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Course 800 - Introduction to Construction Safety Management

Safety guides and audits to make your job as a safety professional easier

Hazard Prevention and Control

Controlling Exposure - The Hierarchy of Controls

Controlling exposures to worksite hazards is the fundamental method of protecting workers on a construction site. Traditionally, the widely-accepted hierarchy of controls has been used as a means of determining how to implement feasible and effective controls.

Image of Hierarchy of Controls in Construction
The Hierarchy of Controls

ANSI/AIHA Z10 discusses six control strategies:

  1. Elimination
  2. Substitution
  3. Engineering controls
  4. Warnings
  5. Administrative controls
  6. Personal Protective Equipment

The idea behind this hierarchy is that the control methods at the top of the list are potentially more effective and protective than those at the bottom. Following the hierarchy normally leads to the implementation of inherently safer systems. The risk of illness or injury should be substantially reduced. Let’s take a closer look at each of the control measures.

Check out this short audio clip by Dan Clark of the talks about the Hierarchy of Controls.


The best control measure to control a hazard is to eliminate it. If you don’t have the hazard, you won’t get injured. While elimination is the most effective at reducing hazards, it also tend to be the most difficult to implement in an existing process.

If the construction project is still at the design or development stage, elimination and substitution of hazards may be inexpensive and simple to implement. For an existing process, major changes in equipment and procedures may be required to eliminate or substitute for a hazard.


The next best control measure is to substitute something else in its place that would be non-hazardous or less hazardous to workers. For example, substituting a toxic chemical with a non-toxic (or less toxic) one.

Engineering Controls

Engineering controls are used to remove a hazard or place a barrier between the worker and the hazard. Well-designed engineering controls can be highly effective in protecting workers and will typically be independent of worker interactions to provide this high level of protection.

The initial cost of engineering controls can be higher than the cost of administrative controls or personal protective equipment, but over the longer term, operating costs are frequently lower, and in some instances, can provide a cost savings in other areas of the process. Engineering controls should be designed to make it difficult for employees to defeat the controls.

Engineering controls include methods such as using noise dampening technology to reduce noise levels; enclosing a chemical process in a Plexiglas "glove box"; using mechanical lifting devices; or using local exhaust ventilation that captures and carries away the contaminants before they can get in the breathing zone of workers.

Warnings and Administrative Controls

If engineering controls cannot be implemented, or cannot be implemented right away, administrative controls should be considered. These methods for protecting workers have also proven to be less effective than other measures, requiring significant effort by the affected workers. Administrative controls work only so long as employee behavior conforms to standards.

Safe Procedures and Training

Administrative controls involve changes in workplace policies and procedures. They can include such things as:

  • warning alarms
  • labeling systems
  • reducing the time workers are exposed to a hazard
  • training

For example, workers could be rotated in and out of a hot area rather than having to spend eight hours per day in the heat. Back-up alarms on trucks that are backing up are an example of effective warning systems. However, warning signs used instead of correcting a hazard that can and should be corrected are not acceptable forms of hazard control.

Personal Protective Equipment

PPE is the last resort and least effective means of controlling exposure to hazards because of the high potential for damage to render PPE ineffective. Again, the success of this control measure depends not only on the quality of the PPE, but also the quality of human behavior.

Fall protection harnesses and equipment are examples of PPE.

PPE should be used only while other more effective controls are being developed or installed, or if there are no other more effective ways to control the hazard.

This is because:

  • The hazard is not eliminated or changed.
  • If the equipment is inadequate or fails, the worker is not protected.
  • No personal protective equipment is fool-proof (for example, respirators leak).
  • Personal protective equipment is often uncomfortable and can place an additional physical burden on a worker.
  • Personal protective equipment can actually create hazards. For example, the use of respirators for long periods of time can put a strain on the heart and lungs.

While there are some jobs, such as removing asbestos, where wearing adequate personal protective equipment is absolutely essential, there are many jobs where employers hand out personal protective equipment when in fact they should be using more effective hazard control methods.

Other Methods to Prevent and Control Hazards

Let’s take a look at some of the programs and processes that will help the company prevent and control typical hazards on a construction worksite.

Worksite Inspections

As mentioned earlier, your company should conduct daily worksite inspections. Hazards should be documented, reviewed, and corrections should be made in a timely manner. More detailed, written inspections should be conducted by a designated person on a weekly or monthly basis.

Your company's Safety Coordinator or other designated safety person should tour each job site and observe potential safety/health hazards and unsafe behaviors, and develop a plan for implementing corrective actions and system improvements to safeguard workers, which may include the following:

  1. removing the hazard
  2. guarding against the hazard as required by OSHA
  3. providing personal protective equipment and enforcing its use
  4. training workers in safe work practices
  5. coordinating protection of workers through other contractors

A record of all safety inspections and correctional steps should be kept.

Analyze Past Performance

All accidents in your workplace resulting in injury or property damage should be investigated.


To get the best picture of past safety performance on worksites, gather and analyze data on all previous injury accidents, accident resulting in property damage, and near-miss incidents.

By using the information gained through analysis of incident/accident investigations occurring on previous projects, a similar, or perhaps more disastrous, accident may be prevented.

