High Risk Subgroups Sensitive to Air Pollution Levels Following an Emergency Medical Admission

For three cohorts (the elderly, socially deprived, and those with chronic disabling disease), the relationship between the concentrations of particulate matter (PM ), sulphur dioxide (SO₂), or oxides of nitrogen (NO ) at the time of hospital admission and outcomes (30-day in-hospital mortality) were investigated All emergency admissions (90,423 episodes, recorded in 48,035 patients) between 2002 and 2015 were examined. PM , SO₂, and NO daily levels from the hospital catchment area were correlated with the outcomes for the older admission cohort (>70 years), those of lower socio-economic status (SES), and with more disabling disease. Adjusted for acuity and complexity, the level of each pollutant on the day of admission independently predicted the 30-day mortality: for PM -OR 1.11 (95% CI: 1.08, 1.15), SO₂-1.20 (95% CI: 1.16, 1.24), and NO -1.09 (1.06-1.13). For the older admission cohort (≥70 years), as admission day pollution increased (NO quintiles) the 30-day mortality was higher in the elderly (14.2% vs. 11.3%: < 0.001). Persons with a lower SES were at increased risk. Persons with more disabling disease also had worse outcomes on days with higher admission particulate matter (PM quintiles). Levels of pollutants on the day of admission of emergency medical admissions predicted 30-day hospital mortality.