CIMAH Regulations Malaysia: Major Industrial Accident Hazards Requirements & Compliance

Malaysia has over 384 registered Major Hazard Installations as of 2021. That number has grown 400% since CIMAH took effect in 1996. If your facility stores, processes, or handles hazardous chemicals above certain threshold quantities, you fall under some of the strictest safety regulations in Malaysian law.

This guide breaks down every CIMAH requirement: how to determine if you're classified as MHI or NMHI, what threshold quantities trigger compliance, what goes into a safety report, and how to avoid penalties that now reach RM500,000 under OSHA 1994 (Amendment 2022).

This guide covers:

• What CIMAH 1996 regulates and who it applies to
• MHI vs NMHI classification criteria
• Schedule 2 threshold quantities for key chemicals
• Safety report structure (Parts A through D)
• Emergency Response Plan (ERP) requirements
• Competent Person (OKMH) requirements
• Penalties and enforcement under OSHA 1994
• Insurance implications for major hazard facilities

Disclaimer: This article provides general guidance based on the Occupational Safety and Health (Control of Industrial Major Accident Hazards) Regulations 1996 and official DOSH information as of February 2026. Regulations may be amended. Always verify current requirements with DOSH or qualified professionals before making compliance decisions.

What Are the CIMAH Regulations?

The Control of Industrial Major Accident Hazards (CIMAH) Regulations 1996 is subsidiary legislation under OSHA 1994. It regulates facilities that store, produce, process, handle, use, or dispose of hazardous substances that are toxic, flammable, explosive, or oxidising in nature. Malaysia adopted this framework following Britain's 1984 implementation of the European Seveso Directive.

DOSH enforces CIMAH through the Major Hazard Division. The regulations aim to prevent major industrial accidents and limit their consequences to people, property, and the environment. Every facility that handles listed chemicals above 10% of the threshold quantity has some level of compliance obligation.

Aspect	Details
Full Citation	Occupational Safety and Health (Control of Industrial Major Accident Hazards) Regulations 1996
Parent Act	Occupational Safety and Health Act 1994 (Act 514)
Effective Date	February 1996
Enforcement Agency	Department of Occupational Safety and Health (DOSH), Major Hazard Division
Registered MHIs (2021)	384 facilities nationwide
Exemptions	Nuclear installations, armed forces, transport of hazardous substances by vehicle/vessel, facilities at ≤10% threshold quantity

Who Must Comply: MHI vs NMHI Classification

CIMAH classifies facilities into two tiers based on the quantity of hazardous substances present relative to the Threshold Quantity (TQ) listed in Schedule 2. Your classification determines the scope of your compliance obligations. Get this wrong and you either over-invest in unnecessary documentation or face enforcement action for under-compliance.

Classification	Chemical Quantity	Key Obligations
Major Hazard Installation (MHI)	Quantity ≥ Threshold Quantity (TQ)	Full safety report, on-site ERP, public information, notification to DOSH and local authority
Non-Major Hazard Installation (NMHI)	10% TQ < Quantity < TQ	Demonstrate safe operation, submit simplified ERP
Exempt	Quantity ≤ 10% of TQ	Not subject to CIMAH (but still subject to general OSHA 1994 duties)

For facilities storing multiple hazardous substances, you must calculate the aggregate using the summation rule. Add together the ratio of each substance's quantity to its threshold quantity. If the sum equals or exceeds 1.0, you're classified as MHI.

MHI Compliance Requirements

If classified as MHI, your obligations are extensive. You must engage a DOSH-registered Competent Person (OKMH), prepare a full safety report, and submit it at least 3 months before introducing hazardous substances on-site.

