| Respiratory symptoms on screening questionnaire (n = 454)* | Controls: asymptomatic on screening questionnaire (n = 48) | |||||
| Work-related n (%) | Not work-related n (%) | Total n (%) | Work-related n (%) | Not work-related n (%) | Total n (%) | |
| MRC Breathlessness | ||||||
| MRC1: Troubled by shortness of breath when hurrying on level ground or walking up a slight hill | 146 (17.5%) | 77 (9.2%) | 223 (26.7%) | 2 (4%) | – | 2 (4%) |
| MRC2: Short of breath walking with other people of own age and sex on level ground | 89 (10.6%) | 41 (4.9%) | 130 (15.5%) | 1 (2%) | – | 1 (2%) |
| MRC3: Had to stop for breath when walking at own pace on level ground | 41 (4.9%) | 17 (2%) | 58 (6.9%) | – | – | – |
| MRC4: Short of breath washing or dressing | 16 (1.9%) | 7 (0.8%) | 23 (2.7%) | – | – | – |
| MRC Chronic Bronchitis | ||||||
| MRC chronic bronchitis: sputum production for 3 months each year for 2 years or more | 78 (9.3%) | 53 (6.3%) | 131 (15.6%) | – | – | – |
| Asthma type symptoms | ||||||
| In last 12 months has your chest ever felt tight or your breathing become difficult? | 156 (18.6%) | 100 (12.0%) | 256 (30.6%) | – | 2 (4%) | 2 (4%) |
| In the past 12 months have you had wheezing or whistling in your chest? | 122 (14.6%) | 105 (12.6%) | 227 (27.2%) | – | 2 (4%) | 2 (4%) |
| Humidifier fever type symptoms | ||||||
| In the past 12 months have you suffered recurrent flu-like symptoms on five or more occasions? (Work-relatedness was defined as symptoms at the beginning of the working week and/or being more frequent/severe on returning to work after a weekend or holiday) | 18 (2.1%) | 13 (1.6%) | 31 (3.7%) | – | – | – |
*Note that the total workforce of 836 used as denominator.