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

doi:10.1016/j.puhe.2004.10.007

Public Health

Volume 119, Issue 9, September 2005, Pages 844-850

https://doi.org/10.1016/j.puhe.2004.10.007 Get rights and content

Summary

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 μg/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 (≥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 °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.

Introduction

Ozone (O₃) is one of the main components of photochemical pollution which has become a major concern for public health in recent years.1, 2, 3 Nevertheless, investigations evaluating the short-term effects of O₃ on mortality still remain controversial. A study conducted in 20 US cities failed to find an association between O₃ concentration and mortality from either all causes, cardiovascular (CV) disease or respiratory disease.⁴ In contrast, more recent studies carried out in Hong Kong,⁵ Santiago de Chile⁶ and Montreal (Quebec)⁷ reported a significant correlation between O₃ concentration and short-term mortality. An analysis performed in four European cities (London, Athens, Barcelona and Paris), in the framework of the APHEA project, found a significant association between 1-h maximum O₃ concentration and total daily death counts (mean mortality increase 2.9% per 50 μg/m³ O₃ increase).1, 8 In Italy, the recent MISA study examined data from four cities (Turin, Verona, Bologna and Florence) and demonstrated a significant increase of +1.0% in overall mortality and +1.3% in CV mortality per 10 μg/m³ O₃ increase.⁹

There is general agreement about the greater susceptibility of individuals affected by severe respiratory or CV conditions towards pollution-induced health effects,¹⁰ with air-pollution-related mortality being 2.5–4.1 times higher in patients with congestive heart failure than in the general population.¹¹ Therefore, evaluation of the effects of O₃ pollution in areas characterized by a high prevalence of elderly people assumes particular importance.

Genoa is a northern Italian city with a Mediterranean climate, with 659,000 inhabitants spread over an area of 244 km². The elderly:child ratio (people over 65 years:people under 14 years) is 2.34,¹² i.e. more than two-fold higher than the Italian average (1.09),¹³ and one of the highest in the world. Therefore, epidemiological studies performed on the population of Genoa appear to be promising to contribute to the assessment of the relationship between O₃ pollution and mortality.

Section snippets

Materials and methods

Death counts, weather characteristics and O₃ concentrations refer to the period August 1993–December 1996. Mortality data were drawn from the Liguria Region Mortality Registry. Total mortality excluding accidents (ICD-9 0–799.9) and mortality from CV disease (ICD-9 390.0–459.9) were taken into consideration for the analysis, after exclusion of deaths occurring outside the municipality. Daily mean temperature and relative humidity were calculated by averaging data from three weather-monitoring

Results

Hourly missing values for O₃ concentration were 10.3 and 6.6% for the downtown and eastern stations, respectively.

During the whole study, the daily mean temperature was 15.5 °C (range 4–30 °C) and the 24-h mean O₃ level was 64.3 μg/m³ (Table 1).

During the warmer period, the daily mean temperature was 20.3 °C. The 24-h mean O₃ concentration exceeded the national air quality standard threshold (65 μg/m³) on 443 of 644 days (69%).

During the study period, 27,228 deaths from all causes (daily mean 21.8)

Discussion

This study assessed the effect of O₃ concentration on daily mortality in an Italian city with a high proportion of elderly residents and a sizeable presence of oxidative photochemical air pollutants. Despite the short study period and the small population, a statistically significant association between O₃ and daily mortality was detected for all-cause mortality and CV mortality. This effect was particularly evident at lag 1 during the warm period.

The analyses of standardized residuals of the

Acknowledgements

We thank Dr Cecilia Brescianini, Province of Genoa Environmental Control Centre, for making available O₃ concentrations and weather data, Prof. Annibale Biggeri, University of Florence, Statistics Department, for his precious advice, and Mr Thomas J. Wiley for revising the English. This study was partly supported by the Italian Ministry of University and Scientific and Technological Research (MURST) and local grants (University of Genoa, Italy).

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

Summary

Introduction

Section snippets

Materials and methods

Results

Discussion

Acknowledgements

Environ Res

Toxicol Lett

Short-term effects of ambient oxidant exposure on mortality: a combined analysis within the APHEA project

Am J Epidemiol

Ozone-induced inflammation in the lower airways of human subjects

Am Rev Respir Dis

Fine particulate air pollution and mortality in 20 US cities, 1987–1994

N Engl J Med

Effect of air pollution on daily mortality in Hong Kong

Environ Health Perspect

Effect of the fine fraction of particulate matter versus the coarse mass and other pollutants on daily mortality in Santiago, Chile

Air Waste Manage Assoc

Associations between daily cause-specific mortality and concentrations of ground-level ozone in Montreal, Quebec

Am J Epidemiol

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

J Epidemiol Commun Health

Meta-analysis of the Italian studies on short-term effects of air pollution

Epidemiol Prev

The relationship between urban airborne pollution and short-term mortality: quantitative and qualitative aspects

Eur J Epidemiol

Effects of ambient air pollution on daily mortality in a cohort of patients with congestive heart failure

Epidemiology