No matter what industry you work in, stress is an unwelcome part of any occupation. A recent study by Chicago-based employee assistance provider ComPsych deemed "unclear expectations from supervisors" as the most stressful part of any job. The study focused specifically on stress in the workplace during times of change. Of course, that notes just one source of workplace stress people face every day.

>>READ: These are the 30 least stressful jobs

With these types of daily challenges in mind, CareerTrends found the 28 most stressful jobs in America using data from O*NET, an occupational database sponsored by the U.S. Department of Labor. O*NET assigns scores in various categories for each occupation based on the results to survey questions sent out to employers.

In examining the jobs that landed on the list, we found there was no correlation between total stress score and average salary. Unfortunately for these employees, working the most stressful job doesn’t guarantee the biggest payout.

For this list, we focused on three different scores, all graded on a 1 to 5 scale: frequency of conflict situations, exposure to hazardous conditions, and stress tolerance. Only jobs with at least 10,000 total employees were included.

These three grades were combined to create a “total stress score,” and the occupations with the highest total stress scores were chosen for this list:

Frequency of conflict situations: How often are there conflict situations the employee has to face in this job?

Exposure to hazardous conditions: How often does this job require exposure to hazardous conditions?

Stress tolerance: Job requires accepting criticism and dealing calmly and effectively with high stress situations.

Note: In the event of ties, the job with the higher stress tolerance score was ranked higher on the list.

28. Automotive specialty technician

Average annual salary: $34,092
Total employment: 633,390

Total stress score: 11.33
Conflict frequency: 3.3
Hazard exposure: 4.21
Stress tolerance: 3.82

27. Forest fire fighting supervisor

Average annual salary: $60,372
Total employment: 59,870

Total stress score: 11.34
Conflict frequency: 3.08
Hazard exposure: 3.76
Stress tolerance: 4.5

26. Airline pilot

Average annual salary: $98,733
Total employment: 75,760

Total stress score: 11.35
Conflict frequency: 3.37
Hazard exposure: 3.17
Stress tolerance: 4.81

25. Anesthesiologist assistant

Average annual salary: $89,300
Total employment: 91,670

Total stress score: 11.41
Conflict frequency: 3.37
Hazard exposure: 3.12
Stress tolerance: 4.92

24. Power-line installer

Average annual salary: $62,094
Total employment: 114,540

Total stress score: 11.44
Conflict frequency: 3.12
Hazard exposure: 4.6
Stress tolerance: 3.72

23. Fire investigator

Average annual salary: $53,376
Total employment: 11,370

Total stress score: 11.44
Conflict frequency: 3.43
Hazard exposure: 3.56
Stress tolerance: 4.45

22. Flight attendant

Average annual salary: $42,022
Total employment: 98,510

Total stress score: 11.44
Conflict frequency: 3.99
Hazard exposure: 2.77
Stress tolerance: 4.68

21. Geothermal technician

Average annual salary: $36,126
Total employment: 138,460

Total stress score: 11.46
Conflict frequency: 2.83
Hazard exposure: 4.67
Stress tolerance: 3.96

20. Subway operator

Average annual salary: $54,471
Total employment: 11,300

Total stress score: 11.47
Conflict frequency: 3.63
Hazard exposure: 3.34
Stress tolerance: 4.5

19. Medical laboratory technologist

Average annual salary: $54,678
Total employment: 161,710

Total stress score: 11.48
Conflict frequency: 2.98
Hazard exposure: 4.17
Stress tolerance: 4.33

18. Pump operator

Average annual salary: $41,643
Total employment: 12,170

Total stress score: 11.56
Conflict frequency: 2.85
Hazard exposure: 4.2
Stress tolerance: 4.52

17. Oil drill operator

Average annual salary: $50,061
Total employment: 26,480

Total stress score: 11.57
Conflict frequency: 3.29
Hazard exposure: 4.2
Stress tolerance: 4.08

16. Elevator installer

Average annual salary: $68,792
Total employment: 20,590

Total stress score: 11.66
Conflict frequency: 2.67
Hazard exposure: 4.93
Stress tolerance: 4.06

15. Stationary engineer

Average annual salary: $48,323
Total employment: 37,550

Total stress score: 11.69
Conflict frequency: 3.21
Hazard exposure: 4.55
Stress tolerance: 3.93

14. Petroleum pump operator

Average annual salary: $54,492
Total employment: 41,700

Total stress score: 11.7
Conflict frequency: 2.77
Hazard exposure: 4.9
Stress tolerance: 4.03

13. Conveyor operator

Average annual salary: $31,891
Total employment: 38,830

Total stress score: 11.72
Conflict frequency: 3.17
Hazard exposure score: 4.3
Stress tolerance: 4.25

12. Correctional officer supervisor

Average annual salary: $56,184
Total employment: 45,150

Total stress score: 11.72
Conflict frequency: 4.46
Hazard exposure: 2.86
Stress tolerance: 4.4

11. Powerhouse equipment installer

Average annual salary: $67,128
Total employment: 22,120

Total stress score: 11.73
Conflict frequency: 2.84
Hazard exposure: 4.75
Stress tolerance: 4.14

10. Police supervisor

Average annual salary: $68,973
Total employment: 101,420

Total stress score: 11.74
Conflict frequency: 4.17
Hazard exposure: 2.81
Stress tolerance: 4.76

9. Refrigeration mechanic

Average annual salary: $40,601
Total employment: 261,390

Total stress score: 11.93
Conflict frequency: 3.29
Hazard exposure: 4.72
Stress tolerance: 3.92

8. Gas derrick operator

Average annual salary: $45,966
Total employment: 20,760

Total stress score: 11.93
Conflict frequency: 3.38
Hazard exposure: 4.62
Stress tolerance: 3.93

7. Nurse anesthetist

Average annual salary: $147,256
Total employment: 36,590

Total stress score: 11.93
Conflict frequency: 3.97
Hazard exposure: 3.03
Stress tolerance: 4.93

6. Power plant operator

Average annual salary: $62,908
Total employment: 40,300

Total stress score: 11.94
Conflict frequency: 2.94
Hazard exposure: 4.8
Stress tolerance: 4.2

5. Furnace operator

Average annual salary: $34,012
Total employment: 20,590

Total stress score: 11.98
Conflict frequency: 3.59
Hazard exposure: 4.72
Stress tolerance: 3.67

4. Forest firefighter

Average annual salary: $38,890
Total employment: 308,790

Total stress score: 12.08
Conflict frequency: 3.61
Hazard exposure: 4.08
Stress tolerance: 4.39

3. Police patrol officer

Average annual salary: $47,819
Total employment: 638,810

Total stress score: 12.09
Conflict frequency: 4.56
Hazard exposure: 2.85
Stress tolerance: 4.68

2. Quality control manager

Average annual salary: $88,381
Total employment: 167,200

Total stress score: 12.11
Conflict frequency: 3.92
Hazard exposure: 3.61
Stress tolerance: 4.58

1. Continuous mining machine operator

Average annual salary: $43,099
Total employment: 11,540

Total stress score: 12.21
Conflict frequency: 3.25
Hazard exposure: 4.9
Stress tolerance: 4.06