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Association between long-term exposure to air pollution and specific causes of mortality in Scotland
  1. Christina Yap1,
  2. Iain J Beverland1,
  3. Mathew R Heal2,
  4. Geoffrey R Cohen3,
  5. Chris Robertson4,5,6,
  6. Deborah E J Henderson1,
  7. Neil S Ferguson1,
  8. Carole L Hart7,
  9. George Morris5,8,
  10. Raymond M Agius9
  1. 1Department of Civil Engineering, University of Strathclyde, Glasgow, UK
  2. 2School of Chemistry, University of Edinburgh, Edinburgh, UK
  3. 3Edinburgh, UK
  4. 4Mathematics and Statistics, University of Strathclyde, Glasgow, UK
  5. 5Health Protection Scotland, Glasgow, UK
  6. 6International Prevention Research Institute, Lyon, France
  7. 7Institute of Health and Wellbeing, Public Health, University of Glasgow, Glasgow, UK
  8. 8National Health Service in Scotland, Glasgow, UK
  9. 9Centre for Occupational and Environmental Health, The University of Manchester, Manchester, UK
  1. Correspondence to Dr Iain Beverland, Department of Civil Engineering, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, UK; Iain.Beverland{at}


Objective This study investigated the association between long-term exposure to black smoke (BS) air pollution and mortality in two related Scottish cohorts with 25 years of follow-up.

Methods Risk factors were collected during 1970–1976 for 15331 and 6680 participants in the Renfrew/Paisley and Collaborative cohorts respectively. Exposure to BS during 1970–1979 was estimated by inverse-distance weighted averages of observed concentrations at monitoring sites and by two alternative spatial modelling approaches which included local air quality predictors (LAQP).

Results Consistent BS–mortality associations (per 10 μg m−3 increment in 10-year average BS) were observed in the Renfrew/Paisley cohort using LAQP-based exposure models (all-cause mortality HR 1.10 (95% CI 1.04 to 1.17); cardiovascular HR 1.11 (1.01 to 1.22); ischaemic heart disease HR 1.13 (1.02 to 1.25); respiratory HR 1.26 (1.02 to 1.28)). The associations were largely unaffected by additional adjustment for area-level deprivation category. A less consistent and generally implausible pattern of cause-specific BS–mortality associations was found for inverse-distance averaging of BS concentrations at nearby monitoring sites. BS–mortality associations in the Collaborative cohort were weaker and not statistically significant.

Conclusions The association between mortality and long-term exposure to BS observed in the Renfrew/Paisley cohort is consistent with hypotheses of how air pollution may affect human health. The dissimilarity in pollution–mortality associations for different exposure models highlights the critical importance of reliable estimation of exposures on intraurban spatial scales to avoid potential misclassification bias.

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