Summary

Workers in underground 

stone mines have a high 

fatality rate caused by 

falls of ground from the 

mine roof or rib. NIOSH 

recommendations to reduce ground fall injuries 

and deaths address baskets, mechanical scalers, 

mechanical bolters, drill 

steel changing, personal 

protective equipment, and 

training.

workers with minimal knowledge of the hazardous conditions that exist underground.

Workers in underground stone 

mines have a fatality rate nearly 20 times that of workers in 

the manufacturing sector. Three 

quarters of the fatalities in 

underground stone mines are 

caused by falls of ground from 

the mine roof or rib (Figure 1) [Statistical Abstract of 

the United States 1985–1999; 

MSHA 1983–1999]. During 

1983–1999, nonfatal ground 

falls resulted in 140 injuries, or 

15% of all underground, losttime stone mine injuries. These 

nonfatal ground fall injuries resulted in more than 13,800 lost 

workdays (one third of all lost 

workdays). Ground falls generate more disabling injuries and 

time away from work than any 

other type of incident.

Ground Fall Injuries in

Underground Stone Mines

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Figure 1. Large roof fall at underground limestone mine.

Description of

Exposure

An informal National Institute for Occupational Safety 

and Health (NIOSH) review 

in 1998 identified approximately 17 new underground 

limestone operations in various stages of planning; as many 

as 35 new underground stone 

mines are expected by 2005. 

Many of these new underground stone mines will employ new or inexperienced 
Because of the high ground fall fatality rate 

and high number of lost workdays from injuries, NIOSH examined the Mine Safety and Health 

Administration (MSHA) accident and employment databases for worker activity at the time 

of injury for the period 1983–1999 (mine 

worker activity codes and accident narratives) 

[MSHA 1983–1999]. During this period, 156 

injuries (both fatal and lost-time) related to 

ground falls were reported. These incidents included all roof and rib falls listed in the database as well as incidents classified as machinery, 

for which the source of injury was caving rock. 

The frequency of ground fall injuries was associated with worker activities as follows: scaling 

activities, 47%; handling explosives, 24%; other 

activities, 10%; roof bolting, 8%; drilling face, 

6%; and handling supplies, 5%.

Injury and Fatality Review

To identify work practices for improving the safety of miners, the MSHA injury narratives and fatal accident reports noted above were reviewed 

for each lost-time and fatal ground fall injury (includes mines with bolted and unbolted roofs). 

The results are summarized by the type of work 

activity at the time of the ground fall.

§ Scaling was the most common worker activity at the time of a ground fall; almost one 

half of all ground falls were related to scaling. Nearly a third of the scaling incidents 

were associated with roof or rib rock falling 

onto the basket, scaling machine, or outrigger equipment used to reach the remote areas of the mine. The jarring of the basket or 

scaling machine caused by the falling rock often caused workers to fall from the basket or 

against the basket rail.

According to one incident narrative, two miners were hand scaling the roof from a bucket 

when a large rock dislodged and struck the corner of the bucket. The weight of the rock on 

the bucket caused the boom of the scaling rig 

to bend toward the mine floor until the rock 

fell to the floor. The boom then catapulted upward, throwing the two scalers from the bucket. A second narrative described a worker who 

was hand scaling while leaning out of a basket. 

When a massive slab of rock fell and struck the 

outrigger of the scaling machine, it caused the 

machine to fall on its side. The worker was 

thrown from the basket, but a harness apparently prevented the worker from being thrown 

to the floor or crushed by the machine. The 

worker suffered a fractured skull.

§ Handling explosives accounted for a high 

number of lost-work-time injuries from ground 

falls. Most of these incidents occurred while 

the worker was loading explosives into the 

hole. These incidents resulted in injury to the 

victim’s neck, back, or shoulder from small 

rock pieces that fell from the mine face and 

roof. Two fatalities from ground falls occurred 

while a miner was cleaning out bottom holes. 

According to the MSHA [1983–1999] fatality 

report, the workers routinely cleaned the bottom holes before entering the basket and going 

up to check the roof. They relied entirely on visual inspection of roof conditions.

§ Roof bolting activities involving ground fall 

injuries accounted for more than twice the 

typical number of days lost per incident for 

all underground stone mine incidents. Miners working from a basket to install the bolts 

have more injuries than miners using an automated bolter.

