The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity.

Rationale: Episode analyses of heat waves have documented a comparatively higher impact on mortality than on morbidity (hospital admissions) in European cities. The evidence from daily time series studies is scarce and inconsistent. Objectives: To evaluate the impact of high environmental temperatures on hospital admissions during April to September in 12 European cities participating in the Assessment and Prevention of Acute Health Effects of Weather Conditions in Europe (PHEWE) project. Methods: For each city, time series analysis was used to model the relationship between maximum apparent temperature (lag 0–3 days) and daily hospital admissions for cardiovascular, cerebrovascular, and respiratory causes by age (all ages, 65–74 age group, and 75+ age group), and the city-specific estimates were pooled for two geographical groupings of cities. Measurements and Main Results: For respiratory admissions, there was a positive association that was heterogeneous between cities. For a 1°C increase in maximum apparent temperature above a threshold, respiratory admissions increased by +4.5% (95% confidence interval, 1.9–7.3) and +3.1% (95% confidence interval, 0.8–5.5) in the 75+ age group in Mediterranean and North-Continental cities, respectively. In contrast, the association between temperature and cardiovascular and cerebrovascular admissions tended to be negative and did not reach statistical significance. Conclusions: High temperatures have a specific impact on respiratory admissions, particularly in the elderly population, but the underlying mechanisms are poorly understood. Why high temperature increases cardiovascular mortality but not cardiovascular admissions is also unclear. The impact of extreme heat events on respiratory admissions is expected to increase in European cities as a result of global warming and progressive population aging.

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.

Background: Heat waves and air pollution are both associated with increased mortality. Their joint effects are less well understood. Methods: We explored the role of air pollution in modifying the effects of heat waves on mortality, within the EuroHEAT project. Daily mortality, meteorologic, and air pollution data from nine European cities for the years 1990–2004 were assembled. We defined heat waves by taking both intensity and duration into account. The city-specific effects of heat wave episodes were estimated using generalized estimating equation models, adjusting for potential confounders with and without inclusion of air pollutants (particles, ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide). To investigate effect modification, we introduced an interaction term between heat waves and each single pollutant in the models. Random effects meta-analysis was used to summarize the city-specific results. Results: The increase in the number of daily deaths during heat wave episodes was 54% higher on high ozone days compared with low, among people age 75–84 years. The heat wave effect on high PM₁₀ days was increased by 36% and 106% in the 75–84 year and 85+ year age groups, respectively. A similar pattern was observed for effects on cardiovascular mortality. Effect modification was less evident for respiratory mortality, although the heat wave effect itself was greater for this cause of death. The heat wave effect was smaller (15–30%) after adjustment for ozone or PM₁₀. Conclusions: The heat wave effect on mortality was larger during high ozone or high PM₁₀ days. When assessing the effect of heat waves on mortality, lack of adjustment for ozone and especially PM₁₀ overestimates effect parameters. This bias has implications for public health policy.

Background: Daily air pollution is associated with increased hospital admissions for cardiovascular diseases, but there are few observations on the link with acute myocardial infarction. To evaluate the relation between various urban air pollutants (total suspended particulate, SO₂, CO, NO₂) and hospital admissions for acute myocardial infarction in Rome, Italy, we performed a case-crossover analysis and studied whether individual characteristics act as effect modifiers. Methods: We studied 6531 subjects residing in Rome and hospitalized for a first episode of acute myocardial infarction (International Classification of Diseases, 9^th edition: 410) from January 1995 to June 1997. The following individual information was available: sex, age, date of hospitalization, coexisting illnesses (hypertension, 25%; diabetes, 15%), and cardiac severity (conduction disorders, 6%; cardiac dysrhythmias, 20%; heart failure, 11%). Daily air pollution data were taken from 5 city monitors. We used a time-stratified case-crossover design; control days were the same day of the week as the myocardial infarction occurred, in other weeks of the month. Results: Positive associations were found for total suspended particulate, NO₂ and CO. The strongest and most consistent effect was found for total suspended particulate. The odds ratio (OR) associated with 10 μg/m³ of total suspended particulate over the 0- to 2-day lag was 1.028 (95% confidence interval [CI] = 1.005–1.052). The association with total suspended particulate tended to be stronger among people older than 74 years of age (OR = 1.046; CI = 1.005–1.089), in the warm period of the year (OR = 1.046; CI = 1.008–1.087), and among subjects who had heart conduction disorders (OR = 1.080; CI = 0.987–1.181). Conclusions: The results suggest that air pollution increases the risk of myocardial infarction, especially during the warm season. There was a tendency for a stronger effect among the elderly and people with heart conduction disturbances.

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