear predictor and smooth functions for calendar time and weather variables to adjust for time-varying confounders. Various smoothers have been used so far, but the optimal strategy for choosing smoothers and their degree of smoothing remains controversial. In this work, we evaluate the performance of various smoothers with different criteria for choosing the degree of smoothing in terms of bias and efficiency of the air pollution effect estimate in a simulation study. The evaluated approaches were also applied to real mortality data from 22 European cities. The simulation study imitated a multi-city study. Data were generated from a fully parametric model. Model selection methods which optimize prediction may lead to increased biases in the air pollution effect estimate. Minimization of the absolute value of the sum of the partial autocorrelation function of the model's residuals (PACF), as a criterion to choose the degree of smoothness, gave the smallest biases. The penalized splines (PS) method with a large number of effective dfs (e.g. 8-12 per year) could be used as the basic, relatively conservative, analysis whereas the PS and natural splines in combination with PACF could be applied to provide a reasonable range of the effect estimate.

Sensitivity of the estimated air pollution-respiratory admissions relationship to statistical model choice

The objective of this study was to demonstrate the methodological shortcomings of currently available analytical methods for single-city time series data. We analyzed daily Chronic Obstructive Pulmonary Disease (COPD) and daily asthma hospital admissions in Melbourne, Australia from July 1989 to December 1992. Air pollution data comprised nitrogen dioxide, ozone and sulphur dioxide and air particles index consistent with particulates between 0.1 and 1 microm in aerodynamic diameter. Statistical analyses were performed using generalized linear models, generalized additive models, Poisson autoregressive models and transitional regression models. The estimated effect of nitrogen dioxide on COPD hospital admissions was similar across the different statistical models, RR = 1.06 (95% CI 1.01-1.11). Similarly the estimated effect of nitrogen dioxide on asthma hospital admissions was also consistent, RR = 1.05 (95% CI 1.01-1.09). However, the effects of ozone, air particles index and sulphur dioxide were highly sensitive to model specification for both COPD and asthma hospital admissions. In single-city studies of air pollution and respiratory disease, very different conclusions can be drawn from competing models. Furthermore, real time series data have greater complexity than any of the commonly-used existing models allow. Consequently, single-city studies should use several statistical models to demonstrate the stability of estimated effects.

Ambient Air Pollution Is Associated With Increased Risk of Hospital Cardiac Readmissions of Myocardial Infarction Survivors in Five European Cities

Background— Ambient air pollution has been associated with increases in acute morbidity and mortality. The objective of this study was to evaluate the short-term effects of urban air pollution on cardiac hospital readmissions in survivors of myocardial infarction, a potentially susceptible subpopulation.

Methods and Results— In this European multicenter cohort study, 22 006 survivors of a first myocardial infarction were recruited in Augsburg, Germany; Barcelona, Spain; Helsinki, Finland; Rome, Italy; and Stockholm, Sweden, from 1992 to 2000. Hospital readmissions were recorded in 1992 to 2001. Ambient nitrogen dioxide, carbon monoxide, ozone, and mass of particles <10 μm (PM 10 ) were measured. Particle number concentrations were estimated as a proxy for ultrafine particles. Short-term effects of air pollution on hospital readmissions for myocardial infarction, angina pectoris, and cardiac causes (myocardial infarction, angina pectoris, dysrhythmia, or heart failure) were studied in city-specific Poisson regression analyses with subsequent pooling. During follow-up, 6655 cardiac readmissions were observed. Cardiac readmissions increased in association with same-day concentrations of PM 10 (rate ratio [RR] 1.021, 95% CI 1.004 to 1.039) per 10 μg/m 3 ) and estimated particle number concentrations (RR 1.026 [95% CI 1.005 to 1.048] per 10 000 particles/cm 3 ). Effects of similar strength were observed for carbon monoxide (RR 1.014 [95% CI 1.001 to 1.026] per 200 μg/m 3 [0.172 ppm]), nitrogen dioxide (RR 1.032 [95% CI 1.013 to 1.051] per 8 μg/m 3 [4.16 ppb]), and ozone (RR 1.026 [95% CI 1.001 to 1.051] per 15 μg/m 3 [7.5 ppb]). Pooled effect estimates for angina pectoris and myocardial infarction readmissions were comparable.

Conclusions— The results suggest that ambient air pollution is associated with increased risk of hospital cardiac readmissions of myocardial infarction survivors in 5 European cities.

Increased resting heart rate with pollutants in a population based study

BACKGROUND

Air pollution is associated with cardiovascular mortality. Changes in the autonomic nervous system may contribute to cardiac arrhythmias and cardiovascular mortality. This study investigated the relations between air pollutant concentrations of sulphur dioxide (SO(2)), ozone (O(3)), nitric dioxide (NO(2)), and resting heart rate (RHR) in a population based study.

METHODS

A sample of 863 middle aged men and women, living in Toulouse (MONICA centre) area, was randomly recruited. A cross sectional survey on cardiovascular risk factors was carried. RHR was measured twice in a sitting position after a five minute rest. Multivariate analyses with quintiles of RHR were performed using polytomous logistic regression. Models were adjusted for temperature, season, relative humidity, sex, physical activity, blood pressure, C reactive protein, and cardiovascular drugs.

