Table 1.

Participant characteristics with intima-media thickness of common carotid artery (${\text{IMT}}_{\text{CCA}}$) and carotid plaque (CP) burden at baseline and during follow-up by study regions. Values provided are $\text{mean}\pm \text{standard}\hspace{0.17em}\text{deviation}$ for continuous variables or number (%) for categorical variables.

Site	Winston-Salem	New York City	Baltimore	St. Paul	Chicago	Los Angeles
${\mathrm{O}}_3$ concentrations (ppb), 2000–2012	$27.0\pm 2.3$	$15.4\pm 1.5$	$23.7\pm 1.8$	$23.0\pm 1.3$	$23.0\pm 1.4$	$19.2\pm 2.1$
Number of participants
Baseline	568	624	435	529	668	568
Follow-up	534	570	383	489	587	481
Follow-up time (years)	$9.1\pm 1.4$	$8.7\pm 2$	$8.7\pm 2$	$9.2\pm 1.2$	$9.2\pm 1.3$	$8.4\pm 2.1$
Outcomes
Mean ${\text{IMT}}_{\text{CCA}}$ at baseline ($\mu \mathrm{m}$)	$783\pm 208$	$744\pm 203$	$773\pm 203$	$765\pm 253$	$725\pm 176$	$766\pm 222$
Increase in ${\text{IMT}}_{\text{CCA}}$ during follow-up ($\mu \mathrm{m}/\text{year}$)	$13\pm 0.6$	$11\pm 0.5$	$12\pm 0.7$	$10\pm 0.7$	$13\pm 0.5$	$11\pm 0.6$
Baseline: CP prevalence, $n$ (%)	293 (53)	275 (44)	187 (44)	280 (54)	308 (46)	237 (43)
Follow-up: CP formation, $n$ (%)	294 (54)	299 (51)	238 (57)	298 (60)	357 (56)	281 (53)
Baseline demographics
Age	$60\pm 9$	$60\pm 10$	$61\pm 9$	$59\pm 10$	$61\pm 9$	$61\pm 10$
Male, $n$ (%)	261 (46)	256 (41)	200 (46)	270 (51)	314 (47)	284 (50)
Race/ethnicity, $n$ (%)
White	284 (50)	131 (21)	248 (57)	312 (59)	307 (46)	62 (11)
Chinese	—	—	—	—	207 (31)	216 (38)
Black	284 (50)	193 (31)	187 (43)	—	154 (23)	74 (13)
Hispanic	—	300 (48)	—	217 (41)	—	216 (38)
Education, $n$ (%)
$\le \text{High}\hspace{0.17em}\text{school}$	142 (25)	256 (41)	105 (24)	185 (35)	94 (14)	267 (47)
Some college/technical	170 (30)	181 (29)	126 (29)	196 (37)	154 (23)	159 (28)
College or graduate	256 (45)	187 (30)	204 (47)	148 (28)	420 (63)	142 (25)
Employment, $n$ (%)	392 (69)	394 (63)	302 (69)	409 (77)	478 (72)	306 (54)
Neighborhood SES index	$\mathrm{-}0.9\pm 4.6$	$0.3\pm 8$	$\mathrm{-}1.3\pm 4.5$	$\mathrm{-}0.1\pm 3.4$	$\mathrm{-}6.3\pm 6.7$	$0.1\pm 6$
Income ($\text{USD}\times 1,000$)	$64\pm 33$	$45\pm 30$	$64\pm 35$	$51\pm 31$	$75\pm 39$	$40\pm 32$
Baseline risk factors
Body mass index (${\text{kg}/\mathrm{m}}^2$)	$29\pm 5$	$28\pm 5$	$30\pm 6$	$29\pm 5$	$26\pm 5$	$27\pm 5$
Smoking status, $n$ (%)
Never	244 (43)	331 (53)	187 (43)	217 (41)	314 (47)	364 (64)
Former	233 (41)	206 (33)	196 (45)	217 (41)	274 (41)	148 (26)
Current	91 (16)	87 (14)	52 (12)	95 (18)	80 (12)	56 (10)
Pack-years smoking	$13\pm 24$	$9\pm 16$	$12\pm 20$	$11\pm 18$	$11\pm 23$	$5\pm 14$
Secondhand smoking, $n$ (%)	351 (62)	281 (45)	198 (45)	331 (63)	354 (53)	178 (31)
Physical activity, $n$ (%)
Q1	128 (23)	146 (23)	89 (21)	106 (20)	121 (18)	178 (31)
Q2	165 (29)	135 (22)	105 (24)	140 (27)	180 (27)	174 (31)
Q3	133 (23)	155 (25)	110 (25)	125 (23)	185 (28)	126 (22)
Q4	142 (25)	188 (30)	131 (30)	158 (30)	182 (27)	90 (16)
Systolic blood pressure (mm Hg)	$131\pm 21$	$122\pm 19$	$126\pm 18$	$120\pm 18$	$122\pm 20$	$125\pm 21$
Diastolic blood pressure (mm Hg)	$74\pm 10$	$72\pm 9$	$71\pm 10$	$70\pm 10$	$72\pm 10$	$71\pm 10$
Hypertension, $n$ (%)a	284 (50)	268 (43)	191 (44)	175 (33)	227 (34)	227 (40)
High-density lipid ($\text{mg}/\text{dL}$)b	$50\pm 15$	$53\pm 15$	$52\pm 15$	$49\pm 14$	$54\pm 16$	$49\pm 14$
Total cholesterol ($\text{mg}/\text{dL}$)b	$190\pm 35$	$194\pm 35$	$192\pm 35$	$200\pm 38$	$195\pm 33$	$193\pm 34$
Statin use, $n$ (%)c	74 (13)	100 (16)	96 (22)	69 (13)	94 (14)	74 (13)
Antihypertensive medication, $n$ (%)c	228 (40)	242 (39)	168 (39)	151 (29)	203 (30)	172 (30)
Diabetes, $n$ (%)d
Normal	453 (80)	487 (78)	338 (78)	420 (79)	547 (82)	383 (67)
Impaired fasting glucose	65 (12)	68 (11)	61 (14)	62 (12)	77 (12)	107 (19)
Diabetic	49 (9)	69 (11)	37 (8)	47 (9)	44 (7)	79 (14)
Family history of premature CVD, $n$ (%)e	168 (30)	154 (25)	138 (32)	170 (32)	166 (25)	113 (20)
Fibrinogen ($\text{mg}/\text{dL}$)	$334\pm 71$	$356\pm 73$	$341\pm 73$	$342\pm 68$	$333\pm 67$	$337\pm 65$
C-reactive protein ($\text{mg}/\text{dL}$)	$4\pm 7$	$3\pm 4$	$4\pm 5$	$4\pm 4$	$3\pm 4$	$3\pm 5$
Creatinine ($\text{mg}/\text{dL}$)	$1\pm 0.3$	$0.9\pm 0.2$	$0.9\pm 0.2$	$0.9\pm 0.2$	$0.9\pm 0.2$	$0.9\pm 0.2$

