When examining nail gun injuries, and trying to prevent them, and/or reduce their frequency and severity, an epidemiologic approach can be used. This approach looks and the interaction between the environment, the nail gun user, and the nail gun. One tool that is used is called the Haddon’s Matrix, developed by William Haddon in 1970. The matrix lays out factors that contribute to an injury, in pre-event, event, and post-event phases, to help pinpoint intervention areas (See Table). [14]
Factors |
Phases |
Human |
Equipment |
Environment |
Physical |
Social |
Pre-Event |
· Experience level
· Skill level
· Training
· Knowledge of correct work practices
· Awkward postures
· Level of concentration
· Able to speak/read English |
· Trigger type
· Safety mechanism function and use
· Type of materials being used
· Defective equipment
· Safety warnings and directions present |
· Weather conditions
· Construction and building activity
· Work at heights
· Skill of other employees
· Distractions
· Jobsite housekeeping |
· Manufacturers decisions on trigger type
· Type of trigger shipped with gun
· Knowledge of employer on nail gun risks
· Time spent training employees
· Union vs. non-union
· Commercial vs. residential construction |
Event |
· Use of PPE
· Knowledge of potential causes of gun ( mis)fire
· How to hold and position hands and body |
· Correct and non-defective PPE
· Safety mechanism
· Trigger type
· Power of the gun |
· Weather conditions
· Size of work area
· Proximity of co-workers |
· Available resources, knowledge, or concern on part of employers and employees
· Inadequate nail gun maintenance, training, or PPE |
Post-Event |
· Pain tolerance
· Health status
· Severity of injury
· Location of injury
· Infection
· Lost work time and financial strain
· Emotional damage |
· Nail depth
· Nail structure
· Adhesives or coatings |
· Distance to medical care
· Hand specialist available
· Specialty care available
· Rehabilitative care available |
· Emphasis on injury reporting
· Emphasis on seeking medical care
· Proper care
· Follow-through with care instructions
· Increased medical and workers' compensation rates for employers |
Total Losses/Cost |
Damage to People |
Damage to Equipment |
Damage to Physical Environment |
Damage to Society |
Haddon's Matrix Applied to Nail Gun Injuries
In addition to the matrix, Haddon also developed 10 strategies for injury prevention and control, occurring in the different phases of the injury, to be used for systematic consideration of how to prevent or reduce the impact of any type of injury. There are prevention and control measures that are particularly warranted or successful for nail gun injuries, and several of Haddon’s 10 strategies are particularly applicable. [14] Using the hierarchy of control, engineering strategies are considered first, followed by legislative and administrative, training, and finally personal protective equipment.
Engineering Controls
1. Prevent the Creation of the Hazard in the First Place:
3. Prevent the Release of the Hazard that Already Exists:
4. Modify the Rate or Spatial Distribution of the Hazard From its Source:
7. Modify the Basic Relevant Qualities of the Hazard:
Using engineering control approaches before injuries occur is the best way for prevention, and many of Haddon’s strategies are applicable. Since nail guns will not be eliminated, the next best option is to eliminate the contact trigger through a variety of methods. There is a high prevalence of contact triggers out in the work field, and switching to sequential triggers from contact triggers will produce a substantial decrease in the rate of injury. [6] The majority of nail gun manufacturers offer the sequential trip option on new guns or have kits that will retrofit old guns to sequential triggers. [1] However, the most effective, option would be for manufacturers to stop making contact trip triggers all together, and switch to only making sequential trip triggers. Additionally, safety components should not be made to allow the user to turn them off or override them and turn the gun onto “bounce” or rapid fire mode. Nail gun manufacturers can also make substantial improvements in the weighting, balance, and center of gravity of guns to reduce the risk for nail gun injuries.
