Process safety incident investigation (29 CFR 1910.119(m))
Short answer
Covered employers must investigate every incident that resulted in, or could reasonably have resulted in, a catastrophic release of a highly hazardous chemical (29 CFR 1910.119(m)). Start as promptly as possible, no later than 48 hours after the incident. Use a team with someone who knows the process. Write a report, resolve the findings and keep it five years.
- Rule
- 29 CFR 1910.119(m), Incident investigation
- Trigger
- An incident that resulted in, or could reasonably have resulted in, a catastrophic release
- Start
- As promptly as possible, no later than 48 hours after the incident
- Team
- One person who knows the process, plus a contract employee if contractors were involved
- Report
- Incident and start dates, description, contributing factors, recommendations
- Retention
- 5 years
- Near miss
- Not in the rule text; only in nonmandatory Appendix C
Applies to: Employers with a process involving a highly hazardous chemical at or above its Appendix A threshold quantity · Employers with 10,000 pounds or more of a Category 1 flammable gas or a flammable liquid with a flashpoint below 100 °F in one location, subject to the exceptions · Chemical, food processing, water treatment, utility, laboratory and pharmaceutical production sites that exceed those thresholds
What does 1910.119(m) require?
Seven paragraphs cover which incidents to investigate through how long to keep the report.
| Paragraph | Requirement |
|---|---|
| (m)(1) | Investigate each incident that resulted in, or could reasonably have resulted in, a catastrophic release of a highly hazardous chemical in the workplace |
| (m)(2) | Start the investigation as promptly as possible, and no later than 48 hours after the incident |
| (m)(3) | Set up a team with at least one person who knows the process, and others with the right knowledge and experience. Include a contract employee if the incident involved contractor work. |
| (m)(4) | Write a report at the end. It must include at least the incident date, the date the investigation began, a description, contributing factors and recommendations. |
| (m)(5) | Have a system to promptly address and resolve findings and recommendations. Document the resolutions and corrective actions. |
| (m)(6) | Review the report with affected personnel whose tasks are relevant, including contract employees |
| (m)(7) | Keep investigation reports for five years |
The rule sets a deadline to start the investigation. It sets none to finish it.
Which employers are covered?
Employers with a covered process under 1910.119(a). A process is covered if it involves either of these.
- A chemical at or above its Appendix A threshold quantity. Examples are 10,000 pounds of anhydrous ammonia or 1,500 pounds of chlorine.
- 10,000 pounds or more of a Category 1 flammable gas or a flammable liquid with a flashpoint below 100 °F, on site in one location. Hydrocarbon fuels used solely as a workplace fuel are excepted. So are flammable liquids in atmospheric tanks kept below their normal boiling point.
The standard does not apply to retail facilities, oil or gas well drilling or servicing, or normally unoccupied remote facilities.
What about near misses?
The rule never uses the words 'near miss'. It uses a test: an incident that 'could reasonably have resulted' in a catastrophic release. OSHA's nonmandatory Appendix C notes that such events are sometimes called near misses.
A near miss that meets the test needs a full investigation, not a log entry. A catastrophic release is a major uncontrolled emission, fire or explosion involving one or more highly hazardous chemicals. It presents serious danger to employees in the workplace (1910.119(b)). Screen each event against that definition and write down the decision. See near-miss reporting and near miss.
Who must be on the investigation team?
The team needs at least one person who knows the process. OSHA's PSM directive (CPL 02-01-065, effective January 26, 2024) allows an operator or maintenance person who knows how the process works. It also allows a process engineer or operations supervisor who knows how it is designed to work. An hourly employee is not required. Knowledge and experience count, not pay.
Appendix C recommends a team from several fields, trained to interview witnesses, document facts and write reports. It says to focus on facts, not blame. If the incident involved contractor work, include a contract employee.
What happens after the report is written?
Findings and recommendations must be resolved promptly, and the resolution documented ((m)(5)). OSHA's directive says a recommendation is resolved when the employer adopts it or justifiably declines it.
