Odds ratios (OR) and percentages for symptoms of asthma and rhinitis among children attending arenas using propane-powered resurfacing machines with high (mean 510 µg·m−3) concentrations of nitrogen dioxide (NO2) in relation to children from such arenas with low (mean 89 µg·m−3) concentrations
| High NO2 | Low NO2 | OR# (95% confidence interval) | |
| Asthma | |||
| Wheezing ever | 90 (21.4) | 87 (16.2) | 1.4 (1.0–1.9) |
| Wheezing 12 months | 61 (14.5) | 63 (11.7) | 1.2 (0.8–1.8) |
| Exercise wheeze | 49 (11.7) | 51 (9.5) | 1.2 (0.8–1.9) |
| Asthma ever | 71 (16.9) | 69 (12.9) | 1.4 (0.9–2.0) |
| Asthma diagnosed by physician | 66 (15.7) | 63 (11.7) | 1.4 (0.9–2.0) |
| Asthma medication 12 months | 68 (16.2) | 76 (14.2) | 1.2 (0.8–1.7) |
| Rhinitis¶ | |||
| Nose symptoms ever | 130 (30.9) | 114 (21.3) | 1.7 (1.3–2.3) |
| Nose symptoms 12 months | 114 (27.2) | 97 (18.1) | 1.7 (1.2–2.4) |
Data are presented as n (%) unless otherwise stated
#: odds ratios adjusted for parental history of allergic disease and sex
¶: nose symptoms without upper respiratory infection