Legislative and Administrative Controls
2. Reduce the Amount of Hazard Brought into Being:
4. Modify the Rate or Spatial Distribution of the Hazard From its Source:
Standards, regulations, and policy changes should be used to complement engineering controls to reduce nail gun injuries. A voluntary ANSI standard is not effective enough to promote the change to the sequential trigger, and contact triggers should not be allowed to be shipped in the same box when a new gun is ordered. Mandatory safety or manufacturing requirements need to be in place to force the sequential trigger to the industry norm. Regulations should also define minimum training requirements that would be needed for someone to be adequately aware of hazards, able to recognize hazards, and safely handle and use a nail gun. Vendors and dealers should be held accountable for training and safe use of their products.
Training
3. Prevent the Release of the Hazard that Already Exists:
5. Separate, in Time or Space, the Hazard and that which is to be Protected:
8. Make what is to be Protected more Resistant to the Hazard
Vendors and manufacturers need to ensure instruction and procedures reach end-user, especially in the case of a sale or rental to users unfamiliar with nail guns. Nail gun use should never be assumed to be an unskilled task and training should not be limited to just how to operate and upkeep the tool. Training on proper techniques, safety features, and work practices, such as never pointing the gun at others, not moving around the site with a finger on the trigger, and proper hand placement and body position prevents injuries. It makes people more aware and keeps them out of the direct line of fire in case of accidental discharge or misfire. People also need to know in which situations over penetrations of the materials are likely, and which materials and properties of the materials would make ricochet likely. [4, 6] More training is better, and the best type of training is classroom combined with hands-on. [11]

Strained Overhead Position, and Co-Worker in Direct Line of Fire in the Event of Over-Pentration of Wood

Work at Heights, Potential for Trips, Slips, or Fall, and Employee has Finger on the Trigger When Not Firing Gun
Training should specifically target younger and less experienced employees. Since the nail gun is easy to use, it is often given to these employees soon after coming on the job, so early and immediate training is needed to prevent injuries. [6]
Currently, the value and injury reduction of training is only half as effective as changing from contact to sequential trigger, however, as sequential triggers become more commonplace, the impact of proper and effective training on injury reduction will become more noticeable. [6]
Personal Protective Equipment
6. Separate the Hazard and that which is to be Protected by Interposition of a Material Barrier:
8. Make what is to be Protected more Resistant to the Hazard
Regardless of trigger type, appropriate personal protective equipment (PPE) should always be worn on the jobsite or when working with or around nail guns. In the event of an unintentional or misdirected discharge of a nail, safety glasses and steel toe boots or heavy work shoes will protect the employee from serious injury, or prevent the injury all together from the parts of the body that are shielded. Eye protection is especially important due to the catastrophic nature of eye injuries. Hearing protection is also necessary due to possibility of exceeding allowable noise limits with prolonged nail gun use.
After an Injury
9. Begin to Counter the Damage Already Done by Environmental Hazards:
10. Stabilize, Repair, and Rehabilitate the Object of Damage:
Special emphasis needs to be made to employees on reporting nail gun injuries and seeking timely medical care. All nail gun injuries should be professionally cleaned, and more severe injuries to the hand should be referred to a hand specialist. All follow-up care and rehabilitative directions must be followed.
Continued Data and Research Needs
After examining the nail gun injury problem and using an epidemiologic approach to look at interactions of many various factors, there are clearly some areas that require more attention. One area is the continued emphasis on removing the contact trigger from the market, through a combination of engineering controls, legislation, and overall user education. A second area is the accurate capture and collection of nail gun injury data, since nail gun injuries are so highly underreported, and directly measuring hours of exposure is difficult. A simple examination of workers’ compensation data, medical records, or employment records may not accurately depict the magnitude of the problem. Continued use of active surveillance, similar to Lipscomb’s various studies, [4, 6, 11] should be used to best capture nail gun injury data. A third area that would be interesting to research further would be the magnitude of nail gun injuries with the at-home, non-occupational nail gun user, and how effective strategies are in controlling their rate of injury. A final area for continued research includes non-unionized, small contractor, residential, or non-native populations in construction. There is very little data on these populations due to the structure of work, employee turnover, the unique occupational culture, and the research challenges that are present. The majority of those exposed are within these populations, so learning the true magnitude of their nail gun injury problem, along with the effectiveness of controls or interventions on these populations is extremely important.