Table 2 Characteristics of the follow up of the study cohort a
| Residents | Workers | |
|---|---|---|
| Total lung function and blood tests, n (%) | 1942 (33.7) | 3898 (66.2) |
| Measurements per person, a | 3.43 (1.5) | 4.7 (2.5) |
| Follow up, years, a | 3.0 (1.7) | 5.4 (3.3) |
| Months between measurements,a | 14.0 (4.8) | 16.5 (9.7) |