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Number of CSO events occurring <500 m of residence during the 24 possible exposure days (three exposure periods—one case and two controls, each of eight days long).
| CSO events n | Total children n (%) |
|---|---|
| 0 | 492 (14%) |
| 1 | 365 (10%) |
| 2 | 388 (11%) |
| 3 | 390 (11%) |
| 4 | 395 (11%) |
| 5 | 366 (10%) |
| 6 | 268 (7%) |
| 7 | 223 (6%) |
| 8 | 150 (4%) |
| 9 | 111 (3%) |
| 10 | 93 (3%) |
| 11 | 64 (2%) |
| ≥12 | 337 (9%) |