RESULTS

For NO(2), the OR (odds ratio) (95% CI) associated with an increase of 5 microg/m(3) in the current day of medical examination was 1.14 (1.03 to 1.25) in quintile Q5 of RHR compared with Q1, p for trend = 0.003. For SO(2), OR was 1.16 (0.94 to 1.44) in Q5 compared with Q1, p for trend = 0.05, and for O(3), OR was 0.96 (0.91 to 1.01) in Q5 compared with Q1, p for trend = 0.11. No significant association was seen when the daily mean concentration of NO(2), SO(2), and O(3) was considered during the previous day as well as when day lag 2 or 3 was considered. The cumulative concentration (three consecutive days) of O(3) is negatively associated with RHR (p for trend = 0.02).

CONCLUSION

Changes in pulse rate could reflect cardiac rhythm changes and may be part of the pathophysiological link between pollution and cardiovascular mortality.

Air pollution and respiratory drug use in the city of Como, Italy

STUDY OBJECTIVE AND SETTING: Particulate air pollution has a known negative effect on human respiratory health, often studied with hospital admissions, emergency room access, or mortality as health indicators. We evaluate respiratory drug dispensing data as health indicators for the effects of total suspended particles (TSP) air pollution in the city of Como (84,713 inhabitants).

DESIGN

Weekly count of individual patients with respiratory drug dispensed (Cases) and weekly dispensed daily defined doses (DDD) of drugs were modelled with weekly air mean concentrations of TSP using a Poisson regression model adjusted for long-term trends, seasonal variations, calendar variations due to holidays, and weather.

MAIN RESULT

Relative risks (RR) were expressed for a variation from 10th to 90th percentile of TSP (29-92 microg/m3). Weekly aggregation was used in consideration of the complexity of drug dispensing data and potential biases of daily aggregation. For weekly mean concentrations of TSP, RR = 1.082 (95% Confidence level (CI) 1.002-1.169) for Cases and RR = 1.137 (95% CI 1.044-1.238) for DDD.

CONCLUSION

Our study concludes that both Cases and DDD of dispensed respiratory drugs could be useful for epidemiological surveillance of air pollutant health effects. Further investigation may routinely allow health and economics considerations, producing a stimulating new tool for health policy makers.

The effect of particulate air pollution on emergency admissions for myocardial infarction: a multicity case-crossover analysis

Recently, attention has focused on whether particulate air pollution is a specific trigger of myocardial infarction (MI). The results of several studies of single locations assessing the effects of ambient particular matter on the risk of MI have been disparate. We used a multicity case-crossover study to examine risk of emergency hospitalization associated with fine particulate matter (PM) with aerodynamic diameter < 10 microm (PM10) for > 300,000 MIs during 1985-1999 among elderly residents of 21 U.S. cities. We used time-stratified controls matched on day of the week or on temperature to detect possible residual confounding by weather. Overall, we found a 0.65% [95% confidence interval (CI), 0.3-1.0%] increased risk of hospitalization for MI per 10 microg/m3 increase in ambient PM10 concentration. Matching on apparent temperature yielded a 0.64% increase in risk (95% CI, 0.1-1.2%). We found that the effect size for PM10 doubled for subjects with a previous admission for chronic obstructive pulmonary disease or a secondary diagnosis of pneumonia, although these differences did not achieve statistical significance. There was a weaker indication of a larger effect on males but no evidence of effect modification by age or the other diagnoses. We also found that the shape of the exposure-response relationship between MI hospitalizations and PM10 is almost linear, but with a steeper slope at levels of PM10 < 50 microg/m3. We conclude that increased concentrations of ambient PM10 are associated with increased risk of MI among the elderly.

Childhood respiratory infections and hospital admissions for COPD

Background

Chronic Obstructive Pulmonary Disease (COPD) exacerbations are associated with viral infections. We wished to determine if respiratory viral infection of children in the community was associated with hospital admissions of patients with exacerbations of COPD.

Methods

We collected data over a 45-month period from the Northern Ireland Regional Virus Laboratory and from a general hospital in the same locality. We studied the relationship between upper respiratory infections in children and COPD admissions. We also examined the role of school holidays.

Results

Correlations were seen between the frequency of all viral infections in children and the number of adult COPD hospitalizations (P<0.005). Subgroup analysis showed distinct relationships with epidemics of; influenza A (P<0.001), influenza B (P<0.05), adenovirus (P=0.05), respiratory syncytial virus (P<0.005) and hospital admissions of patients with COPD. There were significantly fewer COPD admissions in the week after the start of a school holiday period (P<0.05).

Conclusions

When children are hospitalized with viral respiratory infection there is an associated rise in adult COPD admissions. This suggests exacerbations of COPD are associated with epidemics of respiratory viruses. When children are on school holidays there is a reduction in COPD admissions in the community. This provides further support for respiratory viruses in the pathogenesis of COPD exacerbations.

Traffic air pollution and hospital admission for asthma: a case-control approach in a Turin (Italy) population

OBJECTIVES

This study investigated the relationship between traffic air pollution and asthma, using a case-control design applied to routinely collected data.

METHODS

Subjects resident in Turin during the period 1997-1999 and admitted for asthma were defined as cases; patients admitted for causes other than respiratory diseases or heart diseases were defined as controls. Nitrogen dioxide and total suspended particulate were considered as indicators of traffic air pollution. Statistical analysis were performed, separately for young (0-14 years), adult (15-64 years) and elderly (>64 years) patients, with a logistic regression model; results are expressed as percentage of risk modification for a 10 g/m(3) increase in exposure to pollutants.

