The follow-up of cohorts of adults from more than 20 European centres of the former ECRHS I (1989-1992) investigates long-term effects of exposure to ambient air pollution on respiratory health, in particular asthma and change of pulmonary function. Since PM2.5 is not routinely monitored in Europe, we measured PM2.5 concentrations in 21 participating centres to estimate 'background' exposure in these cities. Winter (November-February), summer (May-August) and annual mean (all months) values of PM2.5 were determined from measuring periods between June 2000 and November 2001. Sampling was conducted for 7 days per month for a year. Annual and winter mean concentrations of PM2.5 vary substantially being lowest in Iceland and highest in centres in Northern Italy. Annual mean concentrations ranged from 3.7 to 44.9μgm-3, winter mean concentrations from 4.8 to 69.2μgm-3, and summer mean concentrations from 3.3 to 23.1μgm-3. Seasonal variability occurred but did not follow the same pattern across all centres. Therefore, ranking of centres varied from summer to winter. Simultaneously, NO2 concentrations were measured using passive sampling tubes. Annual mean NO2 concentrations range from 4.9 to 72.1μgm-3 with similar seasonal variations across centres and constant ranking of centres between seasons. The correlation between annual NO2 and PM2.5 concentrations is fair (Spearman correlation coefficient rs=0.75), but when considered as monthly means the correlation is far less consistent and varies substantially between centres. The range of PM2.5 mass concentrations obtained in ECRHS II is larger than in other current cohort studies on long-term effects of air pollution. This substantial variation in PM2.5 exposure will improve statistical power in future multi-level health analyses and to some degree may compensate for the lack of information on within-city variability. Seasonal means may be used to indicate potential differences in the toxicity across the year. Across ECRHS cities annual NO2 might serve as a surrogate for PM2.5, especially for past exposure assessment, when PM2.5 is not available.
Bibliographical noteFunding Information:
This work forms part of the ECRHS II project, funded by the European Commission as part of their Quality of Life Programme, Environment and Health Key Action (Project number: QLK4-CT-1999-01237) and by the Swiss Federal Agency for Education and Science (BBW-No. 99.0200). N. Künzli, head of air pollution unit of ECRHS had a Swiss National Science Foundation Advanced Scientist Fellowship (PROSPER 32-048922.96), now supported by the NIEHS Southern California Environmental Health Sciences Center P30 ES07048-06. The authors wish to thank the Swedish Heart Lung Foundation, the Vlaamse Milieu Maatschappij (Dr. E. Roekens), the Icelandic Research Council and The National University Hospital Science Fund, the local authorities, and other foundations for their financial support for the equipment.
- Air pollution
- Air quality
- Exposure assessment