Air pollution and age: Do older persons suffer more?

Background: Air quality is known to aggravate cardiopulmonary disease. The aim of this work was to examine the extent to which air pollution, underlying illness, and age influenced 30-day inhospital mortality outcomes. Methods: All emergency medical admissions, between 2002 and 2018, to St. James's Hospital, Dublin, Ireland (113,807 episodes in 58,126 patients) and particulate matter (PM10) level on the day of admission were studied; we determined 30-day mortality outcomes for older (≥70 years) persons and whether outcomes were conditionally dependent on the underlying illness severity or comorbidity score. We employed a logistic multiple variable regression model to calculate PM10influence on the outcome adjusted for other predictors. Results: PM10levels fell over time; the daily median was 15.8 μg/m3 (interquartile ranges [IQR]: 12.1, 21.0) prior to 2010 but 11.5 μg/m3 (IQR: 8.3, 15.7) in subsequent years. A higher admission day PM10level predicted a worse 30-day mortality – odds ratios 1.09 (95% confidence intervals: 1.05, 1.2) for those >70 years, while for younger patients, this was not significant. The influence of PM on outcomes appeared largely confined to older persons; comparisons between increasing PM10quintiles with Q1 median values of 7.5 μg/m3 had a model predicted mortality of 10.8% but 15.0% at Q5 median values of 29.3 μg/m3. An explanation for such difference in outcomes between older and younger may lie in the computed comorbidity and illness severity scores that were quantitatively markedly more severe with advancing age. Conclusion: PM10levels on the day of admission predicted an increased 30-day in hospital mortality risk, with older patients identified to be more susceptible to poor air quality. The disproportionate impact on older persons may be due to their higher concomitant illness severity and comorbidity scores.