Table 1

Characteristics of the studies included in the meta-analysis

AuthorYearPopulationNumber of personsAgeMen, %Study design (measurements per person)ExposureScale of HRVLength of analysed ECG recordingsAverage PM concentration, μg/m3
Liao121999All‖489962.4±5.7B43Cross-sectional24 h PM2.5HF and LF Log5 min16.99±8.04B*
Without hypertension878 (65–84)A37
With hypertension1882 (69–89)A22
Pope131999With CVD/respiratory disease775 (23–82)C85.7Longitudinal (4.1)24 h PM10Lin24 h83.92D*
Gold142000Elderly2173.3 (53–87)C48Longitudinal (7.76)4 h PM2.5Lin5 min15.3 (2.9–48.6)A
Brauer152001With COPD1674 (54–86)A43.8Longitudinal (7)24 h PM2.5Lin24 h10.8±1.4E
Magari162001Occupational3338.1±12.9B100Longitudinal (2)4 h PM2.5Log24 h223±2203E
Holguin172003Without hypertension2180 (65–96)A52Longitudinal (18)24 h PM2.5Log5 min30.4±9.9B
With hypertension1378 (60–88)A30
Liao182004All Without hypertension489962.4±5.7B43Cross-sectional24 h PM10HF and LF Log5 min16.99±8.04B*
With hypertension
Pope192004Elderly8854–89F43Longitudinal (2.84)24 h PM2.5Log24 h23.7±20.2B
Riediker202004Occupational, young927.3 (23–30)A100Longitudinal (4)9 h PM2.5Lin10 min23 (7.1–38.7)A
Park212005Elderly (NAS)49772.7±6.6B100Cross-sectional48 h PM2.5Log4 min11.4±8.08B
Schwartz222005Elderly2774 (64–81)GPredominately femaleLongitudinal (12)24 h PM2.5Log30 min10 (7–17)G
Sullivan232005With CVD2177 (57–85)C43Longitudinal (8.38)24 h PM2.5Ln20 min10.7 (8.0–15.6)G
Without CVD1378 (72–87)C46
Lipsett62006With CAD1971.3±6.0B63.2Longitudinal (12)6 h PM10Log24 h
Luttmann-Gibson242006General3270.8 (54–90)A9Longitudinal (21.8)24 h PM2.5Log30 min19.7 (11.6–25.0)H
Timonen252006With CAD, Amsterdam3771.5±8.3B65Longitudinal (10.92)72 h PM2.5HF Ln25 min20.0 (10.4–23.9)H
With CAD, Ertfurt4764.6±8B91SDNN, rMSSD23.1 (10.5–27.4)H
With CAD, Helsinki4768.3±6.4B55Log12.7 (8.1–16.0)H
Vallejo262006Young4027 (21–35)A27.5Longitudinal (33)3.5 h PM2.5Ln13 h74 (49–111)G
Riojas-Rodriuguez 272006General3055 (25–76)A83Longitudinal (111)11 h PM2.5Ln11 h46.8±1.82E
Chuang282007Young7620.8±1.2B66.7Longitudinal (3)24 h PM2.5Log16 min31.8±10.6B
Chuang292007Elderly4670.0±11.7B41Longitudinal (168)4 h PM2.5Log24 h51.7±40.1B
Min302008General134944.3±21.9B43.63Cross-sectional24 h PM10Log5 min23.25±13.3B*
Folino312009With MI3960.3±4.8B92.3Longitudinal (2.7)24 h PM2.5Lin24 h33.9±12.7B
Whitsel322009All547064±0.1B0Longitudinal (3)24 h PM10Log10 s19.6±0.14B*
Impaired fasting glucose1559
Normal fasting glucose3141
Zanobetti332009With CAD4657 (43–75)C80.4Longitudinal (4)2 h PM2.5Log24 h8.92 (5.65–13.58)G
Park342010General546562.2±10.9B46.8Cross-sectional24 h PM2.5Log30 s14.3 (10.2–20.4)G
Schneider352010With CAD5666±6B100Longitudinal (12)24 h PM2.5Log24 h20.3±14.8B
Suh362010All3065 (55–73)HLongitudinal (7)24 h PM2.5Log25 min
With COPD1838.916.54±9.33B
With MI1283.314.65±7.7B
Wu372010Occupational1135.5 (27–41)A45Longitudinal (3)2 h PM2.5Log12 h56.6 (34.6–104.1)G
He382011General10656.23±7.61B40.57Longitudinal (48)6 h PM2.5HF,LF Log24 h13.21±14.44B
Jia392011General3057.9±5.4B40Longitudinal (116)24 h PM2.5Log24 h37.52(0.19–214.5)I
  • Descriptive statistics were only given for all participants. No calculations could be made for rMSSD.

  • Population: description of persons included.

  • Age, Average PM concentration: A, arithmetic mean (range); B, arithmetic mean ± SD; C, median (range); D, mean; E, geometric mean ± SD; F, range; G, median (25%–75% percentile); H, arithmetic mean (25%–75% percentile); I, median (1%–99% percentile).

  • * Average PM2.5 concentration calculated with the assumption that PM10 consists of 70% of PM2.5.

  • Average age/PM2.5 concentration during the first visit.

  • Mass, after shift.

  • CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; MI, myocardial infarction; NAS, Normative Aging Study; PM2.5, particulate matter with aerodynamic diameter of 2.5 μm or less; PM10, particulate matter with aerodynamic diameter of 10 μm or less. ‖Descriptive statistics were only given for all participants. No calculations could be made for rMSSD.