Long-term traffic air and noise pollution in relation to mortality and hospital readmission among myocardial infarction survivors

AbstractBackgroundThere is relatively little evidence of health effects of long-term exposure to traffic-related pollution in susceptible populations. We investigated whether long-term exposure to traffic air and noise pollution was associated with all-cause mortality or hospital readmission for myocardial infarction (MI) among survivors of hospital admission for MI.MethodsPatients from the Myocardial Ischaemia National Audit Project database resident in Greater London (n=18,138) were followed for death or readmission for MI. High spatially-resolved annual average air pollution (11 metrics of primary traffic, regional or urban background) derived from a dispersion model (resolution 20m×20m) and road traffic noise for the years 2003–2010 were used to assign exposure at residence. Hazard ratios (HR, 95% confidence interval (CI)) were estimated using Cox proportional hazards models.ResultsMost air pollutants were positively associated with all-cause mortality alone and in combination with hospital readmission. The largest associations with mortality per interquartile range (IQR) increase of pollutant were observed for non-exhaust particulate matter (PM10) (HR=1.05 (95% CI 1.00, 1.10), IQR=1.1μg/m3); oxidant gases (HR=1.05 (95% CI 1.00, 1.09), IQR=3.2μg/m3); and the coarse fraction of PM (HR=1.05 (95% CI 1.00, 1.10), IQR=0.9μg/m3). Adjustment for traffic noise only slightly attenuated these associations. The association for a 5dB increase in road-traffic noise with mortality was HR=1.02 (95% CI 0.99, 1.06) independent of air pollution.ConclusionsThese data support a relationship of primary traffic and regional/urban background air pollution with poor prognosis among MI survivors. Although imprecise, traffic noise appeared to have a modest association with prognosis independent of air pollution