FactSheet
The Importance of Root Cause Analysis
During Incident Investigation
The Occupational Safety and Health Administration (OSHA) and the Environmental
Protection Agency (EPA) urge employers (owners and operators) to conduct a root
cause analysis following an incident or near miss at a facility.1 A root cause is a
fundamental, underlying, system-related reason why an incident occurred that
identifies one or more correctable system failures.2 By conducting a root cause
analysis and addressing root causes, an employer may be able to substantially or
completely prevent the same or a similar incident from recurring.
OSHA Process Safety Management
and EPA Risk Management Program
Requirements
Employers covered by OSHA’s Process Safety
Management (PSM) standard are required
to investigate incidents that resulted in, or
could reasonably have resulted in, catastrophic
releases of highly hazardous chemicals.3
Similarly, owners or operator s of facilities
regulated under EPA’s Risk Management
Program (RMP) regulations must conduc t
incident investigations.4
During an incident investigation, an employer
must determine which factors contributed to
the incident, and both OSHA and the EPA
encourage employers to go beyond the minimum
investigation required and conduc t a root
cause analysis . A root cause analysis allows an
employer to discover the u nderlying or systemic,
rather than the generalized or immediate, causes
of an incident. Correcting only an immediate
cause may eliminate a symptom of a problem,
but not the problem itself.
How to Conduct a Root Cause Analysis
A successful root cause analysis identifies all
root causes —there are often more than one.
Consider the following example: A worker slips
on a puddle of oil on the plant floor and falls.
A traditional investigation may find the cause
to be “oil spilled on the floor” with the remedy
limited to cleaning up the spill and instructing
the worker to be more careful.5 A root cause
analysis would reveal that the oil on the floor
was merely a symptom of a more basic, or
fundamental problem in the workplace.
An employer conduc ting a root cause analysis
to determine whether there are systemic reasons
for an incident should ask:
– Why was the oil on the floor in the first place?
– Were there changes in conditions, processes,
or the environment?
– What is the source of the oil?
– What tasks were under way when the oil
was spilled?
– Why did the oil remain on the floor?
– Why was it not cleaned up?
– How long had it been there?
– Was the spill reported?6
It is important to consider all possible “what,”
“why,” and “how” questions to discover the root
cause(s) of an incident.
In this case, a root cause analysis may have
revealed that the root cause of the spill was a
failure to have an effective mechanical integrity
program— that includes inspection and repair—
that would prevent or detect oil leaks. In contras t,
an analysis that focused only on the immediate
cause (failure to clean up the spill) would not have
prevented future incidents because there was no
system to prevent, identif y, and correct leaks.
Properly framing and conducting a root cause
investigation is important for a PSM or RMP-
related incident. Take, for example, an incident
involving an overfill and subsequent leak of
hydrocarbons from a relief valve system that
ignites and kills multiple workers. Prior to this
fatal incident, there were multiple flammable
releases from the relief valve sys tem, but none
ignited. The employer previously per formed
