[Surveillance of short-term effects of urban air pollution on mortality. Results of a feasibility study in 9 French cities]. / Surveillance des effets à court terme de la pollution atmosphérique sur la mortalité en milieu urbain. Résultats d'une étude de faisabilité dans 9 villes françaises.

BACKGROUND: This study aims at quantifying air pollution effects on mortality and at evaluating the feasibility of a standardized epidemiological surveillance system of air pollution in 9 French cities. METHODS: Data collection and analysis followed a standardized protocol. Data pollution depended on the development of local air quality surveillance networks (number of indicators, number of stations.). The Generalised Additive Models (GAM) were used to quantify the association between air pollution and mortality. RESULTS: In the 9 studied areas, associations between all causes, cardiovascular and respiratory mortality, and air pollution indicators were observed. These associations were linear without threshold. Depending on the pollutants, excess in mortality related to an interquartile increase in acid-particulate pollution varied between 0.3 and 3.5% for total mortality, 0.5 and 6.3% for cardiovascular mortality, and between 0.1 and 12% for respiratory mortality. Photochemical air pollution varied between 0.4 and 7.3% for total mortality, 1.4 and 6.7% for cardiovascular mortality, and between 1.7 and 30.4% for respiratory mortality. CONCLUSION: In spite of a standardized common protocol, some disparities, inherent to the local characteristics, were noted (length of time series, numbers of ambient urban stations selected and pollutants available.). Nevertheless, this pilot study showed that multicentric epidemiological monitoring of air pollution effects on health was feasible. Yet, this requires to validate the results obtained through a re-analysis of the mortality data on a longer period of study. It also requires to study the feasibility and the relevance of the use of other health indicators, such as hospital admissions.

Short-term effects of air pollution on mortality in the cities of Rouen and Le Havre, France, 1990-1995.

In this study, the authors examined the short-term effects of ambient air pollution on mortality across 2 French cities: Rouen and Le Havre. In Poisson regression models, which controlled for day-of-week effects, the authors used nonparametric smoothing to control for temporal trend, weather, and influenza epidemics. In Rouen, an interquartile range increase of 60.5-94.1 microg/m3 of ozone was associated with an increase of 4.1% (95% confidence interval = 0.6, 7.8) of total mortality. Daily variations in sulfur dioxide (interquartile range increase = 17.6-36.4 microg/m3) were also associated with an 8.2% increase (95% confidence interval = 0.4, 16.6) in respiratory mortality. An increase of 6.1% (95% confidence interval = 1.5, 10.9) of cardiovascular mortality was also observed with an interquartile range increase of nitrogen dioxide (i.e., 25.3-42.2 microg/m3). With respect to Le Havre, an interquartile range increase in daily levels of sulfur dioxide (11.3-35.6 microg/m3) was associated with an increase of approximately 3% (95% confidence interval = 0.8, 5) of cardiovascular mortality. For particulate matter less than or equal to 13 microm in diameter (interquartile increase = 21.5, 45.4 microg/m3), an increase of 6.2% (95% confidence interval = 0.1, 12.8) was observed. The estimates of pollutant effects and their standard deviations were slightly affected by the degree of smoothing temporal variations in this study. When low collinearity was present, the 2-pollutant models provided acceptable estimates of pollutant effects. They suggested that the ozone effect was independent of the Black Smoke effect, and that the effects of sulfur dioxide and nitrogen dioxide were unlikely to be confounded by ozone concentrations. However, high collinearity leads to large estimates of the pollutant coefficient variances and, therefore, leads to inaccurate estimates of pollutant effects. The analysis of the contributory effects of different pollutant mixtures requires further investigation in those instances in which high collinearity between pollutants is present.

[Short-term relationships between urban atmospheric pollution and respiratory mortality: time series studies]. / Relations à court terme entre la pollution atmosphérique urbaine et la mortalité respiratoire: la place des études temporelles.

