Characteristics of study subjects
| NO, nitric oxide. | |
| No subjects required treatment with inhaled corticosteroids before the pollen season. | |
| Mean (range) age (years) | 11.2 (7–16) |
| Male:female | 35:9 |
| Mean (range) duration of asthma (years) | 4.2 (1–12) |
| Mean (range) duration of rhinoconjunctivitis (years) | 4.2 (1–12) |
| Sensitisation | |
| Phleum pratense | 44 (100%) |
| Tree pollens | 11 (25%) |
| House dust mite | 14 (32%) |
| Mean (range) dose of inhaled steroids during previous summer (μg beclomethasone equivalent) | 325 (0–800) |
| No (%) requiring long acting antihistamine | 41 (93%) |
| No (%) requiring long active topical nasal steroids | 21 (48%) |
| Median (range) number of pre-season exhaled NO readings | 5.0 (1–9) |
| Median (range) number of pollen season exhaled NO readings | 2 (1–3) |