Response, mobility, and characteristics of the study population of Surveys 1 (1992–93), 2 (1995–96) and 3 (1998–99)
| Survey 1 | Survey 2 | Survey 3 | |
| Responders (questionnaire) | |||
| Total | 2470/2773 (89.1) | 2814/3765 (74.7) | 2348/3092 (75.9) |
| Zerbst | 857/971 (88.3) | 748/1090 (68.6) | 695/989 (70.3) |
| Bitterfeld | 799/918 (87.0) | 1255/1561 (80.4) | 961/1203 (79.9) |
| Hettstedt | 814/884 (92.1) | 811/1114 (72.8) | 692/900 (76.9) |
| Considered in analyses | |||
| Total | 2335/2773 (84.2) | 2517/3765 (66.9) | 2107/3092 (68.1) |
| Zerbst | 818/971 (84.2) | 674/1090 (61.8) | 631/989 (63.8) |
| Bitterfeld | 737/918 (80.3) | 1108/1561 (71.0) | 849/1203 (70.6) |
| Hettstedt | 780/884 (88.2) | 735/1114 (66.0) | 627/900 (69.7) |
| Demographic characteristics | |||
| Age | |||
| 5–7 yrs | 726/2335 (31.1) | 642/2517 (25.5) | 325/2107 (15.4) |
| 8–10 yrs | 750/2335 (32.1) | 855/2517 (34.0) | 757/2107 (35.9) |
| 11–14 yrs | 859/2335 (36.8) | 1020/2517 (40.5) | 1025/2107 (48.6) |
| Males | 1184/2335 (50.7) | 1354/2517 (53.8) | 1144/2107 (54.3) |
| Higher parental education# | 958/2272 (42.2) | 1010/2398 (42.1) | 812/2023 (40.1) |
| Other characteristics (predictors for adjustment) | |||
| Low birth weight¶ | 146/2240 (6.5) | 141/2373 (5.9) | 125/1881 (6.6) |
| No breastfeeding+ | 471/2321 (20.3) | 460/2498 (18.4) | 399/2004 (19.9) |
| Parental atopy | 620/2335 (26.6) | 770/2517 (30.6) | 647/2031 (31.9) |
| House made of concrete | 901/2245 (40.1) | 950/2447 (38.8) | 629/1929 (32.6) |
| Child shares bedroom | 1121/2297 (48.8) | 1028/2511 (40.9) | 665/2021 (32.9) |
| Dampness or visible moulds | 438/2312 (18.9) | 568/2506 (22.7) | 466/1998 (23.3) |
| Heating with single oven | 1150/2328 (49.4) | 931/2421 (38.5) | 751/1994 (37.7) |
| Carpet in child's room | 2173/2329 (93.3) | 2026/2479 (81.7) | 1845/2008 (91.9) |
| ETS exposure§ | 1076/2305 (46.7) | 1074/2489 (43.1) | 915/2084 (43.9) |
| Contact to cats | 750/2300 (32.6) | 815/2510 (32.5) | 722/2000 (36.1) |
| Child attended day-care centreƒ | 2062/2314 (89.1) | 2218/2499 (88.8) | 1764/2061 (85.6) |
Data are presented as respondents/total with % in parentheses
ETS: environmental tobacco smoke
#: education of father or mother ≥12 yr
¶: ≤2700 g
+: <4 weeks
§: current or prior
ƒ: before 1 yr of age