RESULTS

The risk of emergency admissions for asthma rose significantly with increased exposure to nitrogen dioxide [2.4%, 95% Confidence Interval: 0.5%; 4.3%], and total suspended particulate [2.3%, 95% Confidence Interval: 1.1%-3.6%]. The significant association was evident, in particular, among young and elderly patients for both pollutants.

CONCLUSION

Using a case-control design both easy to use and manage, the study confirms the significant association between hospital emergency admissions for asthma and exposure to nitrogen dioxide and total suspended particulate pollutants.

Ozone Air Pollution Is Associated With Acute Myocardial Infarction

BACKGROUND

Despite the diversity of the studied health outcomes, types and levels of pollution, and various environmental settings, there is substantial evidence for a positive link between urban air pollution and cardiovascular diseases. The objective of this study was to test the associations between air pollutants and the occurrence of acute myocardial infarction (AMI).

METHODS AND RESULTS

Pollutant concentrations (SO2, NO2, and O3) were measured hourly as part of the automated air quality network. Since 1985, an AMI registry (the Toulouse MONICA Project) has been collecting data in the southwest of France. All cases of AMI and sudden and probable cardiac deaths are recorded for subjects 35 to 64 years of age. We studied the short-term exposure effect of pollution on the risk of AMI (from January 1, 1997, to June 30, 1999) using a case-crossover design method. We performed a conditional logistic regression analysis to calculate relative risks (RRs) and their 95% CIs. After adjustment for temperature, relative humidity, and influenza epidemics, the RRs (for an increase of 5 microg/m3 of O3 concentration) for AMI occurrence were significant for the current-day and 1-day-lag measurements (RR, 1.05; 95% CI, 1.01 to 1.08; P=0.009; and RR, 1.05; 95% CI, 1.01 to 1.09; P=0.007, respectively). Subjects 55 to 64 years of age with no personal history of ischemic heart disease were the most susceptible to develop an AMI (RR, 1.14; 95% CI, 1.06 to 1.23). NO2 and SO2 exposures were not significantly associated with the occurrence of AMI.

CONCLUSIONS

Observational data confirm that short-term O3 exposure within a period of 1 to 2 days is related to acute coronary events in middle-aged adults without heart disease, whereas NO2 and SO2 are not.

Estimating the exposure-response relationships between particulate matter and mortality within the APHEA multicity project

Several studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of theses studies linear nonthreshold relations were assumed. We investigated the exposure-response association between ambient particles and mortality in the 22 European cities participating in the APHEA (Air Pollution and Health--A European Approach) project, which is the largest available European database. We estimated the exposure-response curves using regression spline models with two knots and then combined the individual city estimates of the spline to get an overall exposure-response relationship. To further explore the heterogeneity in the observed city-specific exposure-response associations, we investigated several city descriptive variables as potential effect modifiers that could alter the shape of the curve. We conclude that the association between ambient particles and mortality in the cities included in the present analysis, and in the range of the pollutant common in all analyzed cities, could be adequately estimated using the linear model. Our results confirm those previously reported in Europe and the United States. The heterogeneity found in the different city-specific relations reflects real effect modification, which can be explained partly by factors characterizing the air pollution mix, climate, and the health of the population.

Short-Term Effects of Air Pollution on Total and Cardiovascular Mortality

BACKGROUND

Air pollution is associated with total mortality. This association may be confounded by uncontrolled time-varying risk factors such as influenza epidemics.

METHODS

We analyzed independent data on influenza epidemics from 7 European cities that also had data on mortality associated with particulates (PM10). We used 10 methods to control for epidemics (5 derived from influenza data and 5 from respiratory mortality series) and compared those results with analyses that did not control for these epidemics.

RESULTS

Adjustment for influenza epidemics increased the PM10 effect estimate in most cases (% change in the pooled regression coefficient: -1.9 to 38.9 for total mortality and 1.3 to 25.5 for cardiovascular mortality). A 10-microg/m increase in PM10 concentrations (lag 0-1) was associated with a 0.48% (95% confidence interval=0.27-0.70%) increase in daily mortality unadjusted for influenza epidemics, whereas under the various methods to control for epidemics the increase ranged from 0.45% (0.26-0.69%) to 0.67% (0.46-0.89%). The corresponding figures for cardiovascular mortality were 0.85% (0.53-1.18%) with no adjustment and from 0.86% (0.53-1.19%) to 1.06% (0.74-1.39%) with the methods of control.

CONCLUSIONS

The association between air pollution and mortality is not weakened by control for influenza epidemic irrespective of the method used. To adjust for influenza epidemics, one can use methods based on respiratory mortality counts instead of counts of influenza cases if the latter are not available. However, adjustment for influenza by any method tested did not markedly alter the air pollution effect estimate.

Acute Effects of Ozone on Mortality from the “Air Pollution and Health

In the Air Pollution and Health: A European Approach (APHEA2) project, the effects of ambient ozone concentrations on mortality were investigated. Data were collected on daily ozone concentrations, the daily number of deaths, confounders, and potential effect modifiers from 23 cities/areas for at least 3 years since 1990. Effect estimates were obtained for each city with city-specific models and were combined using second-stage regression models. No significant effects were observed during the cold half of the year. For the warm season, an increase in the 1-hour ozone concentration by 10 mug/m3 was associated with a 0.33% (95% confidence interval [CI], 0.17-0.52) increase in the total daily number of deaths, 0.45% (95% CI, 0.22-0.69) in the number of cardiovascular deaths, and 1.13% (95% CI, 0.62-1.48) in the number of respiratory deaths. The corresponding figures for the 8-hour ozone were similar. The associations with total mortality were independent of SO2 and particulate matter with aerodynamic diameter less than 10 mum (PM10) but were somewhat confounded by NO2 and CO. Individual city estimates were heterogeneous for total (a higher standardized mortality rate was associated with larger effects) and cardiovascular mortality (larger effects were observed in southern cities). The dose-response curve of ozone effects on total mortality during the summer did not deviate significantly from linearity.

