Table 2.
Summary Statistics and Pearson Correlation Coefficients of 24-Hour Mean Air Pollutant Concentrations and Meteorological Variables in the Veterans Affairs Normative Aging Study, Boston, Massachusetts, July 2007–August 2011
| Exposure | Summary Statistics |
r |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No. | Mean (SD) | Median (IQR) | PM2.5 | Black Carbon | PNC | NO2 | O3 | SO42− | Temperature | Relative Humidity | |
| PM2.5, μg/m3 | 1,508 | 8.6 (4.7) | 7.3 (5.7, 10.2) | 1.00 | 0.65 | −0.06 | 0.37 | 0.24 | 0.79 | 0.29 | 0.16 |
| Black carbon, μg/m3 | 1,503 | 0.7 (0.3) | 0.6 (0.5, 0.8) | 1.00 | 0.20 | 0.65 | −0.20 | 0.48 | 0.13 | 0.28 | |
| PNC, counts/cm3 | 1,424 | 13,160 (5,577) | 13,233.4 (8,568, 16,401) | 1.00 | 0.48 | −0.45 | −0.26 | −0.66 | −0.18 | ||
| Nitrogen dioxide, ppm | 1,512 | 0.02 (0.01) | 0.02 (0.01, 0.02) | 1.00 | −0.37 | 0.23 | −0.36 | −0.04 | |||
| Ozone, ppm | 1,512 | 0.03 (0.01) | 0.03 (0.02, 0.03) | 1.00 | 0.34 | 0.42 | −0.19 | ||||
| Sulfate, μg/m3 | 1,100 | 2.3 (1.9) | 1.7 (1.0, 2.6) | 1.00 | 0.32 | 0.17 | |||||
| Temperature, °C | 1,511 | 13.3 (8.9) | 14.0 (6.0, 20.6) | 1.00 | 0.14 | ||||||
| Relative humidity, % | 1,511 | 66.8 (15.0) | 65.9 (55.3, 78.5) | 1.00 | |||||||
Abbreviations: IQR, interquartile range; PM2.5, particles with aerodynamic diameter <2.5 μm; PNC, particle number count; SD, standard deviation.