Association of climatic factors with the 12 month period prevalence rates (in %) of symptoms of asthma, assessed by video questionnaire (VQ), in children; results of the multilevel linear regression analyses
| Worldwide* | Western Europe | |||
|---|---|---|---|---|
| 13–14 years RC† (95% CI) | 6–7 years RC† (95% CI) | 13–14 years RC† (95% CI) | 6–7 years RC† (95% CI) | |
| *Adjusted for GNP. | ||||
| †Regression coefficient with 95% confidence interval. | ||||
| ‡All centres had ⩾1 month with mean relative humidity indoors below 50%. | ||||
| Latitude (degrees) | −0.05 (−0.11 to 0.02) | – | −0.02 (−0.12 to 0.07) | – |
| Altitude (100 m) | 0.06 (−0.15 to 0.26) | – | −0.20 (−0.43 to 0.04) | – |
| Outdoor temperature | ||||
| Mean annual temperature (°C) | 0.04 (−0.07 to 0.15) | – | 0.09 (−0.06 to 0.24) | – |
| Annual variation in mean temperature (°C) | −0.05 (−0.74 to 0.64) | – | −1.22 (−2.49 to 0.06) | – |
| Lowest monthly mean temperature (°C) | 0.00 (−0.06 to 0.06) | – | 0.07 (−0.03 to 0.18) | – |
| Mean temperature of ⩾1 month below 0°C | −0.85 (−2.41 to 0.71) | – | −1.42 (−2.87 to 0.02) | – |
| Outdoor relative humidity | ||||
| Mean annual relative humidity (%) | −0.06 (−0.12 to 0.00) | – | 0.05 (−0.05 to 0.15) | – |
| Annual variation in mean relative humidity (%) | 0.25 (−0.37 to 0.88) | – | −0.63 (−1.22 to −0.03) | – |
| Lowest monthly mean relative humidity (%) | −0.03 (−0.07 to 0.01) | – | 0.04 (0.00 to 0.09) | – |
| Mean relative humidity of ⩾1 month below 50% | 1.43 (0.01 to 2.86) | – | −1.22 (−2.86 to 0.42) | – |
| Indoor relative humidity at 20°C | ||||
| Mean annual relative humidity (%) | −0.01 (−0.04 to 0.02) | – | 0.07 (0.01 to 0.14) | – |
| Annual variation in mean relative humidity (%) | 0.06 (−0.24 to 0.36) | – | 0.15 (−0.32 to 0.62) | – |
| Lowest monthly mean relative humidity (%) | 0.00 (−0.03 to 0.04) | – | 0.07 (0.00 to 0.13) | – |
| Mean relative humidity of ⩾1 month below 50% | 0.38 (−1.03 to 1.79) | – | ‡ | – |