Demographic, exposure and clinical characteristics of study participants
| Participants | 272 | |
| Demographics | ||
| Age, years# | 46.9±13.6 | |
| Male | 248 (91) | |
| BMI, kg·m−2# | 29.6±6.0 | |
| Ever smokers | 173 (64) | |
| Smoking pack-years | 3 (0–16.4) | |
| Caucasian ethnicity | 219 (81) | |
| Educational qualifications | ||
| Grade school | 8 (3) | |
| High school | 36 (13) | |
| Trade school | 128 (47) | |
| College/university | 100 (37) | |
| Marital status | ||
| Single/unmarried | 82 (30) | |
| Married/with a partner | 172 (63) | |
| Divorced/separated/widowed | 18 (7) | |
| Exposure history | ||
| Childhood smoke exposure | 182 (67) | |
| Parental lung condition | 74 (27) | |
| Exposure to mineral fibres# | 259 (95) | |
| Use of PPE for mineral fibres# | 161 (59) | |
| Clinical profile | ||
| Episodes of chest infection in the past 3 years¶,+ | 2 (1–2) | |
| White blood cell profile | Baseline | Follow-up+ |
| Neutrophil % | 58±10 | 59±10 |
| Eosinophil % | 3±2 | 3±2 |
| Lymphocyte % | 30±8 | 30±9 |
| Monocyte % | 8±2 | 8±2 |
| Lymphocyte/monocyte ratio§ | 3.84±1.31 | 3.76±1.45 |
| Neutrophil/lymphocyte ratio§ | 2.26±1.45 | 2.31±1.19 |
Data are presented as mean±sd or median (interquartile range) for numerical variables, and n (%) for categorical variables. BMI: body mass index; PPE: personal protective equipment. #: data taken at the baseline visit; ¶: data taken at the follow-up visit; +: median interval between baseline and follow-up visit was 3.8 years; §: ratio of absolute count.