during 2004 to 2013, roof bolter

operators experienced 16 fatalities and 3,411 

nonfatal lost-time injuries, accounting for 

64.7% of injuries at underground coal mines 

[Sammarco et al. 2016].

Historically, lighting a roof bolter has been 

challenging given the machine’s size,

limited space for mounting lighting, low 

contrast levels, and excessive glare due to 

the workers’ close proximity to the machine 

lighting. To address these challenges, NIOSH 

researchers developed the Saturn LED area 

light with the main objectives of reducing 

glare and increasing floor illumination to 

improve the ability of miners to see floor

tripping hazards. A secondary objective 

was to reduce the size of the lighting 

to give more flexibility for mounting 

the lighting on roof bolters—thus, new 

mounting locations could potentially 

provide better illumination of hazards. 

The Saturn LED area light (Figure 1) 

takes up only one-third the volume 

compared to existing lights used on roof 

bolters, and it has a useful life of about 

30,000 hours in contrast to the existing 

Background 

Providing adequate lighting for miners 

to work safely is a significant challenge 

given that underground mines are one 

of the most difficult environments to

illuminate [Rea 2000]. Although a trend 

of increasing mine worker safety is 

evident, mining equipment-related 

fatalities and injuries are still at

unacceptable levels. As an example, 

Photo by NIOSH

Figure 1: The small size of the

Saturn LED area light enables greater

flexibility in machine mounting locations.

Summary

Researchers at the National

Institute for Occupational Safety 

and Health (NIOSH) have

developed the Saturn LED area

light that significantly improves

illumination for roof bolting

machines in underground mines, 

thereby enhancing safety by

reducing injuries to miners.

Providing better illumination

underground improves a miner’s 

ability to see and to avoid

potential hazards in the mine.

Results from NIOSH’s scientific

testing confirm that the Saturn

light enables major

improvements in trip hazard

detection and reduced glare when 

compared to the existing roof

bolter lighting. The Saturn area

light design is now freely

available for commercialization.

 By John J. Sammarco

The Saturn LED Area Light Provides Improved Illumination 

for Greater Roof Bolter Safety

No. 560 November 2017

Milestones in Mining Safety and Health Technology

NIOSH MINING PROGRAM

Technology News
Figure 2: The existing illumination provided by traditional lighting for a roof bolter (left). 

The improved illumination provided by the NIOSH-developed Saturn LED area light (right).Photos by J.H. Fletcher & Co.

lighting life of about 8,000 hours from traditional 

lighting. The longevity of the Saturn reduces the 

likelihood of maintenance-related injuries and 

reduces maintenance costs.

Approach

NIOSH conducted a comparative study of glare 

and visual performance for the detection of trip 

hazards using the traditional roof bolter lighting 

and the Saturn LED area light. A walk-thru roof 

bolter was used for the study. The roof bolter

light sources were compact fluorescent lamps 

shrouded by yellowish-orange polycarbonate 

globes intended to reduce glare and to protect

the lamps. The Saturn light used an array of 12 

cool-white LEDs that provide lighting similar to 

natural daylight. Thirty people participated in

the study, with ten people in each of the three

age groups: young 18–25 yrs. old; middle 40–50 

yrs. old; oldest > 50 yrs. old. The age group from

26 to 39 years was not included because there

are generally minimal changes in vision among 

those ages [Blanco et al., 2005]. Age is an

important factor because visual abilties generally 

decrease as age increases.

The well-established De Boer 9-level rating scale

[De Boer 1967] was used as a qualitative method for

determining discomfort glare. Visual performance was

quantified as the reaction time to detect a trip hazard,

where visual performance improves as the detection

time decreases. 

Findings

The unpublished results of the study indicated significant

reductions of discomfort glare and major improvements in

detecting trip hazards when using the Saturn LED area light

(Figure 2). Discomfort glare was improved up to three levels 

(from level 5 to 8). The De Boer 9-level rating scale for

discomfort glare ranges between level 9 (just noticeable)

and level 1 (unbearable). The mean trip hazard detection

time for the oldest age group (> 50 yrs. old) was improved

58% with the Saturn LED area light.

Notable Achievement

The NIOSH research team for the Saturn LED area light

won the 2017 NIOSH Bullard-Sherwood Research-to-Practice 

Award, which recognizes outstanding efforts by scientists

and their partners in applying occupational safety and

health research to prevent work-related injury, illness,

and death.

Availability

The NIOSH Saturn LED area light design documentation

package can be downloaded at

https://www.cdc.gov/niosh/mining/content/saturnarealight.html.

Acknowledgment

The NIOSH research team wishes to thank J.H. Fletcher & Co. for

access to the roof bolter used for this study.

References

Blanco M, Hankey J, and Dingus T [2005]. Phase II-Study 2: Visual

performance during nighttime driving in rain. In Enhanced Night

Visibility Series. U.S. Department of Transportation.

De Boer JB [1967]. Visual perception in road traffic and the field of

vision of the motorist. In Public Lighting, JB De Boer, ed. Eindhoven,

The Netherlands: Philips Tech. Library.

Rea MS (ed.) [2000]. IESNA lighting handbook: reference and

application, 9th ed. New York, NY: Illuminating Engineering Society

of North America.

Sammarco JJ, Podlesny A, Rubinstein E, Demich B [2016]. An analysis

of roof bolter fatalities and injuries in U.S. mining. Transactions of

the Society for Mining, Metallurgy, & Exploration. 340(1):11–20.

Accessible Version: https://www.cdc.gov/niosh/mining/content/saturn.html

For More Information

1-800-CDC-INFO (1-800-232-4636), 1-888-232-6348 (TTY), or request information at the CDC website at 

www.cdc.gov/info, or visit the NIOSH website at www.cdc.gov/niosh.

DHHS (NIOSH) Publication No. 2018–100

For more information on the Saturn area light, contact John Sammarco (412-386-4507, jsammarco@cdc.gov) or the NIOSH Mining Program

(mining@cdc.gov).

To receive NIOSH documents or for more information about occupational safety and health topics, contact:

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