| Risk factors | Total participants# | Missing data¶ | Imputed |
| Subjects n | 1570 | ||
| Subjects in SOLAR II aged ≤21 years+ | 552 (35.2) | 0 | No |
| Female | 918 (58.5) | 0 | No |
| Study location Munich | 758 (48.3) | 0 | No |
| Nationality German | 1518 (96.7) | 5 (0.3) | Yes |
| High socioeconomic status§ | 921 (58.7) | 21 (1.3) | Yes |
| Exposure to environmental tobacco smoke | 25 (1.6) | Yes | |
| ISAAC phase II: current exposure | 439 (28.0) | ||
| ISAAC phase II: former exposure | 135 (8.6) | ||
| SOLAR I | 960 (61.2) | 6 (0.4) | Yes |
| Ever smokersƒ as indicated in SOLAR I | 480 (30.6) | 12 (0.8) | Yes |
| Having been breastfed | 1348 (85.9) | 12 (0.8) | Yes |
| Kindergarten attendance | 1550 (98.7) | 10 (0.6) | Yes |
| Presence of siblings | 1273 (81.1) | 13 (0.8) | Yes |
| Parental history of | |||
| Allergic rhinitis | 595 (37.9) | 138 (8.8) | Yes |
| Asthma | 166 (10.6) | 127 (8.1) | Yes |
| Atopic dermatitis | 304 (19.4) | 157 (10.0) | Yes |
| Positive skin prick test response in ISAAC phase II | 320 (23.7) | 221 (14.1) | No |
| Occupational exposure | 166 (10.6) | Yes## | |
| No risk | 624 (39.7) | ||
| Low risk | 383 (24.4) | ||
| High risk | 563 (35.9) |
Data are presented as n (%), unless otherwise stated. SOLAR: Study on Occupational Allergy Risks; ISAAC: International Study of Asthma and Allergies in Childhood. #: frequencies displayed for one random imputed data set; ¶: frequencies of missing values before imputation; +: age was dichotomised in two groups of comparable range (19–21 years and 22–24 years); §: mother or father qualified for university entrance or university diploma; ƒ: ≥1 pack-year, never-smoker defined as <1 pack-year until SOLAR I; ##: only missing time values were imputed to assess relevance of job regarding duration and intensity of potential occupational exposure; jobs lasting ≥4 weeks with ≥8 working hours per week were deemed relevant.