Retentissement de la pollution atmosphérique sur la santé

OBJECTIVES

To quantify the short term effects of air pollution on mortality and hospitalisation for cardiovascular or respiratory disorders in the nine French cities (Bordeaux, Le Havre, Lille, Lyon, Marseille, Paris, Rouen, Strasbourg and Toulouse) of the Surveillance Air et Santé program.

METHODS

Data were available on mortality and hospitalisation were available, respectively, from 1990 to 1997 and 1995 to 1999. Exposure data were the concentrations of sulphur dioxide, particles with a diameter of less than or equal to 10 mm, black smoke, nitrogen dioxide, ozone, and carbon monoxide. The analysis assessed the relationships, in each of the cities, between the daily numbers of deaths and hospitalisations and the daily levels of polluting agents, taking into account confounding factors. A combined relative risk was calculated for all the cities. The number of deaths and hospitalisations attributable to air pollution was then estimated for each of the cities, based on the relative risk.

RESULTS

Significant relationships were found for mortality, from whatever cause, and for hospitalisations for respiratory disorders in children aged under 15. If the levels of air pollution were reduced to 10 microg/m3 in the nine cities, 2800 premature deaths and 750 hospitalisations for respiratory disorders in children would be avoided, every year.

CONCLUSION

Today, it is possible to assess the benefits of reducing air pollution in terms of health in the short term. These analyses would provide a sanitary dimension to the strategies for the reduction of urban pollution on local and European level.

Air pollution and the demand for hospital services: a review

Time-series studies published since 1993 on the association between short-term changes in air quality and use of hospital services, including both inpatient and emergency room use, are reviewed. The use of nonparametric analysis, often incorporating generalized additive models (GAMs), has increased greatly since the early 1990s. There have also been three major multi-city studies, which together analyzed data from well over 100 cities in Europe and North America. Various air pollutants, especially ozone (O(3)), particulate matter (PM), nitrogen dioxide (NO(2)) and sulfur dioxide (SO(2)), were generally found to be significantly associated with increased use of hospital services. Ozone tends to have stronger effects in the summer during periods of higher concentrations. Several studies revealed synergistic effects between pollutants such as PM and SO(2). Overall, short-term exposure to air pollutants is found to be an important predictor of increased hospital and emergency room use around the world.

Urban air pollution and asthma in children

This study investigated the relationship between atmospheric pollution and emergency hospital admission for asthma among children resident in Turin in the period 1997-1999, using a case-control design. On the basis of the primary diagnosis, pediatric patients (< 15 years old) resident in Turin and admitted for asthma were defined as cases (n(1) = 1,060); age-matched patients admitted for causes other than respiratory diseases or heart diseases were defined as controls (n(2) = 25,523). Nitrogen dioxide (NO(2) in microg/m(3)) and total suspended particulates (TSP in microg/m(3)) were considered as indicators of urban air pollution; sex and age of patient, seasonality, temperature, humidity, solar radiation, and day of admission were considered as principal confounders. Statistical analyses were performed using simple and multiple logistic regression models; the association between emergency admission for asthma and exposure was shown as percentage of risk modification for a 10 microg/m(3) increment of exposure to each pollutant and relative 95% confidence interval. The number of emergency admissions for respiratory causes rose significantly with increased exposure to each pollutant: 2.8% (95% CI, 0.7-4.9%) and 1.8% (95% CI, 0.3-3.2) for a 10 microg/m(3) increment of exposure to NO(2) and TSP, respectively. A significant association was found between increased number of hospital emergency admissions for respiratory causes and exposure to principal urban pollutants in Turin. The study confirms the results reported for other Italian and European cities, using a case-control design.

Short-term associations between air pollution and respiratory drug sales

STUDY OBJECTIVE

This research was implemented to assess the effect of air pollution on anti-asthmatic, bronchodilator, and cough and cold preparation sales in the city of Rouen (France) based on the Upper Normandy Regional Union of Health Insurance Offices database and the Air Quality Monitoring Network database.

DESIGN

An ecological time-series analysis was performed for a period of 2 years (July 1998-June 2000). Generalized additive model yields to relative risks and 95% confidence interval (CI) estimates were also carried out.

MAIN RESULTS

The 10-day cumulative effect of a 10-microg/m(3) black smoke increase was significantly associated with a 6.2% (95% CI, 2.4-10.1%) increase in the sales of anti-asthmatics and bronchodilators and to a 9.2% (95% CI, 5.9-12.6%) increase in the sales of cough and cold preparation for children aged under 15 years. The cumulative effect of a 10-microg/m(3) increase in SO(2) was associated with an 11.8% (95% CI, 6.7-17.1%) increase in cough and cold preparation sales for children aged under 15 years. The cumulative effect of 10-microg/m(3) increase in NO(2) was associated with an 13.6% (95% CI, 8-18.3%) increase in cough and cold preparation sales for children under 15 years of age.

CONCLUSIONS

The results of this study suggest that an increase in drugs sales was directly related to air pollutant concentration increases in the city of Rouen (France).

