Figure 3. Stratified Analyses Comparing Exposure to Particulate Matter With Diameter of 2.5 μm or Less (PM2.5) and Bystander-Witnessed Out-of-Hospital Cardiac Arrest (OHCAs) of Cardiac Origin With an Initial Nonshockable Rhythm .
Ambient temperature at lag0-1, relative humidity at lag0-1, and incidence of influenza epidemic were included in the model. ECG indicates electrocardiogram; lag0-1 indicates difference in mean PM2.5 concentrations measured on the case day and 1 day before.
aOdds ratio for percent increase for every 10-μg/m3 increase in PM2.5 at lag0-1.
bTotal number of regions was 46, with Okinawa excluded from the West Japan region because of geographic differences (eTable 1 and eFigure 1 in the Supplement).