Table 2. The relative risks (RRs) for pediatric outpatient visits for asthma during cold spells compared with non-cold spell days in cold seasons, 2007–2009a.
| Lags | RR (95% CI) | |||
| Model 1b | Model 2c | Model 3d | Model 4e | |
| Lag 0 | 1.25 (1.08, 1.44)** | 1.25 (1.08, 1.45)** | 1.06 (0.93, 1.20) | 1.05 (0.92, 1.20) |
| Lag 1–2 | 1.29 (1.13, 1.47)** | 1.30 (1.13, 1.48)** | 1.11 (0.98, 1.25) | 1.09 (0.96, 1.23) |
| Lag 3–6 | 1.29 (1.14, 1.46)** | 1.29 (1.14, 1.47)** | 1.09 (0.97, 1.22) | 1.07 (0.95, 1.20) |
| Lag 7–14 | 1.26 (1.12, 1.42)** | 1.26 (1.13, 1.42)** | 1.12 (1.02, 1.25)* | 1.12 (1.02,1.25)* |
| Lag 15–30 | 1.06 (0.95, 1.19)** | 1.06 (0.95, 1.19)** | 1.02 (0.92, 1.13) | 1.03 (0.93, 1.14) |
| Lag 1–30 | 1.26 (1.14, 1.38)** | 1.25 (1.14, 1.39)** | 1.08 (0.98, 1.18) | 1.06 (0.97, 1.17) |
a
All the models were adjust for day of the week, season and long-term trend;
b
Model 1 did not controlled for relative humidity and O3;
c
Model 2 controlled for relative humidity;
d
Model 3 controlled for O3;
e
Model 4 controlled for relative humidity and O3;
*
<0.05;
**
P<0.01.