Hospital Accident and Emergency burden is unaffected by today's air pollution levels

OBJECTIVES

Fifty years after the London smog incident, the Milan area (Italy) is still experiencing an air pollution emergency every winter, widely reported in the public media, complete with technical and political discussion, and well-studied short-term associations between air pollution and mortality and hospital admissions. The influence of air pollution on the daily activity of an Accident and Emergency Department have rarely been investigated, other than looking at hospital admissions.

METHODS

To assess the possible effects of high air pollution levels we studied 9881 residents requiring care at the hospital Accident and Emergency triage of Vimercate, a city north of Milan with 25 600 inhabitants during one year.

RESULTS

There was no correlation between the number of daily Accident and Emergency admissions and the daily mean of particulate matter less than 10 microm (PM), with a relative risk of 0.97 (95% confidence interval 0.67-1.41) for a 5th to 95th percentile variation of the PM, even after correcting for the day of the week, holidays and climate factors such as temperature and humidity.

CONCLUSION

Air pollution, although still frequently high and relevant to the health of the population, is not easily recognizable on a small scale, such as a single hospital, and does not affect daily Accident and Emergency activities.

Poluição do ar e mortalidade em idosos no Município do Rio de Janeiro: análise de série temporal

Este artigo tem por objetivo investigar a associação entre a poluição do ar por partículas e a mortalidade por doenças cardiovasculares e respiratórias entre idosos no Município do Rio de Janeiro. Informações relativas à mortalidade, a concentrações de partículas totais em suspensão (PTS) e à meteorologia foram obtidas de fontes de dados secundárias. As contagens diárias de óbitos e os níveis médios diários de PTS para os anos de 1990 a 1993 foram analisados em modelos de regressão de Poisson, que incluíam termos para controle de tendências de longo prazo, flutuações sazonais, dia da semana, temperatura e umidade. Para uma elevação dos níveis de PTS do 10º ao 90º percentil (104,7µg/m³), os riscos relativos para mortalidade por doenças cardiovasculares e respiratórias em idosos foram, respectivamente, 1,04 (IC95%: 0,96-1,13) e 1,10 (IC95%: 0,97-1,26). Embora tenha sido observada uma tendência de aumento de risco, as associações não foram estatisticamente significativas, o que pode ser atribuído, em parte, ao pequeno número de medidas de poluição disponíveis no período analisado.

An evaluation of the environmental and health effects of vehicle exhaust catalysts in the UK

Since 1993, all new gasoline-engine automobiles in the United Kingdom have been supplied with three-way vehicle exhaust catalytic converters (VECs) containing platinum, palladium, and rhodium, to comply with European Commission Stage I limits on emissions of regulated pollutants: carbon monoxide, hydrocarbons, and oxides of nitrogen. We conducted a physical and economic evaluation of the environmental and health benefits from a reduction in emissions through this mandated environmental technology against the costs, with reference to urban areas in Great Britain. We made both an ex post assessment--based on available data to 1998--and an ex ante assessment--projected to 2005, the year when full penetration of VECs into the fleet is expected. Substantial health benefits in excess of the costs of VECs were indicated: By 1998 the estimated net societal health benefits were approximately 500 million British pounds, and by 2005 they were estimated to rise to as much as 2 billion British pounds. We also found through environmental surveys that although lead in road dust has fallen by 50% in urban areas, platinum accumulations near roads have risen significantly, up to 90-fold higher than natural background levels. This rapid accumulation of platinum suggests further monitoring is warranted, although as yet there is no evidence of adverse health effects.

The seasonality of total hospitalizations in Ontario by age and gender: a time series analysis

BACKGROUND

Consistent and predictable seasonal fluctuations in hospitalizations have been demonstrated for diverse communicable and non-communicable health conditions. The objective of this study was to examine the seasonal patterns of all hospitalizations by age and gender in order to determine whether the hospital system for a large geographical area was subject to consistent, predictable temporal variations.

METHODS

A retrospective population-based study of approximately 14 million residents of Ontario was conducted to assess temporal patterns in all hospitalizations from April 1, 1988 to March 31, 2000. Time series analysis, using spectral analysis, was conducted to assess seasonal variations and trends over time and to account for autocorrelation.

RESULTS

Conspicuous seasonality in hospitalizations was found in every age group for both sexes with the exception of males between the ages of 20 and 39. The average monthly variability ranged from lows of 15% for the age group 20-29 for both sexes, to highs of 34% in males between 5 and 9 years. For the total population, this represents a 12-year average variability of approximately 20% or 20,000 out of 97,000 hospitalizations. For both sexes, peak hospitalizations typically occurred in the spring and autumn for the youngest and oldest age groups, and in January for the middle age groups.

CONCLUSION

Seasonal factors play an important role in the utilization of hospital services in Ontario. The determinants of this seasonality, which include environmental and social/behavioural factors, are not well understood.

Investigating the dose-response relation between air pollution and total mortality in the APHEA-2 multicity project

BACKGROUND

Several recent studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of these studies linear non-threshold relations were assumed.

AIMS

To investigate the NO2 mortality dose-response association in nine cities participating in the APHEA-2 project using two different methods: the meta-smooth and the cubic spline method.

METHODS

The meta-smooth method developed by Schwartz and Zanobetti is based on combining individual city non-parametric smooth curves; the cubic spline method developed within the APHEA-2 project combines individual city estimates of cubic spline shaped dose-response relations. The meta-smooth method is easier and faster to implement, but the cubic spline method is more flexible for further investigation of possible heterogeneity in the dose-response curves among cities.

