Table 1.
Characteristics of the study participants
| Office workers | Truck drivers | p-value a | |
|---|---|---|---|
| (n = 60) | (n = 60) | ||
| Sex, n (%) | |||
| Male | 40 (66.7) | 40 (66.7) | |
| Female | 20 (33.3) | 20 (33.3) | 1.00 |
| Smoking, n (%) | |||
| Never smoker | 35 (58.3) | 34 (56.7) | |
| Former | 2 (3.3) | 2 (3.3) | |
| Current | 23 (38.3) | 24 (40.0) | 1.00 |
| Age [years], mean (SD) | 30.3 ± 8.0 | 33.5 ± 5.7 | 0.01 |
| BMI [kg/m 2 ], mean (SD) | 22.8 ± 3.4 | 24.3 ± 3.2 | 0.01 |
| Time spent commuting to work, mean (SD) | 6.9 ± 9.0 | 12.4 ± 15.2 | <0.001 |
| Cigarettes smoked during examination time, mean (SD) b | 0.5 ± 1.7 | 2.3 ± 4.2 | 0.003 |
| Work hours per week, mean ± SD | 50.6 ± 11.0 | 67.3 ± 14.0 | <0.001 |
| Study day of the week, n (%) | |||
| Monday | 16 (13.3) | 19 (15.8) | |
| Tuesday | 18 (15.0) | 13 (10.8) | |
| Wednesday | 14 (11.7) | 15 (12.5) | |
| Thursday | 15 (12.5) | 20 (16.7) | |
| Friday | 17 (14.2) | 19 (15.8) | |
| Saturday | 18 (15.0) | 16 (13.3) | |
| Sunday | 22 (18.3) | 18 (15.0) | 0.8c |
| Average temperature on two study days, mean (SD) | 25.4 ± 2.5 | 25.3 ± 2.5 | 0.96c |
| Average dew point on two study days, mean (SD) | 20.6 ± 2.1 | 20.6 ± 2.1 | 0.93c |
aP-values were calculated using Student’s t-test and Fisher’s exact test for continuous and categorical variables, respectively.
bOnly current or former smokers.
cCumulative of the two study days. Based on 240 total observations (120 study days for office workers and 120 study days for truck drivers). P-values were obtained from mixed-effects regression models.