1.4. Unsafe Act and Unsafe Conditions

Accidents are occurrences that are:

Accident Theory

The System Theory of Accident Causation proposes that work is a system composed a group of regularly interacting and interrelated components such as people, equipment/machineries/tools, materials and environment as shown in the figure in Accident Theory.

The likelihood for an accident to occur is dependent on how these components interact. Each component or a combination of these components are considered source of hazard that can either cause injury or illness to the worker after being exposed.

Example: An inexperienced worker who temporarily replaces a competent operator of a machine has increased probability of figuring an accident.

1.Fall to:

        > lower level

        > same level

2.  Caught:

        > on

        > in

        > in between

3. Struck:

        > against

        > by

4. Contact with:

        > chemicals

        > electricity

        > heat/cold

        > radiation

5. Rubbed or abraded by:

        > friction

        > pressure

        > vibration

Causes of Accidents

Unsafe Acts

American National Standards Institute


Factors Contributing to Unsafe Acts

• Improper Attitude

• Physical Limitations

• Lack of Knowledge or Skills

Unsafe Conditions

American National Standards Institute


●OSH is an issue that is rooted on something beyond Unsafe Acts and Unsafe Conditions. “Behind every unsafe condition, there is a management that allowed that hazard to exist and behind every unsafe behavior, there is a management system and organizational culture that leads people to act unsafely” (Dan Petersen, as quoted by Steve Minter).

●That leads to the Multiple Causation Theory of Accident arguing that a single accident has multiple causes. The theory considers unsafe acts and unsafe conditions together with human errors as the immediate causes of accidents. And behind those immediate causes, there is system failure and personal beliefs as root causes (Hartshorn).

Multiple Causation Theory of Accident