RESULTS

In the range of the pollutant common to all cities the two methods gave similar and comparable curves. Using the cubic spline method it was found that smoking prevalence acts as an effect modifier with larger NO2 effects on mortality at lower smoking prevalence.

CONCLUSIONS

The NO2-mortality association in the cities included in the present analysis, could be adequately estimated using the linear model. However, investigation of the city specific dose-response curves should precede the application of linear models.

[Comparison of two methods in the analysis of the short-term effect of air pollution on health]

OBJECTIVE

We compare two methods to analyse the relationship between air pollution and health. One of them (ME) is based on a generalized linear model, while the other one (MN) incorporates a generalized additive model (GAM). Besides the statistical model used, both methods schow additional discrepancies for the type and number of variables used in the control of confounding.

METHOD

An analysis was carried out for each lag of black smoke (0 to 5) and several health indicators from the city of Valencia (Spain) following both methods. Results were compared examining the sequence and the lag of the higher coefficient. The ratio between confidence intervals width and the percent difference in the estimates were also obtained.

RESULTS

The discrepancies in results according to the methodology were small. The sequence shaped and the lag of higher coefficient generally remained invariant. Coefficients were similar (percent difference of MN over ME was not greater than 10%). Confidence intervals were more precise for MN, although the reduction was not very strong (the width ratio was around 90%).

CONCLUSIONS

The short variation of the results guarantees the applicability of both MN and ME methods, although the systematic reduction of the standard error of MN supports its use as a more efficient procedure to control for confounding.

Air pollution and emergency department visits for asthma among Ohio Medicaid recipients, 1991-1996

We examined the effects of nitrogen dioxide (NO(2)), ozone (O(3)), particulate matter of <10 microm aerodynamic diameter (PM(10)), and sulfur dioxide (SO(2)) on asthmatics ages 5-34 years enrolled in Medicaid in Cincinnati, Cleveland, and Columbus, OH (N=5416). Our study period was for the summer months, June-August, from July 1, 1991 to June 30, 1996. We preformed Poisson regression analyses for the number of daily emergency department (ED) visits for asthma in each city and on the aggregate data controlling for time trends and minimum temperature. We found a 12% increased likelihood of an asthma ED visit per 50 microg/m(3) increase in PM(10) in Cleveland [95% confidence interval (CI)=0-27%] and a 35% increase per 50 microg/m(3) increase in SO(2) in Cincinnati (95% CI=9-21%). When data were analyzed for all three cities combined, the risk of an ED visit increased for all pollutant increases and specifically by 12% (95% CI=1-23%) per 50 microg/m(3) increase in SO(2). Attributable risk estimates show a five times greater impact on Cleveland over Cincinnati or Columbus. Between 1991 and 1996, air pollutants in Cincinnati, Cleveland, and Columbus increased ED visits for asthmatics enrolled in Medicaid.

Use of poisson regression and box-jenkins models to evaluate the short-term effects of environmental noise levels on daily emergency admissions in Madrid, Spain

The relationship between environmental factors and hospital admissions has usually been analysed without taking into account the influence of a factor closely related to traffic in big cities, that is, environmental noise levels. We analysed the relationship between environmental noise and emergency admissions, for all causes and specific causes in Madrid (Spain), for the study period 1995-1997, using two statistical methods for the analysis of epidemiological time series data: Poisson autoregressive models and Box Jenkins (ARIMA) methodology. Both methods produce a clear association between emergency admissions for all and specific causes and environmental noise levels. We found very similar results from both methods for all and circulatory causes, but slightly different for respiratory causes. Around 5% of all emergency admissions can be attributed to high noise levels, with a lower figure for specific causes. Current levels of environmental noise have a considerable epidemiological impact on emergency admissions in Madrid. A reduction of environmental noise levels could be accompanied by a possible reduction in the number of emergency admissions.

Short-term effects of particulate air pollution on cardiovascular diseases in eight European cities

STUDY OBJECTIVE

As part of the APHEA project this study examined the association between airborne particles and hospital admissions for cardiac causes (ICD9 390-429) in eight European cities (Barcelona, Birmingham, London, Milan, the Netherlands, Paris, Rome, and Stockholm). All admissions were studied, as well as admissions stratified by age. The association for ischaemic heart disease (ICD9 410-413) and stroke (ICD9 430-438) was also studied, also stratified by age.

DESIGN

Autoregressive Poisson models were used that controlled for long term trend, season, influenza epidemics, and meteorology to assess the short-term effects of particles in each city. The study also examined confounding by other pollutants. City specific results were pooled in a second stage regression to obtain more stable estimates and examine the sources of heterogeneity.

MAIN RESULTS

The pooled percentage increases associated with a 10 micro g/m(3) increase in PM(10) and black smoke were respectively 0.5% (95% CI: 0.2 to 0.8) and 1.1% (95% CI: 0.4 to 1.8) for cardiac admissions of all ages, 0.7% (95% CI: 0.4 to 1.0) and 1.3% (95% CI: 0.4 to 2.2) for cardiac admissions over 65 years, and, 0.8% (95% CI: 0.3 to 1.2) and 1.1% (95% CI: 0.7 to 1.5) for ischaemic heart disease over 65 years. The effect of PM(10) was little changed by control for ozone or SO(2), but was substantially reduced (CO) or eliminated (NO(2)) by control for other traffic related pollutants. The effect of black smoke remained practically unchanged controlling for CO and only somewhat reduced controlling for NO(2).

