Table 1.

Summary statistics of ambient air pollutants measured at the Atlanta Jefferson Street monitoring site.

Pollutants	Unit	$n$	$\text{Mean}\pm \text{SD}$	50th (25th, 75th) percentiles	Interquartile range
14 August 1998–15 December 2013
Criteria gases
CO	ppm	5,458	$0.86\pm 0.83$	0.56 (0.36, 1.02)	0.66
${\text{NO}}_2$	ppb	5,321	$37.2\pm 15.2$	35.9 (26.4, 46.3)	20.0
${\text{SO}}_2$	ppb	5,465	$13.4\pm 14.7$	8.1 (3.2, 18.7)	15.5
${\mathrm{O}}_3$	ppb	5,490	$42.1\pm 19.9$	39.6 (27.2, 54.9)	27.7
$\mathrm{P}{\mathrm{M}}_{\mathrm{2}\mathrm{.5}}$
${\mathrm{PM}}_{2.5}$ mass	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,588	$14.46\pm 7.69$	12.81 (8.93, 18.21)	9.28
OC	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,546	$3.67\pm 2.08$	3.22 (2.31, 4.47)	2.16
EC	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,515	$1.26\pm 0.98$	0.98 (0.63, 1.58)	0.95
${\text{NO}}_4$	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,563	$1.39\pm 1.00$	1.10 (0.72, 1.73)	1.01
${\text{NO}}_3$	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,569	$0.81\pm 0.77$	0.55 (0.31, 1.06)	0.75
${\text{SO}}_4$	${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$	5,572	$3.88\pm 2.96$	2.94 (1.88, 4.87)	2.99
Si	$\text{ng}/{\mathrm{m}}^3$	4,932	$94.51\pm 112.37$	68.16 (39.78, 110.79)	71.01
K	$\text{ng}/{\mathrm{m}}^3$	4,932	$63.78\pm 83.88$	50.80 (35.28, 75.54)	40.26
Ca	$\text{ng}/{\mathrm{m}}^3$	4,932	$36.42\pm 29.71$	29.32 (18.29, 44.71)	26.41
Fe	$\text{ng}/{\mathrm{m}}^3$	4,921	$76.51\pm 59.39$	60.29 (39.64, 95.10)	55.47
Zn	$\text{ng}/{\mathrm{m}}^3$	4,880	$11.35\pm 11.16$	8.84 (5.73, 13.31)	7.58
WS Fe	$\text{ng}/{\mathrm{m}}^3$	4,085	$24.22\pm 20.63$	18.67 (10.81, 31.28)	20.46
7 April 2008–15 December 2013
Na	$\text{ng}/{\mathrm{m}}^3$	1,930	$38.86\pm 39.29$	26.03 (14.66, 47.09)	32.43
Al	$\text{ng}/{\mathrm{m}}^3$	1,931	$45.96\pm 59.49$	31.75 (17.37, 56.11)	38.74
Ti	$\text{ng}/{\mathrm{m}}^3$	1,931	$4.47\pm 3.91$	3.62 (2.33, 5.36)	3.03
Cu	$\text{ng}/{\mathrm{m}}^3$	1,916	$5.32\pm 10.40$	3.78 (2.44, 5.68)	3.23
WS V	$\text{ng}/{\mathrm{m}}^3$	805	$0.20\pm 0.19$	0.14 (0.07, 0.26)	0.19
WS Cr	$\text{ng}/{\mathrm{m}}^3$	805	$0.14\pm 0.17$	0.10 (0.06, 0.15)	0.09
WS Mn	$\text{ng}/{\mathrm{m}}^3$	796	$1.20\pm 0.98$	0.94 (0.57, 1.54)	0.96
WS Ni	$\text{ng}/{\mathrm{m}}^3$	805	$0.30\pm 0.68$	0.15 (0.09, 0.25)	0.16
WS Cu	$\text{ng}/{\mathrm{m}}^3$	790	$2.83\pm 4.56$	1.84 (1.10, 3.06)	1.96
WS Zn	$\text{ng}/{\mathrm{m}}^3$	682	$8.99\pm 6.14$	7.32 (4.69, 11.16)	6.47
WS As	$\text{ng}/{\mathrm{m}}^3$	805	$0.68\pm 0.53$	0.56 (0.36, 0.80)	0.44
WS Se	$\text{ng}/{\mathrm{m}}^3$	805	$0.72\pm 0.59$	0.55 (0.33, 0.92)	0.59
WS Cd	$\text{ng}/{\mathrm{m}}^3$	805	$0.08\pm 0.08$	0.06 (0.04, 0.09)	0.05
WS Ba	$\text{ng}/{\mathrm{m}}^3$	805	$3.24\pm 3.23$	2.45 (1.36, 4.10)	2.74
WS Pb	$\text{ng}/{\mathrm{m}}^3$	803	$1.39\pm 2.98$	0.87 (0.56, 1.42)	0.86

Note: Criteria gases were measured daily, including 1-h maximum carbon monoxide (CO), 1-h maximum nitrogen dioxide (${\text{NO}}_2$), 1-h maximum sulfur dioxide (${\text{SO}}_2$), and 8-h maximum ozone (${\mathrm{O}}_3$). ${\mathrm{PM}}_{2.5}$ and its major components, including organic carbon (OC), elemental carbon (EC), ammonium (${\text{NH}}_4$), nitrate (${\text{NO}}_3$), and sulfate (${\text{SO}}_4$), were measured daily using filter-based 24-h integrated Federal Reference Methods. Total elemental concentrations of ${\mathrm{PM}}_{2.5}$ metals and metalloids, including titanium (Ti), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), aluminum (Al), lead (Pb), silicon (Si), calcium (Ca), sodium (Na), and potassium (K), were analyzed from the daily ${\mathrm{PM}}_{2.5}$ filters using X-ray fluorescence. Water-soluble concentrations of ${\mathrm{PM}}_{2.5}$ metals, including water-soluble vanadium (WS V), water-soluble chromium (WS Cr), water-soluble manganese (WS Mn), water-soluble iron (WS Fe), water-soluble nickel (WS Ni), and water-soluble copper (WS Cu), were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES) during 14 August 1998–6 April 2008 and using inductively coupled plasma mass spectrometry (ICP-MS) starting on 7 April 2008. Water-soluble zinc (WS Zn), water-soluble cadmium (WS Cd), water-soluble lead (WS Pb), water-soluble selenium (WS Se), water-soluble arsenic (WS As), water-soluble barium (WS Ba), and water-soluble lanthanum (WS La) were reported starting on 7 April 2008 from ICP-MS analyses. All water-soluble measures were available daily before 2009 and one-in-three days after 2009.