Table 1.
Demographics and characteristics for all 50 study participants.
| Individual Characteristics | N | % |
| Male | 50 | 100 |
| Whites | 44 | 88 |
| 1Smokers | 18 | 36 |
| Other Characteristics | ||
| 2Time of ECG (AM) | 36 | 72 |
| 3Season of ECG (winter) | 21 | 42 |
| 4Heart problems | 10 | 20 |
| Mean | s.d. | |
| Age at ECG measurement (years) | 39 | 11 |
| Age at becoming a boilermaker (years) | 32 | 9 |
| Length of follow up (years) | 7 | 6 |
| 5Last Weld Day before study (days) | 36 | 37 |
1
Current Smokers vs Non-smokers and Previous smokers
2
Morning (AM) vs Afternoon(PM)
3
Winter vs Summer
4
Heart problems include reported previous history of arrhythmia, cardiac sinus problems, or palpitations
5
One participant had not welded for 3 years and was not included in this statistic