UNDERGROUND AND SURFACE 

MINING FACTS – 2004 

In 2004, data obtained from the Mine Safety and 

Health Administration (MSHA) indicated a total of 

891 underground (6.2%) and 13,587 surface (93.8%) 

mining operations.

1 

A total of 46,360 employees,

2 or 48,183 full-time 

equivalent (FTE)3 employees, were reported to 

MSHA as working at underground mining locations 

in 2004. This corresponded to 249,457 employees 

(or 222,839 FTE employees) that were reported as 

working at surface locations.4 

•	 Surface work location employee hours accounted 

for 82.2% of all hours reported to MSHA, while 

17.8% of employee hours were reported for 

underground work locations. 

0 

100 

200 

300 

400 

500 

600 

700

Number of Employee Hours

(millions)

Underground Work Locations 

Surface Work Locations 

All Work Locations 

1995	 1996 1997 1998 1999 2000 2001 2002 2003 2004 

• The majority of surface employee hours were for 

mine operator employees (83.4%) as opposed to 

independent contractor employees (16.6%). 

• Coal operators were the mining sector5

 reporting 

the most underground worker employee hours to 

MSHA (n=73,512,625; 76.3%). 

Of the 55 occupational mining fatalities reported to 

MSHA in 2004, 16 occurred at underground work 

locations, while 39 occurred at surface locations. 

• The fatality rate of 33.2 per 100,000 FTE 

employees was higher at underground work 

locations, compared to the rate of 17.5 for 

surface work locations. 

UG 

35% 

Surf 

65% 

Underground Surface 

Distribution of Mining Fatalities 

2000-2004 

Coal Operator Metal Operator 

Nonmetal Operator Stone Operator 

Sand & Gravel Operator Coal Contractor 

Noncoal Contractor 

Within underground work locations, 2,753 nonfatal 

lost-time injuries were reported, resulting in 

190,005 lost workdays.6 This compares to 5,386 

nonfatal lost-time injuries attributed to surface 

workers (total days lost = 273,334). 

•	 The overall underground nonfatal lost-time 

injury rate was greater than the surface injury 

rate (5.7 vs. 2.4 per 100 FTE workers). 

•	 The most frequent classifications of nonfatal 

lost-time injuries involved handling materials for 

both underground (n=851; 30.9%) and surface

(n=1,882; 34.9%) work locations. 

0 

2,000 

4,000 

6,000 

8,000 

10,000 

Number of Nonfatal Lost-time Injuries 

0 

2 

4 

6 

8 

10 

Nonfatal Lost-time Injury Rate

(per 100 Full-time Equivalent Employees) 

Underground 

Surface 

UG Rate 

Surf Rate 

1995	 1996 1997 1998 1999 2000 2001 2002 2003 2004 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention
 

National Institute for Occupational Safety and Health 

September 2007 
 

 

 

 

•	 The back was the most frequently reported part 

of the body injured at both underground (n=536; 

19.5%) and surface (n=1,163; 21.6%) work 

locations. These back injuries accounted for 

47,191 days lost from work at underground work 

locations and 63,271 days lost at surface 

locations in 2004. 

In 2004, 167 cases of occupational illnesses were 

reported at underground work locations.7 This compares to 259 cases reported for surface locations. 

•	 The majority of the reported illness cases were 

for joint, tendon, or muscle inflammation or 

irritation for both underground (n=81; 48.5%) 

and surface (n=115; 44.4%) work locations. 

Mining Characteristics, 2004 

Commodity and 

Type of Employer 

Coal Operator 

Metal Operator 

Nonmetal Operator 

Stone Operator 

Sand & Gravel Operator 

No. of Mines 

No. of 

Employees 

UG Surf 

No. of FTE 

Employees 

UG Surf 

Fatality Rate 

Nonfatal 

Lost-time 

Injury Rate 

UG Surf UG Surf UG Surf

646 1,365 

74 177 

46 695 

125 4,276 

-- 7,074 

33,490 39,534 

3,905 21,300 

2,289 17,143 

1,768 66,649 

-- 37,000 

36,756 43,313 

3,810 22,281 

2,441 17,742 

1,950 69,203 

-- 33,364 

35.4 23.1 

26.2 4.5 

41.0 --

-- 11.6 

-- 24.0 

6.1 2.0 

3.4 1.9 

3.4 2.6 

3.9 3.2 

-- 2.3 

Operator Total 891 13,587 41,452 181,626 44,957 185,902 33.4 14.5 5.7 2.6 

Coal Contractor 

Noncoal Contractor 

-- --

-- --

3,697 26,531 

1,211 41,300 

2,334 15,630 

892 21,306 

42.8 25.6 

-- 37.5 

7.8 1.8 

2.8 1.6 

Contractor Total -- -- 4,908 67,831 3,226 36,936 31.0 32.5 6.4 1.7 

TOTAL 891 13,587 46,360 249,457 48,183 222,839 33.2 17.5 5.7 2.4 

Data may not add to totals due to independent rounding. Number of employees was rounded at the subunit level of each mine to be consistent with 

MSHA reporting. Fatality rates were computed per 100,000 FTE employees. Nonfatal lost-time injury rates were computed per 100 FTE employees. 

Notes: All analyses exclude office employees. Further statistical methodology is available on the NIOSH Internet 

[http://www.cdc.gov/niosh/mining/statistics/method.htm]. 1

When classifying mining operations as either underground or surface, the mines reporting employment for the subunit "Surface 

 Operations at Underground Mines" were counted as underground mines. Mining operations reporting only office employees were

 determined to be underground or surface based on the reported mine type. Mines at which only independent contractors were working 

did not show any employment and were not counted. 

2

Number of employees is the average number of persons working at individual establishments during calendar quarters of active 

operations. Employment numbers were rounded at the subunit level of each mine to be consistent with MSHA reporting. 3

Full-time equivalent employees were computed using reported employee hours (2,000 hours = 1 FTE). 

4

Surface work locations include surface operations at underground mines (surface shops and yards, tipple physically located at the mine 

site), surface operations (strip or open pit mines including associated shops and yards), auger mining operations, culm banks 

(reworking of mine dumps or refuse pile), dredge (mining operations conducted from a platform floating on water), other surface 

operations (brine pumping, etc.), independent shops and yards not associated with a specific mine, and mill or preparation plant. 5

Mining sectors: coal operators, metal operators, nonmetal operators, stone operators, sand and gravel operators, coal contractors, and

 noncoal contractors. 

6

Includes actual days away from work and/or days of restricted work activity. For permanently disabling injuries only, statutory days 

charged by MSHA were used if they exceeded the total lost workdays. 7

Because of the complexity of attributing disease causation to the workplace, occupational illnesses may be underreported. 

To receive NIOSH documents or for more information about 

occupational safety and health topics, contact NIOSH at 

1–800–CDC–INFO (1–800–232–4636) 

1–888–232–6348 (TTY) 

e-mail: cdcinfo@cdc.gov 

or visit the NIOSH Web site at http://www.cdc.gov/niosh 

DHHS (NIOSH) Publication No. 2007–174