| Office workers | Truck drivers | p-value a |
---|---|---|---|
 | (n=60) | (n=60) |  |
Age [years], mean ± SD | 30.27 ± 7.96 | 33.53 ± 5.65 | 0.01 |
Sex, n (%) | Â | Â | Â |
      Male | 40 (66.67) | 40 (66.67) |  |
      Female | 20 (33.33) | 20 (33.33) | 1.00 |
BMI [kg/m 2 ], mean ± SD | 22.76 ± 3.38 | 24.27 ± 3.21 | 0.01 |
Smoking, n (%) | Â | Â | Â |
      Never smoker | 35 (58.33) | 34 (56.67) |  |
      Former | 2 (3.33) | 2 (3.33) |  |
      Current | 23 (38.33) | 24 (40) | 1.00 |
Pack-years of smoking, mean ± SD b | 1.2 ± 2.7 | 5.1 ± 9.3 | 0.003 |
Work hours per week, mean ± SD | 50.6 ± 11.0 | 67.3 ± 14.0 | <0.001 |
Day of the week on the two study days, n (%) | Â | Â | Â |
      Monday | 16 (13.33) | 19 (15.83) |  |
      Tuesday | 18 (15) | 13 (10.83) |  |
      Wednesday | 14 (11.67) | 15 (12.5) |  |
      Thursday | 15 (12.5) | 20 (16.67) |  |
      Friday | 17 (14.17) | 19 (15.83) |  |
      Saturday | 18 (15) | 16 (13.33) |  |
      Sunday | 22 (18.33) | 18 (15) | 0.88c |
Average temperature on the two study days, mean ± SD | 25.36 ± 2.51 | 25.34 ± 2.51 | 0.96c |
Average dew point on the two study days, mean ± SD | 20.63 ± 2.06 | 20.61 ± 2.13 | 0.93c |