Characteristics of study population measured in summer 1998 (n=235)
| Mean (SD) age (years) | 10.8 (1.1) |
| No (%) with wheeze in the last 4 weeks | 77/230 (33.5%) |
| No (%) with dry cough only in the 4 weeks | 31/228 (13.5%) |
| No (%) with AHR | 98/235 (41.7%) |
| No (%) taking inhaled corticosteroids | 27/235 (11.5%) |
| Median (range) no of breaths collected | 2 (1–7) |
| Median (range) flow rate (l/min) | 9 (2–18) |
| Mean (95% CI) ambient NO (ppb) | 5.8 (5.5 to 6.0) |