CONCLUSIONS

These effects of particulate air pollution on cardiac admissions suggest the primary effect is likely to be mainly attributable to diesel exhaust. Results for ischaemic heart disease below 65 years and for stroke over 65 years were inconclusive.

International monitoring for environmental health surveillance

This paper offers an overview of existing international monitoring systems with relevance for environmental health surveillance. Representative monitoring systems are described that: address areas of chronic and acute exposure, and diseases and behavioural effects resulting from human-environment interactions; have an ecosystem focus with perhaps a secondary motivation of ascertaining human health impacts that may result from ecosystem conditions; and that incorporate socio-demographic and economic data that may reflect population health determinants. General conclusions on the state of environmental surveillance systems and suites of indicators reviewed are provided in relation to their utility for the development of a generic environmental health surveillance system. This review indicates, among other things, that no obvious short list of core indicators exists which spans "environmental health" to provide a sufficient set applicable in a global context. Through a summary of challenges and limitations in existing systems and indicator sets, recommendations are provided for the discussion of indicator selection and organization, and of developing general and widely applicable environmental health monitoring and surveillance systems.

International monitoring for environmental health surveillance

This paper offers an overview of existing international monitoring systems with relevance for environmental health surveillance. Representative monitoring systems are described that: address areas of chronic and acute exposure, and diseases and behavioural effects resulting from human-environment interactions; have an ecosystem focus with perhaps a secondary motivation of ascertaining human health impacts that may result from ecosystem conditions; and that incorporate socio-demographic and economic data that may reflect population health determinants. General conclusions on the state of environmental surveillance systems and suites of indicators reviewed are provided in relation to their utility for the development of a generic environmental health surveillance system. This review indicates, among other things, that no obvious short list of core indicators exists which spans "environmental health" to provide a sufficient set applicable in a global context. Through a summary of challenges and limitations in existing systems and indicator sets, recommendations are provided for the discussion of indicator selection and organization, and of developing general and widely applicable environmental health monitoring and surveillance systems.

Ambiente e pulmão

Resumo: O organismo humano está exposto às mais diversas agressões do ambiente; acidentes, agressões físicas, químicas e microbiológicas constituem um permanente risco para o organismo. O aparelho respiratório está particularmente exposto às agressões do ambiente e é freqüentemente sede de alterações de maior ou menor intensidade e gravidade. Revêem-se neste trabalho os efeitos da poluição atmosférica sobre o aparelho respiratório. Definem-se poluição atmosférica, poluição do exterior e dos interiores e poluição primária e secundária. Revêem-se sumariamente os mecanismos de defesa do aparelho respiratório e descrevem-se as ações deletérias dos diferentes poluentes atmosféricos para as vias aéreas: SO2, NO2, CO, O3, aerossóis e partículas. Destaca-se a ação do fumo do tabaco atendendo à sua importância para a saúde. Termina-se tecendo alguns comentários sobre a intervenção que a pneumologia e os pneumologistas devem ter nesta área, chamando a atenção para a comunidade e para as autoridades, para os riscos da poluição para a saúde em geral e, em particular, para o aparelho respiratório.

A longitudinal study of mortality and air pollution for São Paulo, Brazil

We study the effects of various air-pollution variables on the daily death counts for people over 65 years in São Paulo, Brazil, from 1991 to 1993, controlling for meteorological variables. We use a state space model where the air-pollution variables enter via the latent process, and the meteorological variables via the observation equation. The latent process represents the potential mortality due to air pollution, and is estimated by Kalman filter techniques. The effect of air pollution on mortality is found to be a function of the variation in the sulphur dioxide level for the previous 3 days, whereas the other air-pollution variables (total suspended particulates, nitrogen dioxide, carbon monoxide, ozone) are not significant when sulphur dioxide is in the equation. There are significant effects of humidity and up to lag 3 of temperature, and a significant seasonal variation.

The EMECAM project: a multicentre study on air pollution and mortality in Spain: combined results for particulates and for sulfur dioxide

OBJECTIVE

The EMECAM study is a collaborative effort to evaluate the impact of air pollution on mortality in Spain. In this paper the combined results are presented for the short term effects of particulates and sulfur dioxide on both daily mortality for all and for specific causes.

METHODS

The relation between daily mortality for all causes, cardiovascular diseases, and respiratory diseases, and air pollution for particulates (daily concentrations) and SO(2) (24 and 1 hour concentrations) was assessed in 13 Spanish cities for the period 1990-6. With a standardised method, magnitude of association in each city was estimated by Poisson regression in a generalised additive model. Local estimates were obtained from both single and two pollutant analyses. Lastly, combined estimates for each cause and pollutant were obtained.

RESULTS

For combined results, in single pollutant models a 10 microg/m(3) increase in the concentration of the mean of the concurrent and one day lag for black smoke was associated with a 0.8% (95% confidence interval (95% CI) 0.4 to 1.1%) increase in total mortality. The estimates for total suspended particles (TSPs) and particulate matter of aerodynamic diameter <10 microm (PM(10)) and total mortality were slightly lower. The same increase in concentrations of SO(2) was associated with a 0.5% increase in daily deaths. For groups of specific causes, higher estimations were found, specially for respiratory conditions. Peak concentrations of SO(2) showed significant associations with the three groups of mortality. When two pollutant analyses were performed, estimates for particulates, specially for black smoke, did not substantially change. The estimates for daily concentrations of SO(2) were greatly reduced, but, on the contrary, the association with peak concentrations of SO(2) did not show any change.

