Pollution effects on asthmatic children in Europe: the PEACE study.

This thesis is based upon the 'Pollution Effects on Asthmatic Children in Europe (PEACE)' study. The PEACE study is a multi-centre study of the acute effects of particles with a 50% cut-off aerodynamic diameter of 10 µm (PM ₁₀ ), Black Smoke (BS), SO ₂ and NO ₂ on respiratory health of children with chronic respiratory symptoms. The aims of the PEACE study were to obtain comparable data on particle concentrations during winter time in various urban and non urban locations in Europe, to assess the relationship between short term fluctuations in air pollution and short term fluctuations in respiratory health in children with chronic respiratory symptoms, to evaluate if medical characteristics of the subjects are related to differences in response to air pollution and to evaluate if the composition of the particles is related to the response to air pollution.The study was conducted in the winter of 1993-1994 by 14 research centres in Europe. 2010 children, divided over 28 panels in urban and suburban locations were followed during at least two months. Exposure to air pollution was monitored on a daily basis. Health status was monitored by daily Peak Expiratory Flow (PEF) measurements and a symptom diary. The association between respiratory health and air pollution levels was calculated with time series analysis, adjusting for time trends, temperature and day of the week.The difference of particle concentrations across countries appeared to be considerably larger than the difference between the urban and suburban location within countries. PM ₁₀ and BS concentrations in the urban area were on average 22% and 43% higher than the corresponding suburban area concentrations respectively. PM ₁₀ concentrations from all Western and Central European locations were significantly correlated in time. No clear associations between PM ₁₀ , BS, SO ₂ or NO ₂ and morning PEF, evening PEF, prevalence of respiratory symptoms or bronchodilator use could be detected. There were no consistent differences in effect estimates between subgroups based on urban vs. suburban, geographical location or mean levels of PM ₁₀ , BS, SO ₂ and NO ₂ . None of the predefined potentially more sensitive subgroups showed a consistent association between air pollution, PEF and respiratory symptoms. Daily concentrations of most elemental concentrations in PM ₁₀ were not associated with daily variation in PEF or prevalence of respiratory symptoms or bronchodilator use. However, daily iron and silicon concentrations were related to daily phlegm prevalence.No clear relation could be established between changes in PM ₁₀ , BS, SO ₂ or NO ₂ and changes in respiratory health. This lack of response is not in agreement with earlier studies with comparable levels of exposure to particulate matter. Concentrations of iron and silicon in PM ₁₀ were associated with prevalence of phlegm and were a better predictor of health effects than PM ₁₀ mass concentrations