A comparison of short-term and long-term air pollution exposure associations with mortality in two cohorts in Scotland

Beverland, I.J., Cohen, G.R., Heal, M.R., Carder, M., Yap, C., Robertson, C., Hart, C.L. and Agius, R.M. (2012) A comparison of short-term and long-term air pollution exposure associations with mortality in two cohorts in Scotland. Environmental Health Perspectives, 120(9), pp. 1280-1285. (doi: 10.1289/ehp.1104509)

Abstract

<p><b>Background:</b> Air pollution-mortality risk estimates are generally larger at longer-term (cf. short-term) exposure time scales.</p> <p><b>Objective:</b> To compare associations between short-term exposure to black smoke (BS) and mortality with long-term exposure-mortality associations in cohort participants, and short-term exposure-mortality associations in the general population from which the cohorts were selected.</p> <p><b>Methods:</b> Short-to-medium term exposure-mortality associations were assessed in 2 cohorts (Renfrew-Paisley & Collaborative) by construction of nested case-control datasets. Comparisons were made with estimates of the effects of long-term exposure (using a multi-level spatio-temporal exposure model and survival analyses); and short-to-medium term exposure in the general population (using time series analyses).</p> <p><b>Results:</b> For the Renfrew-Paisley cohort (15,331 participants), BS exposure-mortality associations were observed in nested case-control analyses that accounted for spatial variations in pollution exposure and individual-level risk factors. These cohort-based associations were consistently greater than associations estimated in time-series analyses using a single monitoring site to represent general population exposure (e.g. 1.8% [95% CI: 0.1-3.4%] versus 0.2% [95% CI: 0.0-0.4%] increases in mortality associated with 10 μg m-3 increases in 3-day lag BS respectively). Exposure-mortality associations were of larger magnitude for longer exposure periods (e.g. 3.4% [95% CI: -0.7-7.7%] and 0.9% [95% CI: 0.3-1.5%] increases in all cause mortality associated with 10 μg m-3 increases in 31-day BS in case-control and time series analyses, respectively; and 9.8% [95% CI: 3.6-16.5%] increase in all-cause mortality associated with 10 μg m-3 increase in average BS for 1970-79 based on survival analysis).</p> <p><b>Conclusions:</b> After adjustment for individual-level exposure and potential confounders, short-term exposure-mortality associations in cohort participants were of greater magnitude than in comparable general population time-series studies, but were substantially lower than long-term exposure-mortality associations, consistent with the possibility of larger, more persistent cumulative effects from long-term exposures.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hart, Dr Carole
• Authors: Beverland, I.J., Cohen, G.R., Heal, M.R., Carder, M., Yap, C., Robertson, C., Hart, C.L., and Agius, R.M.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: Environmental Health Perspectives
• ISSN: 0091-6765
• Published Online: 06 June 2012