Short-Term Effects of Nitrogen Dioxide on Mortality and Susceptibility Factors in 10 Italian Cities: The EpiAir Study.

BACKGROUND: Several studies have shown an association between nitrogen dioxide (NO2) and mortality. In Italy, the EpiAir multicentric study, "Air Pollution and Health: Epidemiological Surveillance and Primary Prevention," investigated short-term health effects of air pollution, including NO2. OBJECTIVES: To study the individual susceptibility, we evaluated the association between NO2 and cause-specific mortality, investigating individual sociodemographic features and chronic/acute medical conditions as potential effect modifiers. METHODS: We considered 276,205 natural deaths of persons > 35 years of age, resident in 10 Italian cities, and deceased between 2001 and 2005. We chose a time-stratified case-crossover analysis to evaluate the short-term effects of NO2 on natural, cardiac, cerebrovascular, and respiratory mortality. For each subject, we collected information on sociodemographic features and hospital admissions in the previous 2 years. Fixed monitors provided daily concentrations of NO2, particulate matter ≤ 10 µm in aerodynamic diameter (PM10) and ozone (O3). RESULTS: We found statistically significant associations with a 10-µg/m3 increase of NO2 for natural mortality [2.09% for lag 0-5; 95% confidence interval (CI), 0.96-3.24], for cardiac mortality (2.63% for lag 0-5; 95% CI, 1.53-3.75), and for respiratory mortality (3.48% for lag 1-5; 95% CI, 0.75-6.29). These associations were independent from those of PM10 and O3. Stronger associations were estimated for subjects with at least one hospital admission in the 2 previous years and for subjects with three or more specific chronic conditions. Some cardiovascular conditions (i.e., ischemic heart disease, pulmonary circulation impairment, heart conduction disorders, heart failure) and diabetes appeared to confer a strong susceptibility to air pollution. CONCLUSIONS: Our results suggest significant and likely independent effects of NO2 on natural, cardiac, and respiratory mortality, particularly among subjects with specific cardiovascular preexisting chronic conditions and diabetes.

[Environmental indicators in ten Italian cities (2001-2005): the air quality data for epidemiological surveillance]. / Indicatori ambientali in dieci città italiane (2001-2005): i dati di qualità dell'aria per la sorveglianza epidemiologica.

OBJECTIVE: to produce environmental indicators suitable for an epidemiological surveillance in 10 Italian cities part of the EpiAir Project (2001-2005). METHODS: the environmental parameters that correlate to relevant health effects are the particles with diameters less than or equal to 10 micrometers (PM10), the nitrogen dioxide (NO2) and the ozone (O3). The necessary meteorological data are: temperature, relative humidity, barometric pressure and apparent temperature.We have identified some criteria to select monitoring stations and have taken standard methods of calculation to produce environmental indicators starting from the daily data available after closely evaluating the completeness of the existing data. Furthermore, we have checked the homogeneity of the selected data to ensure that it represents the population's exposure. RESULTS: close examination of descriptive statistics shows a critical situation of the considered pollutants. The analysis of the yearly state underlines for PM10 values higher than 40 microg/m3 in the area of Mestre-Venice and in Milan, Turin, Bologna e Taranto. For NO2, values are consistently above 40 microg/m3 in Milan, Turin, Bologna, Florence, Rome and Palermo. For ozone, the concentrations were stable, with the exception of Summer 2003 when we recorded, on average, an increase of 13% compared to the mean value estimated for the ten cities during the study period, especially in Mestre-Venice, Turin and Palermo. CONCLUSIONS: it is important to ensure the consistency of the methods and instruments in environmental monitoring. To evaluate health effects and perform interventions over the longterm, it is therefore fundamental that the data be homogenous, especially during the periodic reorganizations and rationalizations of air quality management. It is also necessary to include daily meteorological data that influence pollutant dispersion and population health status.

[Air pollution and mortality in ten Italian cities. Results of the EpiAir Project]. / Inquinamento atmosferico e mortalità in dieci città italiane. Risultati del Progetto EpiAir.

OBJECTIVE: the relationship between air pollution and mortality has been well established in national and international scientific literature. This study reports the results of the EpiAir Project relative to the effect of air pollution on mortality in 10 Italian cities during 2001-2005. The association between particulate matter (PM10) and gases (nitrogen dioxide, NO2, and ozone, O3), and all natural mortality, as well as cardiac, cerebrovascular and respiratory mortality, is presented. Specific issues have been investigated, such as the latency of the air pollution-mortality effects and the identification of individual demographic characteristics and clinical conditions that result in greater susceptibility to the effects of particulate matter. METHODS: the study population consisted of 276,205 subjects aged 35+ years old, resident in one of the 10 Italian cities studied, which died in the city between 2001-2005. For each subject, information was collected on cause of death, location of death, demographical variables and hospital discharge diagnoses in the previous 2-year period. The statistical analysis was adjusted for the relevant temporal and meteorological factors using the case-crossover approach. The results for ozone are limited to the warm semester (April through September). An analysis of the association between air pollution and mortality was conducted for each city, and the city-specific estimates were meta-analyzed on a second level to obtain a pooled result, and reported inter-city heterogeneity. RESULTS: a short-term effect of PM10 on mortality has been detected for all the groups of causes considered, with latencies ranging from lag 0 for cerebrovascular mortality to lag 0-3 for respiratory mortality. The association between NO2 and mortality displays strong and similar effects for all death causes, with prolonged effects (lag 0-5) for all groups of causes. The results for O3 are similar to those found for NO2, with prolonged latency (lag 0-5) for all causes of death with the exception of cerebrovascular mortality, for which a delayed effect (lag 3-5) was identified. Individual susceptibility factors of the PM10-natural mortality association include age, as elderly subjects are especially vulnerable to the effects of particles. CONCLUSIONS: the main results of the study suggest that the air pollution originated by vehicular traffic is the most relevant environmental problem in Italian cities from a public health viewpoint.