Table 3.
Average daily levels of ambient air pollutants, overall and stratified by season.a
| Pollutant | Unit | All year | Warm season | Cool season | |||
|---|---|---|---|---|---|---|---|
| Mean ± SD | Median | Mean ± SD | Median | Mean ± SD | Median | ||
| PM2.5 | μg/m3 | 8.6 ± 4.9 | 7.3 | 9.1 ± 5.6 | 7.4 | 8.2 ± 4.2 | 7.1 |
| SO42– | μg/m3 | 2.6 ± 2.1 | 2.0 | 2.9 ± 2.6 | 2.0 | 2.3 ± 1.4 | 2.0 |
| BC | μg/m3 | 0.62 ± 0.35 | 0.55 | 0.66 ± 0.33 | 0.62 | 0.60 ± 0.36 | 0.52 |
| UFP | 1,000/m3 | 15.3 ± 6.7 | 14.5 | 11.7 ± 4.5 | 10.6 | 18.2 ± 6.8 | 17.1 |
| O3 | ppb | 24.5 ± 10.8 | 23.4 | 30.0 ± 10.7 | 29.1 | 19.4 ± 8.1 | 18.8 |
| CO | ppm | 0.31 ± 0.14 | 0.30 | 0.30 ± 0.12 | 0.29 | 0.32 ± 0.16 | 0.30 |
| NO | ppb | 13.2 ± 10.0 | 10.2 | 9.2 ± 4.4 | 8.3 | 16.8 ± 12.2 | 13.2 |
| NO2 | ppb | 16.7 ± 5.6 | 15.9 | 14.7 ± 4.2 | 14.4 | 18.6 ± 6.1 | 18.1 |
| aWarm season: April–September, cool season: October–March. | |||||||