Table 1 Distribution of daily ambient air pollutants, PM 2.5 chemical constituents and weather variables by study period
| Â | Medians for different study periods | Percentiles over the entire study | IQR | ||||||
|---|---|---|---|---|---|---|---|---|---|
Suburban Period (n=59) | Urban Period 1 (n=66) | Urban Period 2 (n=63) | 5th | 25th | 50th | 75th | 95th | ||
Particles | Â | Â | Â | Â | Â | Â | Â | Â | Â |
 PM10, μg/m3 | 134.0 | 96.0 | 111.0 | 28.6 | 76.3 | 112.0 | 149.8 | 275.0 | 73.5 |
 PM2.5–10, μg/m3 | 52.8 | 35.9 | 56.6 | 2.4 | 21.1 | 45.6 | 71.4 | 141.9 | 50.3 |
 PM2.5, μg/m3 | 75.2 | 56.6 | 48.8 | 13.2 | 32.7 | 57.4 | 96.1 | 177.8 | 63.4 |
Gaseous air pollutants | |||||||||
 CO, ppm | 0.89 | 1.71 | 1.39 | 0.55 | 0.95 | 1.34 | 1.72 | 2.47 | 0.77 |
 NOX, ppb | 39.7 | 58.3 | 50.4 | 20.5 | 35.6 | 47.6 | 65.4 | 123.2 | 29.9 |
 NO2, ppb | 23.4 | 36.2 | 31.7 | 12.5 | 23.1 | 30.2 | 38.8 | 58.3 | 15.7 |
 NO, ppb | 15.2 | 24.4 | 17.2 | 1.0 | 8.5 | 18.1 | 26.6 | 73.0 | 18.2 |
Carbonaceous fractions | |||||||||
 OC, μg/m3 | 9.2 | 11.1 | 10.0 | 4.0 | 7.1 | 10.1 | 13.0 | 20.6 | 5.6 |
 EC, μg/m3 | 1.81 | 2.83 | 1.58 | 0.4 | 1.2 | 1.9 | 3.0 | 5.6 | 1.75 |
 POC, μg/m3 | 4.1 | 6.9 | 5.7 | 1.1 | 3.3 | 5.3 | 7.9 | 14.3 | 4.6 |
 SOC, μg/m3 | 4.7 | 3.7 | 4.4 | 1.2 | 3.0 | 4.4 | 5.8 | 9.9 | 2.7 |
 POM, μg/m3 | 15.1 | 17.8 | 16.1 | 6.4 | 11.8 | 16.2 | 20.9 | 32.9 | 9.0 |
Ions | |||||||||
 SO4 2-, μg/m3 | 10.6 | 5.0 | 4.2 | 0.9 | 2.8 | 6.6 | 18.1 | 41.3 | 15.3 |
 NO3 -, μg/m3 | 2.1 | 2.0 | 0.7 | 0.04 | 0.4 | 1.6 | 3.6 | 9.9 | 3.19 |
 Cl-, μg/m3 | 0.8 | 0.8 | 0.5 | 0.04 | 0.2 | 0.7 | 1.5 | 5.2 | 1.25 |
 F-, ng/m3 | 15.1 | 46.0 | 37.4 | 6.9 | 14.7 | 36.4 | 67.5 | 143.0 | 52.8 |
Crustal metals | |||||||||
 Al, μg/m3 | 0.67 | 0.48 | 0.35 | 0.09 | 0.31 | 0.51 | 0.79 | 2.47 | 0.49 |
 Ca, μg/m3 | 0.83 | 0.71 | 0.82 | 0.18 | 0.54 | 0.80 | 1.22 | 2.34 | 0.68 |
 Na, μg/m3 | 0.45 | 0.61 | 0.57 | 0.14 | 0.35 | 0.53 | 0.77 | 1.58 | 0.42 |
 K, μg/m3 | 1.01 | 1.33 | 0.85 | 0.08 | 0.53 | 1.12 | 1.58 | 3.16 | 1.05 |
 Mg, ng/m3 | 209.9 | 190.7 | 210.6 | 51.5 | 154.7 | 199.2 | 303.5 | 690.4 | 147.8 |
 Sr, ng/m3 | 7.8 | 6.2 | 5.6 | 1.4 | 4.0 | 6.4 | 9.0 | 16.7 | 4.9 |
 Ba, ng/m3 | 12.6 | 18.3 | 12.0 | 3.2 | 7.4 | 13.9 | 20.7 | 30.7 | 13.3 |
Transition metals | |||||||||
 Fe, μg/m3 | 0.74 | 0.72 | 0.55 | 0.09 | 0.41 | 0.69 | 0.91 | 1.68 | 0.51 |
 Zn, μg/m3 | 0.29 | 0.27 | 0.33 | 0.05 | 0.13 | 0.29 | 0.59 | 1.05 | 0.46 |
 Cu, ng/m3 | 23.1 | 27.9 | 20.2 | 2.1 | 10.6 | 23.9 | 40.8 | 87.7 | 30.2 |
 Ti, ng/m3 | 40.9 | 37.8 | 30.4 | 6.8 | 23.5 | 37.2 | 49.9 | 110.8 | 26.4 |
 Co, ng/m3 | 0.38 | 0.36 | 0.35 | 0.02 | 0.25 | 0.37 | 0.52 | 2.41 | 0.28 |
 Ni, ng/m3 | 3.1 | 2.7 | 2.3 | 0.8 | 1.8 | 2.8 | 4.3 | 8.5 | 2.5 |
 Mo, ng/m3 | 1.3 | 1.2 | 0.7 | 0.2 | 0.6 | 1.0 | 1.5 | 3.1 | 0.9 |
 Cd, ng/m3 | 1.9 | 2.2 | 1.6 | 0.1 | 0.8 | 2.0 | 3.7 | 9.1 | 2.9 |
 V, ng/m3 | 2.7 | 1.2 | 1.5 | 0.3 | 0.9 | 1.6 | 2.7 | 5.6 | 1.8 |
 Cr, ng/m3 | 8.7 | 7.4 | 7.1 | 2.6 | 5.4 | 7.8 | 11.5 | 32.7 | 6.1 |
 Mn, ng/m3 | 60.6 | 59.2 | 44.2 | 12.5 | 35.8 | 51.9 | 73.4 | 117.5 | 37.6 |
Other metals/metalloid elements | |||||||||
 As, ng/m3 | 7.6 | 8.0 | 21.8 | 1.2 | 4.4 | 10.5 | 25.5 | 96.7 | 21.1 |
 Se, ng/m3 | 6.2 | 4.0 | 2.6 | 0.5 | 2.3 | 4.2 | 7.4 | 13.3 | 5.1 |
 Sn, ng/m3 | 5.6 | 5.7 | 5.6 | 0.6 | 2.5 | 5.6 | 10.8 | 22.9 | 8.3 |
 Sb, ng/m3 | 4.8 | 7.0 | 4.9 | 0.4 | 2.2 | 5.5 | 9.7 | 19.2 | 7.5 |
 Pb, ng/m3 | 104.0 | 91.1 | 84.9 | 7.7 | 38.5 | 94.2 | 181.6 | 383.9 | 143.1 |
Temperature, °C | 25.0 | 17.6 | 22.7 | 12.3 | 17.2 | 21.6 | 26.1 | 29.9 | 8.9 |
Relative humidity, % | 47.4 | 53.6 | 34.4 | 26.6 | 33.6 | 46.2 | 58.0 | 77.2 | 24.4 |