Table 2.

Summary Distributions of 3‐Year Average Concentrations of PM_2.5 Chemical Constituents

Variable	Mean	SD	Min	P25	P50	P75	Max
PM2.5, μg/m3	55.23	5.22	26.67	51.60	56.60	59.71	64.41
${\mathrm{NO}}_3^{-}$, μg/m3	9.18	0.55	3.48	8.81	9.22	9.54	12.62
${\mathrm{NH}}_4^{+}$, μg/m3	7.32	0.53	3.82	7.18	7.54	7.64	8.58
OM, μg/m3	21.60	3.38	11.36	18.17	22.18	24.77	27.30
BC, μg/m3	6.58	0.91	1.56	5.78	6.81	7.29	8.66
Cl−, μg/m3	2.27	0.24	0.92	2.07	2.24	2.48	2.85
${\mathrm{SO}}_4^{2-}$, μg/m3	10.66	0.45	7.57	10.48	10.73	11.00	12.19

P₂₅, P₅₀, and P₇₅ denotes 25%, 50%, and 75% percentile separately. BC indicates black carbon; Cl⁻, chloride; ${\mathrm{NH}}_4^{+}$, ammonium; ${\mathrm{NO}}_3^{-}$, nitrate; OM, organic matter; PM_2.5, particulate matter with an aerodynamic diameter ≤2.5 μm; and ${\mathrm{SO}}_4^{2-}$, sulfate.