Association* between air pollution (per IQR increase in mean 5-day (lag0-4) levels) and hospital admission for asthma in children, and effect modification by gender and age
| Pollutants | Subgroup | n | OR (95% CI) | p Value† | |
| NOx | Overall | 8155 | 1.11 (1.05 to 1.17) | ||
| Gender | Boys | 5508 | 1.13 (1.06 to 1.20) | 0.34 | |
| Girls | 2647 | 1.08 (1.00 to 1.17) | |||
| Age | Infants (0–1 years) | 2741 | 1.12 (1.04 to 1.21) | 0.97 | |
| Preschool children (2–5 years) | 2873 | 1.11 (1.02 to 1.20) | |||
| School children (6–18 years) | 2541 | 1.10 (1.02 to 1.20) | |||
| NO2 | Overall | 8155 | 1.10 (1.04 to 1.16) | ||
| Gender | Boys | 5508 | 1.11 (1.05 to 1.18) | 0.44 | |
| Girls | 2647 | 1.08 (0.99 to 1.17) | |||
| Age | Infants (0–1 years) | 2741 | 1.10 (1.02 to 1.19) | 1.00 | |
| Preschool children (2–5 years) | 2873 | 1.10 (1.02 to 1.19) | |||
| School children (6–18 years) | 2541 | 1.10 (1.02 to 1.20) | |||
| PM10 | Overall | 8155 | 1.07 (1.03 to 1.12) | ||
| Gender | Boys | 5508 | 1.07 (1.02 to 1.12) | 0.93 | |
| Girls | 2647 | 1.07 (1.00 to 1.14) | |||
| Age | Infants (0–1 years) | 2741 | 1.11 (1.05 to 1.18) | 0.20 | |
| Preschool children (2–5 years) | 2873 | 1.03 (0.97 to 1.10) | |||
| School children (6–18 years) | 2541 | 1.07 (1.00 to 1.14) | |||
| PM2.5 | Overall | Overall | 6329 | 1.09 (1.04 to 1.13) | |
| Gender | Boys | 4338 | 1.10 (1.05 to 1.15) | 0.33 | |
| Girls | 1991 | 1.06 (0.99 to 1.13) | |||
| Age | Infants (0–1 years) | 2161 | 1.11 (1.04 to 1.18) | 0.62 | |
| Preschool children (2–5 years) | 2236 | 1.06 (1.00 to 1.13) | |||
| School children (6–18 years) | 1932 | 1.09 (1.01 to 1.16) | |||
| UFPs | Overall | Overall | 7004 | 1.06 (0.98 to 1.14) | |
| Gender | Boys | 4756 | 1.06 (0.97 to 1.15) | 0.93 | |
| Girls | 2248 | 1.06 (0.95 to 1.20) | |||
| Age | Infants (0–1 years) | 2369 | 1.08 (0.97 to 1.22) | 0.71 | |
| Preschool children (2–5 years) | 2464 | 1.07 (0.96 to 1.20) | |||
| School children (6–18 years) | 2171 | 1.02 (0.91 to 1.15) |