Outcome, demographic covariates, and risk factors were available for all the participants. Note: —, no data; CVD, cardiovascular disease; SES, socioeconomic status.

^aHypertension was defined as systolic blood pressure $\ge 140\hspace{0.17em}\text{mm}\hspace{0.17em}\text{Hg}$, diastolic blood pressure $\ge 90\hspace{0.17em}\text{mm}\hspace{0.17em}\text{Hg}$, or reported use of antihypertensive medication.

^bPlasma lipid measurements for high-density lipid and total cholesterol.

^cMedication use was defined as any positive report of a statin and/or antihypertensive medication use on the medication inventory for the participants at each of the five clinical exams.

^dDiabetes mellitus was defined as fasting glucose $>125\hspace{0.17em}\text{mg}/\text{dL}$ or the use of hypoglycemic medications. Among those not reporting use of hypoglycemic medications, we defined impaired fasting glucose between 100 and $125\hspace{0.17em}\text{mg}/\text{dL}$ and normal fasting glucose as fasting blood glucose $<100\hspace{0.17em}\text{mg}/\text{dL}$.

^eFamily history of premature cardiovascular disease was defined as myocardial infarction/heart attack, stroke/brain attack, or cardiovascular procedure (coronary bypass or balloon angioplasty) in a female primary relative (parent, sibling, or child) aged $<65\hspace{0.17em}\mathrm{y}$ or a male primary relative aged $<55\hspace{0.17em}\mathrm{y}$.