Table 1.

Pearson correlation coefficients (upper right) between daily values for the oxidative potential of water-soluble ${\mathrm{PM}}_{2.5}$ as measured by the DTT assay (${\text{OP}}^{\text{DTT}}$) and daily mean values for other air quality variables, June 2012–April 2013, Atlanta, Georgia.

	${\text{OP}}^{\text{DTT}}$	${\mathrm{PM}}_{2.5}$	$\mathrm{CO}$	$\mathrm{EC}$	${\text{NH}}_4$	${\text{NO}}_2$	${\text{NO}}_3$	${\mathrm{O}}_3$	$\mathrm{OC}$	${\text{SO}}_2$	${\text{SO}}_4$	$\mathrm{Mn}$	$\mathrm{Fe}$	$\mathrm{Cu}$
${\text{OP}}^{\text{DTT}}$	—	0.55	0.46	0.56	0.26	0.27	0.24	0.01	0.51	0.28	0.14	0.42	0.43	0.41
${\mathrm{PM}}_{2.5}$	196	—	0.44	0.65	0.63	0.36	0.14	0.41	0.86	0.24	0.66	0.38	0.62	0.48
$\mathrm{CO}$	196	196	—	0.78	0.11	0.72	0.25	0.02	0.46	0.46	0.08	0.29	0.40	0.45
$\mathrm{EC}$	191	191	191	—	0.23	0.59	0.22	0.07	0.70	0.45	0.21	0.40	0.51	0.50
${\text{NH}}_4$	193	193	193	188	—	0.10	0.42	0.08	0.33	$-0.03$	0.83	0.07	0.31	0.22
${\text{NO}}_2$	196	196	196	191	193	—	0.26	0.15	0.42	0.27	0.09	0.24	0.33	0.39
${\text{NO}}_3$	194	194	194	189	191	194	—	$-0.48$	0.07	0.06	0.08	$-0.01$	$-0.02$	$-0.05$
${\mathrm{O}}_3$	196	196	196	191	193	196	194	—	0.43	$-0.01$	0.31	0.19	0.37	0.28
$\mathrm{OC}$	190	190	190	185	187	190	188	190	—	0.19	0.35	0.39	0.60	0.43
${\text{SO}}_2$	196	196	196	191	193	196	194	196	190	—	0.01	0.22	0.17	0.19
${\text{SO}}_4$	196	196	196	191	193	196	194	196	190	196	—	0.13	0.41	0.27
$\mathrm{Mn}$	158	158	158	155	157	158	156	158	152	158	158	—	0.63	0.38
$\mathrm{Fe}$	157	157	157	154	156	157	155	157	151	157	157	156	—	0.70
$\mathrm{Cu}$	152	152	152	149	151	152	150	152	147	152	152	151	150	—

Note: Only days with ${\text{OP}}^{\text{DTT}}$ measurements were used for these correlations; the lower left section of the table shows the number of days included in each correlation. $\mathrm{CO}$, carbon monoxide; $\mathrm{Cu}$, copper; $\mathrm{EC}$, elemental carbon; $\mathrm{Fe}$, iron; $\mathrm{Mn}$, manganese; ${\text{NH}}_4$, ammonium; ${\text{NO}}_2$, nitrogen dioxide; ${\text{NO}}_3$, nitrate; $\mathrm{OC}$, organic carbon; ${\mathrm{O}}_3$, ozone; ${\mathrm{PM}}_{2.5}$, fine particulate matter; ${\text{SO}}_2$, sulfur dioxide; ${\text{SO}}_4$, sulfate.