| Characteristics | Control subjects (n=) | Experimental subjects (n=) |
| Age (years) | 33 | 35 |
| Sex Male Female |
82 130 |
129 99 |
| Duration of working hours in the test environment (hours) | - | 8 |
| Years of Exposure 1 - 5 6 - 10 <10 |
- - - |
103 73 52 |
| Areas of work in the test environment Power plants Offices Others |
- - - |
83 76 70 |