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Table 1 Characteristics of the study population in the Normative Aging Study (2000 to 2016)

From: Metabolomic signatures of the long-term exposure to air pollution and temperature

Demographic Characteristics At first visit (2000 to 2013) (N = 456) All visits (2000 to 2016) (N = 648)
Age, Mean (SD) 75.0 (6.70) 76.0 (6.68)
Body mass index (kg/m2), Mean (SD) 27.7 (4.19) 27.7 (4.27)
Years of education, Mean (SD) 15.1 (3.00) 15.0 (3.00)
Baseline annual income, thousands of 1965 $US, Mean (SD) 8.61 (3.77) 8.64 (3.78)
Smoking
 Never, N (%) 128 (28) 190 (29)
 Current, N (%) 14 (3) 21 (3)
 Former, N (%) 314 (69) 437 (67)
Pack-year smoked (years), Mean (SD) 21.4 (25.2) 20.95 (25.36)
Season
 Cold: October–March, N (%) 189 (41) 259 (40)
 Warm: April–September, N (%) 267 (59) 389 (60)
Alcohol consumption (≥2 drinks per day), N (%) 95 (21) 132 (20)
Mean (SD), (IQR) of the exposure levels
 Average of 365 days of PM2.5 (μg/m3) 10.4 (1.28), (2.49) 10.1 (1.31), (2.12)
 Average of 365 days of NO2 (ppb) 19.1 (2.40), (4.52) 18.4 (2.35), (4.00)
 Average of 365 days of O3 (ppb) 23.7 (1.06), (1.39) 24.0 (1.12), (1.45)
 Average of 365 days of Temperature (°C) 11.0 (0.64), (1.00) 11.0 (0.60), (0.89)
  1. Abbreviations: N Number of participants or visits, SD Standard deviation, ppb is part per billion, Kg Kilogram, m Meters, C Celsius, IQR Interquartile range