Table 1.
Summary statistics of overall study sample, and by quartile of PM2.5 exposure.
| PM2.5 quartile (μg/m3)
| |||||
|---|---|---|---|---|---|
| 6.5–12.1 N=4,282 |
12.2–13.6 N=4,282 |
13.6–14.8 N=4,283 |
14.8–20.8 N=4,279 |
Combined N=17,126 |
|
| Age (years) | 64 (58,71) | 63 (57,71) | 63 (57,70) | 63 (57,70) | 63 (57,71) |
| Blacks | 32.6% (1,394) |
40.4% (1,728) | 46.2% (1,980) |
51.5% (2,205) |
42.7% (7,307) |
| Women | 54.5% (2,332) |
58.5% (2,505) | 59.2% (2,536) |
58.8% (2,518) |
57.8% (9,891) |
| High risk for CHD (≥10%) | 33.7% (1,443) |
34.2% (1,463) | 34.8% (1,489) |
34.5% (1,475) |
34.3% (5,870) |
| Education level | |||||
| Less than high school | 8.5% (366) | 12.5% (535) | 10.9% (467) |
10.4% (446) | 10.6% (1,814) |
| High school graduate | 21.7% (929) | 26.4% (1,130) | 26.9% (1,150) |
25.0% (1,069) |
25.0% (4,278) |
| Some college | 26.6% (1,139) |
26.4% (1,131) | 26.8% (1,149) |
28.2% (1,205) |
27.0% (4,624) |
| College graduate and above | 43.2% (1,848) |
34.7% (1,486) | 35.4% (1,517) |
36.4% (1,559) |
37.4% (6,410) |
| Income | |||||
| < $20,000 | 14.7% (629) | 18.4% (787) | 16.9% (723) |
16.0% (684) | 16.5% (2,823) |
| $20,000–$34,000 | 22.2% (949) | 23.4% (1,002) | 23.3% (999) |
25.0% (1,071) |
23.5% (4,021) |
| $35,000–$74,000 | 32.5% (1,390) |
30.2% (1,293) | 30.7% (1,313) |
31.5% (1,347) |
31.2% (5,343) |
| >=$75,000 | 19.6% (841) | 16.0% (683) | 17.7% (756) |
16.8% (719) | 17.5% (2,999) |
| Refused | 11.0% (473) | 12.1% (517) | 11.5% (492) |
10.7% (458) | 11.3% (1,940) |
| Region | |||||
| Rest of US | 68.4% (2,928) |
28.0% (1,198) | 42.7% (1,830) |
44.3% (1,895) |
45.8% (7,851) |
| Stroke Belt | 20.8% (892) | 35.7% (1,527) | 35.2% (1,507) |
46.5% (1,989) |
34.5% (5,915) |
| Stroke Buckle | 10.8% (462) | 36.4% (1,557) | 22.1% (946) |
9.2% (395) | 19.6% (3,360) |
| Urbanicity | |||||
| Rural(<=25% urban) | 8.6% (367) | 12.8% (548) | 10.5% (449) |
6.8% (291) | 9.7% (1,655) |
| Mixed(25–75% urban) | 8.7% (371) | 14.2% (609) | 10.3% (443) |
7.8% (333) | 10.3% (1,756) |
| Urban(>=75% urban) | 82.8% (3,544) |
73.0% (3,125) | 79.2% (3,391) |
85.4% (3,655) |
80.1% (13,715) |
| Physical activity | |||||
| None | 31.2% (1,338) |
32.5% (1,393) | 33.8% (1,447) |
33.9% (1,450) |
32.9% (5,628) |
| 1 to 3 time per week | 37.1% (1,590) |
37.0% (1,583) | 38.5% (1,647) |
38.1% (1,630) |
37.7% (6,450) |
| 4 or more per week | 31.6% (1,354) |
30.5% (1,306) | 27.8% (1,189) |
28.0% (1,199) |
29.5% (5,048) |
| Alcohol use | |||||
| None | 55.5% (2,377) |
63.4% (2,713) | 63.4% (2,716) |
63.5% (2,719) |
61.5% (10,525) |
| Moderate | 39.6% (1,694) |
32.2% (1,378) | 32.8% (1,405) |
33.0% (1,410) |
34.4% (5,887) |
| Heavy | 4.9% (211) | 4.5% (191) | 3.8% (162) |
3.5% (150) | 4.2% (714) |
| Packyears | 0.2 (0.0, 18.0) | 0.1 (0.0,16.0) | 0.1 (0.0,16.5) |
0.07 (0.0,15.0) |
0.1 (0.0,16.5) |
| Antihypertensive | 47.3% (2,025) |
50.4% (2,157) | 52.3% (2,240) |
51.8% (2,216) |
50.4% (8,638) |
| Statin use | 26.4% (1,131) |
27.0% (1,154) | 26.1% (1,119) |
26.3% (1,126) |
26.5% (4,530) |
| Diabetes | 15.7% (673) | 19.2% (822) | 20.2% (864) |
18.3% (782) | 18.3% (3,141) |
|
Body mass index (kg/m2) |
28.1 (25.0,32.1) |
28.3 (25.0,32.6) |
28.3 (25.0,32.7) |
28.2 (25.1,32.4) |
28.3 (25.0,32.4) |
| Temperature (Celsius) | 18.3 (14.0,21.5) |
18.6 (16.7,20.7) |
16.6 (13.1,18.8) |
17.3 (13.9,18.4) |
17.6 (14.2,19.7) |
| Season | |||||
| Fall | 19.9% (854) | 23.3% (999) | 21.0% (898) |
27.5% (1,175) |
22.9% (3,926) |
| Spring | 25.7% (25.0,32.4)(1,099) |
23.6% (1,011) | 25.9% (25.0,32.4)(1,109) |
19.9% (853) | 23.8% (25.0,32.4)(4,072) |
| Summer | 33.5% (25.0,32.4)(1,434) |
29.9% (1,281) | 29.6% (1,268) |
26.9% (1,150) |
30.0% (5,133) |
| Winter | 20.9% (895) | 23.1% (991) | 23.5% (1,008) |
25.7% (1,101) |
23.3% (3,995) |
| Year of baseline visit | |||||
| 2003 | 18.1% (773) | 16.5% (706) | 11.1% (25.0,32.4)(477) |
19.9% (851) | 16.4% (25.0,32.4)(2,807) |
| 2004 | 31.7% (25.0,32.4)(1,359) |
27.9% (1,195) | 37.3% (1,596) |
26.0% (1,112) |
30.7% (5,262) |
| 2005 | 17.6% (752) | 24.1% (1,032) | 22.4% (960) |
27.2% (1,164) |
22.8% (3,908) |
| 2006 | 10.4% (444) | 16.8% (721) | 19.6% (25.0,32.4)(840) |
19.5% (835) | 16.6% (25.0,32.4)(2,840) |
| 2007 | 22.3% (954) | 14.7% (628) | 9.6% (25.0,32.4)(410) |
7.4% (317) | 13.5% (2,309) |
a (b, c) represent the median a, the lower quartile b, and the upper quartile c for continuous variables. Numbers after proportions are frequencies.