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| Ventilation system | Number of buildings | Mean (SE) symptom score in the building* |
|---|---|---|
| Mechanical ventilation | 2 | 1.74 (0.26) |
| Natural ventilation | 23 | 2.12 (0.09) |
| All air system | 10 | 2.07 (0.11) |
| Central induction | 6 | 2.21 (0.09) |
| Local induction | 3 | 2.20 (0.24) |
| p = 0.8 |
*Estimates are adjusted for age, sex, and employment grade using a regression model.
