Figure 2.

Risk ratio for emergency department (ED) visit outcomes per interquartile range (IQR) of the oxidative potential of water-soluble ${\mathrm{PM}}_{2.5}$ as measured by the DTT assay (${\text{OP}}^{\text{DTT}}$), for (A) lag 0–2 ${\text{OP}}^{\text{DTT}}$ and (B) lag 0 ${\text{OP}}^{\text{DTT}}$, June 2012–April 2013, Atlanta, Georgia. The IQR of ${\text{OP}}^{\text{DTT}}$ is $0.21{\text{nmol}/\text{min}/\mathrm{m}}^3$. Note: CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; CVD, all cardiovascular diseases (combined); IHD, ischemic heart disease; Pneu, pneumonia; RD, all respiratory diseases (combined); URI, upper respiratory infection.