- Declining a recommendation needs a written record based on adequate evidence. Valid grounds: material factual errors in the analysis, no need to protect employees, an alternative that protects enough, or infeasibility.
- Accepting one needs documentation of the actions and a written schedule. Finish as soon as possible and tell affected operating and maintenance staff.
- Then review the report with affected personnel, including contract employees, and keep it for five years.
Which events trigger an investigation?
These examples assume a covered process. The right call depends on the facts and your screening record.
| Scenario | Investigate under (m)? | Why |
|---|---|---|
| A fire starts in a covered process unit | Yes | A fire involving a highly hazardous chemical can be a catastrophic release. |
| Pressure goes past safe limits and damages a vessel, but nothing is released | Likely yes | It could reasonably have resulted in a catastrophic release. Document the reasoning. |
| A small pump seal leak is caught and contained within minutes | Screen and document | Decide if it could reasonably have become catastrophic. Keep the screening record. |
| A person slips on a plant stairway, with no process involvement | No | Not a process safety event. It may still be recordable under Part 1904. |
The same event can also be a Part 1904 case. If anyone is badly hurt, it is also a severe injury report. PSM adds the 48-hour start, the written report and the documented resolution.
How IncidentKit supports this requirement
| What the rule asks for | Where it lives in IncidentKit |
|---|---|
| Investigate each qualifying incident ((m)(1)) | Near misses are incident types with the same record, routing and review as injuries. A person makes and documents the screening decision. |
| Start the investigation within 48 hours ((m)(2)) | Immediate-priority incidents escalate after a window you set per facility. An unacknowledged event reaches the next owner. An investigation opens from the incident record. |
| Team with a person knowledgeable in the process ((m)(3)) | Investigations are assigned to named people. Photos, work orders and documents stay attached as evidence. |
| Write the report ((m)(4)) | Structured contributing factors and a five-whys chain. Lauren drafts them, and the investigator edits and signs. Every case gets a disposition. |
| Resolve and document recommendations ((m)(5)) | Corrective actions need an owner, due date and evidence. The incident closes only when actions are verified. Record the reason when a recommendation is declined. |
| Review with affected personnel and keep five years ((m)(6), (m)(7)) | The audit trail shows who approved what and when. The per-incident PDF and CSV export support the file. Plant packs are rolling out; the core workflow runs now. |
Product parts involved: Investigations and RCA, Corrective actions (CAPA), Incident reporting, Routing and escalation, Audit trail, Lauren, the AI assistant. Capabilities marked “rolling out” are being released in stages; see the changelog.
Frequently asked questions
When does the 48-hour clock start?
It runs from the incident, not from when you find out. Start as promptly as possible, and no later than 48 hours after the incident. Name the team early.
Is the investigation report due within 48 hours?
No. Only the start of the investigation has a 48-hour limit. The report is written at the end, and the rule sets no completion deadline.
Does a near miss need a PSM investigation?
Yes, if it meets the test: it could reasonably have resulted in a catastrophic release. OSHA's Appendix C notes such events are sometimes called near misses. Screen each event and document the decision.
Can we reject an investigation recommendation?
Yes, if you justify it in writing with adequate evidence. Grounds are material factual errors in the analysis, no need to protect your or your contractors' employees, an alternative that protects enough, or infeasibility.
How long must investigation reports be kept?
Five years. Paragraph (m)(7) requires you to keep incident investigation reports for five years.
Sources
- eCFR: 29 CFR 1910.119, Process safety management of highly hazardous chemicals (current through 2026-10-01)
- OSHA: 29 CFR 1910.119 regulation text, including nonmandatory Appendix C
- OSHA: Process Safety Management of Highly Hazardous Chemicals, directive CPL 02-01-065 (effective 2024-01-26)
- OSHA: Process safety management topic page
Reviewed against the sources above on Oct 5, 2026. Rules change: confirm current requirements with the issuing body or your counsel before relying on any summary.
Map this requirement to your records.
IncidentKit connects each rule to the incident, investigation and corrective action that satisfy it.