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Department of Geography

 

Outdoor air pollution, mortality, and hospital admissions from coronary heart disease in Sheffield, UK: a small-area level ecological study

Research Team: Ravi Maheswaran, Robert P. Haining, Paul Brindley, Jane Law, Tim Pearson, Peter R. Fryers, Stephen Wise and Michael J. Campbell

Abstract

Aims: To examine the hypothesis that coronary heart disease mortality and emergency hospital admission rates are higher in areas with higher outdoor air pollution levels.
Methods and results: Modelled nitrogen oxides (NOx), particulate matter (PM10), and carbon monoxide (CO) levels were interpolated to 1030 census enumeration districts using an ecological study design. Results, based on 6857 deaths and 11407 admissions from 1994-98 and a population of 199682 aged 45 years, were adjusted for age, sex, deprivation, and smoking prevalence. Mortality rate ratios were 1.17 (95% CI 1.06-1.29), 1.08 (95% CI 0.96-1.20), and 1.05 (95% CI 0.95-1.16) in the highest relative to the lowest NOx, PM10, and CO quintile categories, respectively. Corresponding admission rate ratios were 1.00 (95% CI 0.90-1.10), 1.01 (95% CI 0.90-1.14), and 0.88 (95% CI 0.79-0.98).
Conclusion: The results are consistent with an excess risk of coronary heart disease mortality in areas with high outdoor NOx, a proxy for traffic-related pollution, but residual confounding cannot be ruled out. If causality were assumed, 6% of coronary heart disease deaths would have been attributable to outdoor NOx, and targeting pollution reduction measures at high pollution areas would be an option for coronary mortality prevention.

Illustrations

pollution-hospitaladmit fig 1

Table 1: Deaths, hospital admissions, and population counts and rates by age and sex for coronary heart disease (Sheffield, UK 1994-98)

pollution-hospitaladmit fig 2

Table 2: Mean values and category limits for modelled (unsmoothed) NOx, PM10, and CO levels, socioeconomic deprivation, smoking prevalence, age and sex standardized mortality, hospital admission rates for coronary heart disease, population counts, and number of CEDs within categories (Sheffield, UK, 1994-98)

pollution-hospitaladmit fig 3

Table 3: Rate ratios for mortality and emergency hospital admissions from coronary heart disease in relation to modeled outdoor air pollution (NOx, PM10, and CO) quintile categories (Sheffield, UK, 1994-98)

Further reading

Maheswaran, R., R. P. Haining, P. Brindley, J. Law, T. Pearson, P. R. Fryers, S. Wise, and M. J. Campbell (2005). “Outdoor Air Pollution, Mortality, and Hospital Admissions from Coronary Heart Disease in Sheffield, UK: A Small-Area Level Ecological Study.” Eur Heart Jo., 26, 2543-2549.