Time series studies conducted in the field of air pollution aim at testing and quantifying short-term relations which can exist between daily air pollution levels and daily health effects. The method used for this type of survey has sometimes been misunderstood mainly because individual factors and indoor exposure to air pollutants were not taken into account. The adjustment on these individual confounding factors commonly used in classic epidemiologic studies (case-control studies, cohort studies) is not adequate to times series studies which are based on aggregate data. This is different for those factors that change over time according to the levels of air pollution (meteorological conditions, influenza epidemics, trend of health cases) which, when being analysed, must be taken into account either indirectly through time modelling or directly through non-linear modelling processes. During this last decade, numerous studies using the time series method have been published and have found short-term associations between daily levels of air pollution commonly observed and daily respiratory mortality. The consistency of the numerous results published in the international literature are more arguments in favour of non-confounding short-term relations between air pollution and respiratory mortality.

[The impact of air pollution on health. The "Programme de Surveillance Air et Santé 9 villes" (Air and Health surveillance program in 9 cities)]. / Retentissement de la pollution atmosphérique sur la santé. Le Programme de Surveillance Air et Santé 9 villes.

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.

[Relevance and feasibility of a surveillance system of the effects of atmospheric pollution]. / Pertinence et faisabilité d'un système de surveillance des effets de la pollution atmosphérique.

New regulations on the quality of air together with the epidemiological results obtained in the last 10 years on the short-term effects of air pollution on health have led the InVS to set up a program of epidemiological surveillance in 9 French cities. The first phase of this program was dedicated to the study of feasibility of such a surveillance system. Metrological and health data collection was conducted at both local and national levels in order to obtain significant data in close collaboration with experts of each field. The analysis of the relationship between temporal variations of daily series of the two types of indicators have allowed to obtain dose-response relationships between air pollution and mortality. The organisational and technical feasibility of such a surveillance system was confirmed in the first phase of the program.

August 2003 heat wave in France: risk factors for death of elderly people living at home.

The August 2003 heat wave in France resulted in many thousands of excess deaths particularly of elderly people. Individual and environmental risk factors for death among the community-dwelling elderly were identified. We conducted a case-control survey and defined cases as people aged 65 years and older who lived at home and died from August 8 through August 13 from causes other than accident, suicide, or surgical complications. Controls were matched with cases for age, sex, and residential area. Interviewers used questionnaires to collect data. Satellite pictures provided profiles of the heat island characteristics around the homes. Lack of mobility was a major risk factor along with some pre-existing medical conditions. Housing characteristics associated with death were lack of thermal insulation and sleeping on the top floor, right under the roof. The temperature around the building was a major risk factor. Behaviour such as dressing lightly and use of cooling techniques and devices were protective factors. These findings suggest people with pre-existing medical conditions were likely to be vulnerable during heat waves and need information on how to adjust daily routines to heat waves. In the long term, building insulation and urban planning must be adapted to provide protection from possible heat waves.

Air pollution and respiratory drug sales in the City of Le Havre, France, 1993-1996.

The aim of this study is to evaluate ambulatory respiratory drug sales data as health indicators for the short-term effects of ambient air pollution in the city of Le Havre. Daily respiratory drug sales data were crossed with daily ambient air concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and black smoke (BS) using an autoregressive Poisson regression model adjusting for time trends, seasonal variations, influenza epidemics, and weather. Relative risks (RR) were expressed for an increase of two standard deviations above the mean of each pollutant. Respiratory drug sales were associated with most pollutants studied with lags varying from 1 to 9 days. For daily mean concentrations of BS, RR = 1.037 (95% confidence interval (CI) 1.009-1.066) for lag 1 and RR = 1.052 (95% CI 1.023-1.081) for lag 8. For daily mean concentrations of N02, RR = 1.033 (95% CI 1.001-1.066) for lag 1 and RR = 1.046 (95% CI 1.014-1.079) for lag 8. RR observed with a daily 1 h maximum of SO2 were RR= 1.027 (95% CI 1.004-1.051) for lag 3 and RR= 1.032 (95% CI 1.009-1.056) for lag 9. Our study concludes that ambulatory respiratory drug sales data could be useful for epidemiological surveillance of air pollutant health effects.