Control of Hazardous Energy

The control of hazardous energy through lockout/tagout procedures assures that employees are protected from unintended machine motion or unintended release of energy which could cause injury. This includes electricity, water, steam, hydraulic, gravity, and many other sources of stored energy.

All sources of energy must be shut off, de-energized at the source, and locked-out prior to you or any other employee beginning work around or on the potential hazard.

Confined Space Entry

Analyze the project for the potential for confined spaces. Workers should not enter confined spaces without proper training and management authorization.

A confined space is defined as the following4:

Confined Space
  1. a space that is not designed for continuous employee occupancy,
  2. is large enough and so configured that a person can bodily enter into and perform assigned work
  3. has limited or restricted means for entry of exit

Confined spaces that may have a hazardous atmosphere require special precautions. Hazardous atmospheres are those that may expose employees to the risk of death, incapacitation, and impairment of ability to self-rescue caused by:

  • flammable atmospheres - gases or oxygen level above 23.5%
  • airborne combustible dust or fibers - sugar, plastic, wood, etc.
  • oxygen-deficient atmosphere - concentration below 19.5
  • toxic gases, vapors, or fumes - carbon monoxide, hydrogen sulfide etc.
  • high concentration of inert gases - nitrogen, helium, radon, etc.
fall protection
Is this fall protection system sufficient?

Analyze Fall Hazards

Each year, falls consistently account for the greatest number of fatalities in the construction industry5. A number of factors are often involved in falls, including:

  • unstable working surfaces
  • misuse or failure to use fall protection equipment
  • human error

Studies have shown that using guardrails, fall arrest systems, safety nets, covers and restraint systems can prevent many deaths and injuries from falls.

Analyze the project to determine if you will be using:

  • aerial lifts or elevated platforms to provide safer elevated working surfaces
  • guardrail systems with toeboards and warning lines or install control line systems to protect workers near the edges of floors, roofs, and floor holes; and/or
  • safety net systems or personal fall arrest systems (body harnesses)
A cave-in occurred after inspector told worker to get out of trench.

Analyze for Excavation Hazards

The primary hazard of trenching and excavation is employee injury from collapse. A competent person must inspect and analyze the excavation site on a daily basis and as frequently as necessary as work progresses to make sure that hazards are eliminated before workers are allowed to enter the trench. Soil analysis is important in order to determine appropriate sloping, benching, and shoring.

Additional hazards include:

  • working with heavy machinery
  • manual handling of materials
  • working in proximity to traffic
  • electrical hazards from overhead and underground power-lines
  • hazardous atmospheres
  • underground utilities, such as natural gas.

For more information on excavation safety take OSHAcademy Course 802, Trench and Excavation Safety.

Analyze for Hazardous Chemicals

Analyze the project for the potential for hazardous chemicals requiring a Hazard Communications Program (HCP) to ensure all workers know about the chemicals that they work with and work around. The HCP involves the following elements.

  1. written hazard communication program
  2. training on the chemicals your company uses
  3. labeling: using properly labeled containers
  4. Safety Data Sheets (SDS): SDSs must be readily available onsite. Workers must know where to find SDSs and be able to read and properly utilize an SDS.
  5. Posting signs to inform employees of the location of SDSs and when new chemicals are brought on the job site.
  6. Informing other contractors: If using chemicals around other contractors, it is your responsibility to inform the other contractors of the hazards involved. Every effort must be made to keep other contractors safe from the chemicals in use. Typically, the general contractor onsite will need to coordinate all chemical use of all contractors to maintain a safe workplace

Note: Your written Hazard Communication program should outline the specific details of the elements listed above.

Analyze Electrical Hazards

Electrical Safety - Crane Accident.

Electricity has become essential to modern life. Perhaps because it is such a familiar part of our surroundings, it often is not treated with the respect it deserves. Safety and health programs must address electrical incidents and the variety of ways electricity becomes a hazard. In general, OSHA requires that employees not work near any part of an electrical power circuit unless protected. The following hazards are the most frequent cause of electrical injuries See 29 CFR 1926.416(a)(1):

  • Contact with Power Lines - When using heavy equipment, stay at least 10 feet away from overhead powerlines
  • Lack of Ground-fault Protection - Use GFCIs
  • Path to Ground Missing or Discontinuous - Ground power supplies, circuits, and equipment
  • Equipment Not Used in Manner Prescribed - Use according to manufacturer's instructions
  • Improper Use of Extension and Flexible Cords - Use only factory-assembled, 3-wire extension cords

Deaths Due to Improper Use of Extension and Flexible Cords

A worker received a fatal shock when he was cutting drywall with a metal casing router. The router's 3-wire power cord was spliced to a 2-wire cord and plug set which was not rated for hard service. A fault occurred, and with no grounding and no GFCI protection, the worker was electrocuted.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following is the fundamental method of protecting workers on a construction site?

2. Which hazard control strategy is the most effective at reducing hazards, yet also tends to be the most difficult to implement in an existing process?

3. Engineering controls should be designed to make it _____ for employees to defeat the controls.

4. As a hazard control measure, _____ is the last resort and least effective means of controlling exposure to hazards because of the high potential for damage to render it ineffective.

5. Which of the following consistently accounts for the greatest number of fatalities in the construction industry?

Have a great day!

Important! You will receive an "error" message unless all questions are answered.