A time-series study of the health effects of water-soluble and total-extractable metal content of airborne particulate matter
- 1School of Chemistry, University of Edinburgh, Edinburgh, UK
- 2Division of Community Health Sciences, University of Edinburgh, Edinburgh, UK
- 3Centre for Occupational and Environmental Health, University of Manchester, Manchester, UK
- 4Department of Civil Engineering, University of Strathclyde, Glasgow, UK
- Correspondence to Dr Mathew R Heal, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK;
- Accepted 17 March 2009
- Published Online First 17 May 2009
Objectives: To assess whether adverse acute cardiopulmonary health outcomes are associated with concentration of trace metals in airborne particulate matter.
Methods: Daily PM10 and PM2.5 were collected for 1 year in Edinburgh, UK, and the water-soluble and total-extractable content of 11 trace metals determined in each sample. Time series were analysed using generalised additive Poisson regression models, including adjustment for minimum temperature and loess smoothing of trends. Methods were explored of extending the time series of metal concentration in daily PM10 for the previous 7 years using multiple regression of the variation in metal content for the 1 year of measurements and the associated variation in air mass source region and other concurrently-measured potential predictor variables.
Results: The 1 year of direct measurements showed no evidence of significant associations of particle-bound metal concentration with health outcomes beyond that expected by chance. Analysis of the extended time series showed significant positive associations with cardiovascular admissions both for total PM10 and for a number of the metals (eg, Cu, Fe, Ni, V, Zn) but the metal effects were no longer significant after adjusting for PM10.
Conclusions: Within the limitations of the study power, the epidemiological results have not provided evidence for associations between particle-bound metal concentrations and adverse health outcomes that are substantially greater than for total PM. The generally strong correlations between metal and total PM suggest that quantifying independent effects of PM metal exposure on health will be difficult, even using more powerful time series of direct measurements.
Funding Funding was provided by the Chemicals in the Environment joint programme of the UK Department of Health and Department for Environment, Food and Rural Affairs.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.