CONCLUSIONS

There is an association between mortality and pollution through particulates among city populations in Spain. Peak rather than daily concentrations of SO(2) were related to mortality. Results suggest that populations in Spanish cities are exposed to health risks derived from air pollution.

Long-term air pollution indicator assessment: example of black smoke in Bordeaux, France

The aim of the second phase of the Pollution Atmosphérique et Affections Respiratoires Chroniques (PAARC) study, started in 1974, was to compare the long-term mortality between populations living in areas with different air pollution levels. In Bordeaux (France), four different areas were concerned by the study. The black smoke measures were realized between 1974 and 1981. After 1981, the stations set specifically for the study were not used any more. The purpose of this study was to estimate the evolution of air pollution in those areas between 1982 and 1997 using the measures of 12 Association de Prévention de la Pollution Atmosphérique (APPA) stations located in Bordeaux city but not in the PAARC areas. The method used was divided in three phases: a correlation study between the stations of the different networks, a selection of the pertinent stations and the setting up of indicators using the arithmetic means method. Monthly means concentrations were estimated from January 1982 to December 1997. Models showed a decrease in black smoke levels whatever the area. The difference in level from one area to another, existing between the areas in 1974, was still with predicted values in 1997, but less important. Black smoke mean concentration for 1982-1997 was, respectively, 16.4 and 16.2 microg/m3, in areas 1 and 2. It was a little bit higher in area 3 with 18.9 microg/m3. Area 4 still has the highest level with 26.3 microg/m3. To conclude, this method enabled to assess different air pollution levels at different times in the four areas of the PAARC study in Bordeaux. Those levels could be used to study the impact of the air pollution on long-term mortality on populations living in the areas considered.

Methodology in the epidemiological research of respiratory diseases and environmental pollution

There are complex and diverse methodological problems involved in the clinical and epidemiological study of respiratory diseases and their etiological factors. The association of urban growth, industrialization and environmental deterioration with respiratory diseases makes it necessary to pay more attention to this research area with a multidisciplinary approach. Appropriate study designs and statistical techniques to analyze and improve our understanding of the pathological events and their causes must be implemented to reduce the growing morbidity and mortality through better preventive actions and health programs. The objective of the article is to review the most common methodological problems in this research area and to present the most available statistical tools used.

The temporal pattern of mortality responses to air pollution: a multicity assessment of mortality displacement

Although the association between particulate matter and mortality or morbidity is generally accepted, controversy remains about the importance of the association. If it is due solely to the deaths of frail individuals, which are brought forward by only a brief period of time, the public health implications of the association are fewer than if there is an increase in the number of deaths. Recently, other research has addressed the mortality displacement issue in single-city analysis. We analyzed this issue with a distributed lag model in a multicity hierarchic modeling approach, within the Air Pollution and Health: A European Approach (APHEA-2) study. We fit a Poisson regression model and a polynomial distributed lag model with up to 40 days of delay in each city. In the second stage we combined the city-specific results. We found that the overall effect of particulate matter less than 10 microM in aerodynamic diameter (PM10) per 10 microg/m3 for the fourth-degree distributed lag model is a 1.61% increase in daily deaths (95% CI = 1.02-2.20), whereas the mean of PM10 on the same day and the previous day is associated with only a 0.70% increase in deaths (95% CI = 0.43-0.97). This result is unchanged using an unconstrained distributed lag model. Our study confirms that the effects observed in daily time-series studies are not due primarily to short-term mortality displacement. The effect size estimate for airborne particles more than doubles when we consider longer-term effects, which has important implications for risk assessment.

Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China

OBJECTIVE

To investigate the association between ambient concentrations of air pollutants and respiratory and cardiovascular mortalities in Hong Kong.

METHODS

Retrospective ecological study. A Poisson regression of concentrations of daily air pollutants on daily mortalities for respiratory and cardiovascular diseases in Hong Kong from 1995 to the end of 1998 was performed using the air pollution and health: the European approach (APHEA) protocol. The effects of time trend, seasonal variations, temperature, and humidity were adjusted. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), and particulate matter <10 microm in aerodynamic diameter (PM10) were averaged from eight monitoring stations in Hong Kong. Relative risks (RRs) of respiratory and cardiovascular mortalities (per 10 microg/m(3) increase in air pollutant concentration) were calculated.

RESULTS

Significant associations were found between mortalities for all respiratory diseases and ischaemic heart diseases (IHD) and the concentrations of all pollutants when analysed singly. The RRs for all respiratory mortalities (for a 10 microg/m(3) increase in the concentration of a pollutant) ranged from 1.008 (for PM10) to 1.015 (for SO2) and were higher for chronic obstructive pulmonary diseases (COPD) with all pollutants except SO2, ranging from 1.017 (for PM10) to 1.034 (for O3). RRs for IHD ranged from 1.009 (for O3) to 1.028 (for SO2). In a multipollutant model, O3 and SO2 were significantly associated with all respiratory mortalities, whereas NO2 was associated with mortality from IHD. No interactions were detected between any of the pollutants or with the winter season. A dose-response effect was evident for all air pollutants. Harvesting was not found in the short term.

CONCLUSIONS

Mortality risks were detected at current ambient concentrations of air pollutants. The associations with the particulates and some gaseous pollutants when analysed singly were consistent with many reported in temperate countries. PM10 was not associated with respiratory or cardiovascular mortalities in multipollutant analyses.