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Evangelia Samoli,¹ Joel Schwartz,² Bogdan Wojtyniak,³ Giota Touloumi,¹ Claudia Spix,⁴ Frank Balducci,⁵ Sylvia Medina,⁶ Giuseppe Rossi,⁷ Jordi Sunyer,⁸ Ljuba Bacharova,⁹ Hugh Ross Anderson,¹⁰ and Klea Katsouyanni¹

¹Department of Hygiene and Epidemiology, University of Athens, Medical School, Athens, Greece; ²Environmental Epidemiology Program, Harvard School of Public Health, Boston, Massachusetts, USA
³National Institute of Hygiene, Warsaw, Poland
⁴GSF--Forschungszentrum für Umwelt und Gesundheit, Institute für Epidemiologie Postfach, Neuherberg, Germany
⁵Faculté de Medecine, Université de Grenoble, Departement of Public Health, Grenoble, France
⁶Observatoire Regional de la Santé, Paris, France
⁷Institute of Clinical Physiology, National Research Council, Pisa, Italy
⁸Institut Municipal D'Investigacio Medica, Barcelona, Spain
⁹National Centre for Health Promotion, Bratislava, Slovakia
¹⁰Department of Public Health Sciences, St. George's Hospital Medical School, London, United Kingdom

Abstract

Short-term effects of air pollution on daily mortality in eight western and five central-eastern European countries have been reported previously, as part of the APHEA project. One intriguing finding was that the effects were lower in central-eastern European cities. The analysis used sinusoidal terms for seasonal control and polynomial terms for meteorologic variables, but this is a more rigid approach than the currently accepted method, which uses generalized additive models (GAM) . We therefore reanalyzed the original data to examine the sensitivity of the results to the statistical model. The data were identical to those used in the earlier analyses. The outcome was the daily total number of deaths, and the pollutants analyzed were black smoke (BS) and sulfur dioxide (SO₂) . The analyses were restricted to days with pollutant concentration < 200 µg/m³ and < 150 µg/m³ alternately. We used Poisson regression in a GAM model, and combined individual city regression coefficients using fixed and random-effect models. An increase in BS by 50 µg/m³ was associated with a 2.2% and 3.1% increase in mortality when analysis was restricted to days < 200 µg/m³ and < 150 µg/m³, respectively. The corresponding figures were 5.0% and 5.6% for a similar increase in SO₂. These estimates are larger than the ones published previously: by 69% for BS and 55% for SO₂. The increase occurred only in central-eastern European cities. The ratio of western to central-eastern cities for estimates was reduced to 1.3 for BS (previously 4.8) and 2.6 for SO₂ (previously 4.4) . We conclude that part of the heterogeneity in the estimates of air pollution effects between western and central-eastern cities reported in previous publications was caused by the statistical approach used and the inclusion of days with pollutant levels above 150 µg/m³. However, these results must be investigated further. Key words: air pollution, black smoke, generalized additive models, mortality, Poisson regression, sensitivity analysis, sulfur dioxide. Environ Health Perspect 109:349-353 (2001) . [Online 13 March 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/109p349-353samoli/ abstract.html

Address correspondence to K. Katsouyanni, Department of Hygiene and Epidemiology, University of Athens, Medical School, 75 Mikras Asias Str, Athens 115 27, Greece. Telephone: 301-7719725. Fax: 301-7704225. E-mail: kkatsoug@cc.uoa.gr

The APHEA project was supported by the European Commission, DGXII, Environment 1991-94 Programme (contract number EV5V CT92-0202)

Received 8 February 2000 ; accepted 14 November 2000.