The EMECAM protocol: an analysis of the short-term effect of air pollution on mortality. Estudio Multicéntrico Espa?ol sobre la Relación entre la Contaminación Atmosférica u la Mortalidad]

The aim of this study is to Mortality show the protocol of analysis which was set out as part of the EMECAM Project, illustrating the application thereof to the effect of pollution has on the mortality in the city of Valencia. The response variables considered will be the daily deaths rate resulting from all causes, except external ones. The explicative variables are the daily series of different pollutants (black smoke, SO2, NO2, CO, O3). As possible confusion variables, weather factors, structural factors and weekly cases of flu are taken into account. A Poisson regression model is built up for each one of the four deaths series in two stages. In the first stage, a baseline model is fitted using the possible confusion variables. In the second stage, the pollution variables or the time legs thereof are included, controlling the residual autocorrelation by including mortality time lags. The process of fitting the baseline model is as follows: 1) Include the significant sinusoidal terms up to the sixth order. 2) Include the significant temperature or temperature squared terms with the time lags thereof up to the 7th order. 3) Repeat this process with the relative humidity. 4) Add in the significant terms of calendar years, daily tendency and tendency squared. 5) The days of the week as dummy variables are always included in the model. 6) Include the holidays and the significant time lags of up to two weeks of flu. Following the reassessment of the model, each one of the pollutants and the time lags thereof up to the fifth order are proven out. The impact is analyzed by six-month periods, including interaction terms.     

The short-term effects of air pollution on mortality. The results of the EMECAM project in the city of Vigo, 1991-94. Estudio Multicéntrico Espa?ol sobre la Relación entre la Contaminación Atmosférica y la Mortalidad]

BACKGROUND: In the Autonomous Region of Galicia, no study has been made of the impacts of air pollution on human health, despite the fact that several of its major cities have moderate levels of pollution. Therefore, we have considered the need of making this study in the city of Vigo. The main objective of this analysis is that of analyzing the short-term impact of air pollution on the daily death rate for all reasons in the city of Vigo throughout the 1991-1994 period, by using the procedure for analysis set out as part of the EMECAM Project. METHOD: The daily fluctuations in the number of deaths for all causes with the exception of the external ones are listed with the daily fluctuations of sulfur dioxide and particles using Poisson regression models. A non-parametric model is also used in order to better control the confusion variables. RESULTS: Using the Poisson regression model, no significant relationships have been found to exist between the pollutants and the death rate. In the non-parametric model, a relationship was found between the concentration of particles on the day immediately prior to the date of death and the death rate, an effect which remains unchanged on including the autoregressive terms. CONCLUSIONS: Particle-based air pollution is a health risk despite the average levels of this pollutant falling within the air quality guideline levels in the city of Vigo.     

The short-term effects of air pollution on mortality: the results of the EMECAM project in the city of Pamplona, 1991-95. Estudio Multicéntrico Espa?ol sobre la Relación entre la Contaminación Atmosférica y la Mortalidad]

BACKGROUND: To assess the short-term impact of air pollution on the daily death rate in the city of Pamplona. METHOD: Ecological study with a population of 212,000 inhabitants. A time series data analysis is conducted by means of multiple linear regression and Poisson regression, with the daily death rate data, air pollution levels for Particles and SO2, weather parameters of average relative humidity and temperature daily and number of cases weekly of flu for the 1991-1995 period. RESULTS: The average number of deaths daily for non-external causes is that of 4.15 deaths, with a range from zero to 13 deaths. The city of Pamplona has a mean annual temperature of 12.7 degrees C (-2.3 degrees C to 31.6 degrees C) and a relative humidity of 68.5%. In the model, the temperature (with a one-day time lag and a six-day time lag temperature squared) and the humidity (with a one-day time lag) is related to the death rate for all causes. But the death rate for non-external causes is only related in the model with the temperature (one-day time lag, P: 0.035) and five-day time lag with temperature squared (p: 0.028). The timely estimates of the relative particle-related risk show that the highest risk of dying stems from respiratory causes with a relative risk of 1.13. However, none of these relationships is statistically significant. In the case of Sulfur Dioxide, the estimates closely near the zero figure, and none of them is significant. CONCLUSIONS: The Temperature has an impact of the death rate for all causes, both external and non-external, and the relative humidity solely has an impact on the death rate for non-external causes. It has not been possible to prove any influence of the daily environmental pollution levels on the daily death rate.     