§ Drilling the face accounted for the highest 

number of days lost per incident of all worker activities. MSHA face drilling operation 

narratives indicated that in at least 75% of 

the drilling incidents, the victim was outside 

the cab. In most instances, the victims were 

changing drill steel or checking the drill alignment.
§ Miscellaneous activities account for more 

than 40% of fatal ground fall injuries. The 

MSHA fatality reports were reviewed to find 

other causes [MSHA 1986–1996]. Four of the 

seven recorded fatalities occurred while the 

victims were entering a recently blasted face 

area. These fatalities resulted from the fall of 

roof or face loosened by the recent blast. In two 

of the cases, MSHA was unable to determine 

why the victims had entered the blast area.

Controls

The following measures are recommended 

to reduce ground fall injuries in underground 

stone mines:

§ Minimize scaling injuries that occur from the 

impact of rock falling onto the basket or lift:

— Make sure that safety harnesses and hard 

hats with chin straps are used correctly 

during scaling operations.

— Fasten harnesses to structurally secure 

locations on the basket with proper rope 

length to minimize the momentum of 

the fall.

— Provide proper training in putting on a 

harness and operating the basket manually in case the hydraulic system is damaged because of a ground fall or malfunction.

§ Equip baskets that are used for scaling and 

roof bolting with padded railings and a canopy or caging to absorb and deflect ground 

falls. Ensure that canopies are convenient to 

workers and that they allow easy access to 

the roof. If possible, use a retractable canopy 

with a partially removable roof section.

§ Use mechanical scalers with protective cabs 

instead of hand scaling if possible.

§ Use personal protective equipment such as 

a hard hat with a back rim (similar to a fire 

fighters helmet) to help deflect small rock 

pieces from hitting the neck and back while 

loading explosives. In severe conditions, use 

flack jackets or padding devices worn by athletes for additional protection for the back 

[Grau and Prosser 1997].

§ When roof bolting, use mechanical bolters 

with a protective cab if possible.

§ Move the location for changing the drill steel 

away from the drilled face to an area where 

the rib and roof are stable.

§ Use hazard training to emphasize the severe ground fall risk associated with a freshly 

blasted mine face and the proper procedures 

for entering the area.

§ Develop a complete checklist of all critical 

safety procedures related to ground falls that 

can be used as a training tool.

Acknowledgments

The principal contributors to this publication 

were Deno Pappas and Leonard Prosser, Pittsburgh Research Laboratory, National Institute 

for Occupational Safety and Health.

References

Grau III RH, Prosser LJ [1997]. Scaling accidents in underground stone mines. Rock Products, January, pp. 39–

41.

MSHA [1983–1999]. Quarterly employment and coal 

production: accidents/injuries/illnesses reported to MSHA 

under 30 CFR Part 50. Denver, CO: U.S. Department of 

Labor, Mine Safety and Health Administration, Office of 

Injury and Employment Information.

MSHA [1986–1996]. Accident investigation reports: fatal 

fall of face; fatal fall of roof. November 24, 1986; November 25, 1991; August 4, 1992; March 3, 1993; November 

4, 1993; May 10, 1996. Washington, DC: U.S. Department 

of Labor, Mine Safety and Health Administration.

Statistical Abstract of the United States [1985–1999]. 

Washington, DC: U.S. Census Bureau.

Safer • Healthier • PeopleTM
DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

4676 Columbia Parkway

Cincinnati, OH 45226–1998

November 2003

For More Information

NIOSH research on ground fall injuries in underground stone mines has been published in a journal:

Pappas DM, Prosser LJ [2001]. An overview of 

groundfall injuries and worker activity in underground 

stone mines. Falls Church, VA: Joseph A. Holmes 

Safety Association Bulletin, August, pp. 8–14.

To receive more information about occupational safety and health topics, contact NIOSH at

NIOSH

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This document is in the public domain and may be 

freely copied or reprinted. NIOSH encourages all 

readers of the Workplace Solutions to make them 

available to all interested employers and workers.

As part of the Centers for Disease Control and Prevention, NIOSH is the Federal agency responsible for 

conducting research and making recommendations to 

prevent work-related illnesses and injuries. All Workplace Solutions are based on research studies that 

show how worker exposures to hazardous agents or 

activities can be significantly reduced.

DHHS (NIOSH) Publication No. 2004–106

Ground Fall Injuries in Underground Stone Mines