Out-of-Hospital Cardiac Arrest and Airborne Fine Particulate Matter: A Case-Crossover Analysis of Emergency Medical Services Data in Indianapolis, Indiana

• Published in: Environmental health perspectives Vol. 116; no. 5; pp. 631 - 636
• Main Authors: Rosenthal, Frank. S., Carney, John P., Olinger, Michael L.
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.05.2008; National Institute of Environmental Health Sciences
• Subjects: Aged; Air Pollutants - adverse effects; Air pollution; Ambulatory medical care; Cardiac arrest; Cardiovascular diseases; Cardiovascular system; Cardiovascular System - physiopathology; Care and treatment; Cross-Over Studies; Emergency medical services; Emergency Service, Hospital - statistics & numerical data; Environmental health; Exposure; Female; Health services; Heart; Heart Arrest - epidemiology; Heart Arrest - etiology; Heart diseases; Humans; Indiana - epidemiology; Male; Middle Aged; Mortality; Out of hospital cardiac arrest; Particle Size; Particulate matter; Patients; Peas; Referents; Services; Time Factors; Indiana; United States; particulate matter; cardiovascular system; out-of-hospital; case-crossover; EMS; air pollution; cardiac arrest; environmental health
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.10757

Background: Previous studies have found particulate matter (PM) < 2.5 μm in aerodynamic diameter $({\rm PM}_{2.5})$ associated with heart disease mortality. Although rapid effects of ${\rm PM}_{2.5}$ exposure on the cardiovascular system have been proposed, few studies have investigated the effect of short-term exposures on out-of-hospital cardiac arrest (OHCA). Objectives: We aimed to determine whether short-term ${\rm PM}_{2.5}$ exposures increased the risk of OHCA and whether risk depended on subject characteristics or presenting heart rhythm. Methods: A case-crossover analysis determined hazard ratios (HRs) for OHCAs logged by emergency medical systems (EMS) versus hourly and daily ${\rm PM}_{2.5}$ exposures at the time of the OHCA and for daily and hourly periods before it. Results: For all OHCAs (n = 1,374), exposures on the day of the arrest or 1-3 days before arrest had no significant effect on the incidence of OHCA. For cardiac arrests witnessed by bystanders (n = 511), OHCA risk significantly increased with ${\rm PM}_{2.5}$ exposure during the hour of the arrest (HR for a $10\text{-}\mu {\rm g}/{\rm m}^{3}$ increase in ${\rm PM}_{2.5}$ exposure = 1.12; 95% confidence interval, 1.01-1.25). For the subsets of subjects who were white, 60-75 years of age, or presented with asystole, OHCA risk significantly increased with ${\rm PM}_{2.5}$ during the hour of the arrest (HRs for a $10\text{-}\mu {\rm g}/{\rm m}^{3}$ increase in ${\rm PM}_{2.5}$ = 1.18, 1.25, or 1.22, respectively; p < 0.05). HR generally decreased as the time lag between ${\rm PM}_{2.5}$ exposure and OHCA increased. Conclusion: The results suggest an acute effect of short-term ${\rm PM}_{2.5}$ exposure in precipitating OHCAs, and a need to investigate further the role of subject factors in the effects of PM on the risk of OHCA.