The short-term effects of air pollution on mortality. The results of the EMECAM project in Saragossa, 1991-1995. Estudio Multicéntrico Espa?ol sobre la Relación entre la Contaminación Atmosférica y la Mortalidad]

BACKGROUND: To assess the short-term impact of pollution on the respiratory death rate in the city of Saragossa throughout the 1991-1995 period and to pinpoint whether any differences exists in terms of age and time of the year. METHODS: The relationship of daily concentrations of smog and SO2 to the daily deaths due to respiratory diseases (CIE-9 460-486) and chronic lung blockage disease and similar EPOC-EA (490-496) was analyzed using Poisson models in keeping with the EMECAM procedure. Possible differences in the impact on those below and over age 70 and according to the six-month period in question were researched. Relative risks (RR) and 95% confidence, intervals (CI95%) WERE CALCULATED FOR 10 micrograms/m3 rises in pollutant. RESULTS: A relationship was found to exist between the respiratory and smog death rate (RR 1.028 CI95% 1.006-1051), the highest risk being during the six-months period of warm weather. For those individuals over age 70, the relationship remained the same throughout this six-month period and was negative for those individuals under age 70. The RR's for the death rate based on EPOC-EA were, overall, 1.038 (CI95% 1.002-1075) and of 1.068 (CI95%: 1.004-1.137) for the six-month period of warm weather. The SO2 pollution showed a positive relationship to the respiratory death rate for the warm period for all ages, RR 1.093 (CI95%: 1.006-1.187) and for those under age 70 (RR 1.240 CI95%: 1.028-1.496). The impact was not conclusive for the cases of pneumonia. CONCLUSIONS: Low levels of air pollution can have a significant impact on the respiratory death rate, especially among the elderly and during the six-month period of warm weather.     

The short-term effects of air pollution on mortality: the results of the EMECAM project in the city of Huelva, 1993-96. Estudio Multicéntrico Espa?ol sobre la Relación entre la Contaminación Atmosférica y la Mortalidad]

BACKGROUND: The objective of this study was to estimate the relationship between the levels of air pollution and the daily mortality in the city of Huelva for the 1993-1996 period using the EMECAM methodology. METHODS: The number of daily deaths for all causes except external ones, the death rate of those over age 69, due to diseases of the circulatory system and for respiratory diseases were used as rate indicators. Four pollutants--SO2, PM10, NO2 and CO--were analyzed, the daily levels of which were furnished by the air pollution monitoring network in Huelva. Autoregressive Poisson regression models were constructed controlling by tendency, seasonality, temperature, humidity, flue and events out of the ordinary. RESULTS: For the mortality rate for all causes, a significant association impact was found to exist for the NO2 for the entire period (RR10 microgram/m3: 1.0414; CI95%: 1.0047-1.0794) and for the particles (PM10) for the cold half of the year (RR10 microgram/m3: 1.0358; CI95%: 1.007-1.0722). For the mortality in people over age 69, a significant relationship was found to exist for SO2 throughout the entire period (RR10 microgram/m3: 1.0606; CI95%: 1.0020-1.1227). A significant relationship to the mortality from respiratory disease particles (PM10) was found to exist for the cold half of the year (RR10 microgram/m3: 1.1412; IC95%: 1.0300-1.2644). There was no association of contaminants with cardiovascular mortality; also there was no association between levels of CO and mortality indicators. CONCLUSIONS: In Huelva, significant relationships have been found to exist between the current levels of air pollution resulting from particles, SO2 and NO2 and the daily mortality. The impact of these pollutants on the mortality is coherent with scientific literature, although in the case of Huelva, the extremely small number of daily deaths due to its small population and other factors limit the consistency thereof.