24 Hour means (SDs) for air pollutants (μg/m3 except PM10 - ppb) and daily incidence of wheezy cases and controls
| Spring | Summer | Autumn | Winter | All seasons | |
| Pollutant | |||||
| Ozone | 46.3 (16.7)*** | 40.6 (13.3)*** | 22.0 (15.4) | 22.3 (15.9) | 32.7 (18.8) |
| SO2 | 13.6 (11.5)*** | 14.7 (14.3)*** | 14.7 (13.4) | 27.7 (24.3) | 17.7 (17.5) |
| NO2 | 41.7 (19.1)2-150 | 37.8 (14.4)*** | 46.0 (17.6)*** | 48.7 (17.4) | 43.6 (17.6) |
| PM10 | 23.5 (11.6)*** | 23.8 (10.8)*** | 19.7 (10.7)*** | 32.2 (20.1) | 24.9 (14.6) |
| Benzene | 2.54 (1.24)2-160 | 2.59 (1.33) | 5.08 (4.22) | 4.08 (2.56) | 3.57 (2.83) |
| 1,3-Butadiene | 0.86 (0.55)2-160 | 1.02 (0.74) | 1.82 (2.01) | 1.33 (1.34) | 1.26 (1.34) |
| cis-2-Butene | 0.19 (0.09) | 0.22 (0.10) | 0.47 (0.46)2-160 | 0.31 (0.30) | 0.30 (0.30) |
| n-Butane | 6.12 (3.71) | 6.39 (3.57) | 13.00 (11.65)2-160 | 9.14 (7.53) | 8.65 (7.85) |
| tr-2-Butene | 0.40 (0.13) | 0.43 (0.16) | 0.77 (0.64)2-160 | 0.54 (0.42) | 0.53 (0.42) |
| Ethene | 5.27 (2.66)*** | 5.49 (2.82)*** | 11.68 (10.00) | 10.80 (7.58) | 8.29 (7.16) |
| Ethylbenzene | 1.36 (0.67)2-150 | 1.44 (0.76) | 3.18 (2.85)2-160 | 2.17 (1.63) | 2.06 (1.89) |
| Ethyne | 3.48 (1.92)2-160 | 3.18 (1.66)*** | 7.08 (6.24) | 5.63 (2.68) | 4.82 (3.94) |
| n-Heptane | 0.30 (0.15)*** | 0.30 (0.15)*** | 0.63 (0.55) | 0.52 (0.37) | 0.44 (0.37) |
| n-Hexane | 0.69 (0.47)2-160 | 0.76 (0.44)2-160 | 1.23 (1.04) | 1.11 (0.85) | 0.94 (0.77) |
| m+p-Xylene | 3.36 (1.74)2-150 | 3.62 (2.02) | 8.07 (7.31)*** | 5.29 (4.22) | 5.14 (4.86) |
| o-Xylene | 1.38 (0.74)2-150 | 1.31 (0.64)2-150 | 3.20 (2.99)2-160 | 2.23 (1.71) | 2.06 (1.95) |
| cis-2-Pentene | 0.14 (0.07) | 0.17 (0.99) | 0.38 (0.20)*** | 0.22 (0.20) | 0.22 (0.23) |
| iso-Pentane | 6.59 (3.94) | 7.67 (4.27) | 11.93 (10.86)*** | 7.56 (7.30) | 8.44 (7.41) |
| trans-2-Pentene | 0.23 (0.13) | 0.32 (0.19) | 0.69 (0.66)*** | 0.40 (0.38) | 0.41 (0.43) |
| me-Pentane | 2.70 (1.47)2-150 | 2.93 (1.58) | 5.47 (5.17)2-150 | 4.12 (3.56) | 3.80 (3.48) |
| n-Pentane | 1.32 (0.77)2-150 | 1.58 (0.91) | 2.61 (2.19)2-160 | 1.79 (1.35) | 1.82 (1.49) |
| Toluene | 6.37 (3.27)2-150 | 6.92 (3.57) | 14.00 (12.63)2-160 | 9.76 (7.99) | 9.26 (8.39) |
| Ethane | 5.15 (2.24)*** | 3.83 (1.76)*** | 6.69 (5.14) | 7.88 (3.54) | 5.88 (3.74) |
| Propane | 2.36 (1.31)*** | 1.95 (0.99)*** | 4.02 (3.13) | 4.58 (2.27) | 3.22 (2.36) |
| Isoprene | 0.26 (0.20) | 0.60 (0.31)*** | 0.48 (0.41)2-160 | 0.30 (0.26) | 0.41 (0.33) |
| Average HC | 2.45 (1.19)2-150 | 2.40 (1.13)2-150 | 5.05 (4.25)2-150 | 3.75 (2.60) | 3.47 (2.86) |
| Incidence: | |||||
| All cases | 3.2 (1.9)2-160 | 3.2 (2.8)2-160 | 5.1 (2.7) | 4.5 (2.5) | 4.0 (2.6) |
| Cases <2 years | 2.0 (1.0)*** | 0.8 (1.1)*** | 2.3 (1.8) | 2.0 (1.7) | 1.6 (1.6) |
| Cases >2 years | 2.1 (1.5) | 2.3 (2.2) | 2.8 (1.8) | 2.5 (1.9) | 2.4 (1.9) |
| All controls | 63.5 (9.8)*** | 59.5 (10.1) | 56.8 (9.9) | 56.5 (9.2) | 59.1 (10.1) |