MHI Requirement	Details	Frequency
Notification to DOSH	Notify Director General of industrial activity	Before commencement; upon changes
Safety Report (Report on Industrial Activity)	Full report per Schedule 6 requirements	Every 3 years or upon major modification
On-Site Emergency Response Plan	Detailed plan covering all major accident scenarios	Every 3 years; tested regularly
Information to Public	Disclose hazards, warnings, and protective actions to surrounding community	Ongoing; updated with each report cycle
Inform Local Authority	Help local authority prepare off-site ERP	Ongoing
Major Accident Notification	Report any major accident to DOSH immediately	Within prescribed time upon occurrence
Competent Person (OKMH)	DOSH-registered person must prepare all reports	Required for every submission

NMHI Compliance Requirements

NMHIs have lighter obligations but still can't ignore CIMAH. You must demonstrate your operations are safe and submit an emergency response plan. Many facilities wrongly assume they're exempt when they actually fall into the NMHI category.

Schedule 1: Hazard Categories and Classification

Schedule 1 defines four broad hazard categories used to classify substances even if they don't appear by name in Schedule 2. If your chemical falls under these generic criteria, CIMAH applies regardless of whether it's specifically listed.

Category	Classification Criteria	Generic Threshold Quantity
Very Toxic Substances	LD50 (oral) ≤25 mg/kg or LC50 (inhalation) ≤0.5 mg/L (4hr)	5 tonnes
Toxic Substances	LD50 (oral) 25-200 mg/kg or LC50 (inhalation) 0.5-2 mg/L (4hr)	10 tonnes
Highly Flammable	Flash point <21°C; flammable gases with boiling point ≤20°C	10,000 tonnes (liquids); varies for gases
Explosive/Oxidising	As classified under Schedule 2 groups	Per Schedule 2 specific entries

Schedule 2: Threshold Quantities for Named Substances

Schedule 2 is the core reference for CIMAH compliance. It lists specific hazardous substances grouped by hazard type, each with a defined threshold quantity in tonnes. If your facility holds any of these chemicals at or above the listed quantity, you're an MHI. Between 10% and 100% of the threshold quantity, you're an NMHI.

Group 1: Highly Toxic Substances

Substance	Threshold Quantity	Common Industrial Use
Methyl isocyanate	150 kg	Pesticide manufacturing
Phosgene	750 kg	Chemical intermediary, plastics
Hydrazine	100 kg	Boiler water treatment, rocket fuel
Fluoroacetic acid	1 kg	Rodenticide

Group 2: Toxic Substances

Substance	Threshold Quantity (tonnes)	Common Industrial Use in Malaysia
Chlorine	10	Water treatment, PVC production
Ammonia	100	Refrigeration, fertiliser plants
Hydrogen cyanide	20	Electroplating, gold extraction
Hydrogen fluoride	50	Semiconductor etching, petroleum refining
Hydrogen sulfide	50	Oil and gas, paper manufacturing
Acrylonitrile	20	Plastics, synthetic fibres
Formaldehyde (>90%)	20	Plywood/MDF adhesives, resins
Sulfur dioxide	20	Palm oil refining, sulphuric acid production
Bromine	10	Flame retardants, pharmaceuticals
Toluene di-isocyanate (TDI)	100	Polyurethane foam manufacturing
Carbon disulfide	200	Rayon production, rubber vulcanisation

Group 3: Highly Reactive Substances

Substance	Threshold Quantity (tonnes)	Common Industrial Use
Ethylene oxide	5	Sterilisation, petrochemicals
Hydrogen	10	Petroleum refining, semiconductor
Acetylene	50	Welding, chemical synthesis
Propylene oxide	50	Polyol production, propylene glycol
Oxygen (liquid)	500	Steel manufacturing, medical
Ammonium nitrate (bulk)	1,000	Explosives, fertiliser
Ammonium nitrate (fertiliser grade)	2,500	Agriculture

Group 4: Explosive Substances

Substance	Threshold Quantity (tonnes)
Nitroglycerin	10
Diethylene glycol dinitrate	10
2,4,6-Trinitrotoluene (TNT)	50
Lead azide	50

If your substance isn't listed in Schedule 2, check the generic criteria in Schedule 1. A chemical classified as "very toxic" by its LD50 value triggers CIMAH at 5 tonnes even without a specific listing.

How to Determine Your CIMAH Classification

Start by inventorying every hazardous substance on your premises. Include raw materials, intermediates, finished products, and waste storage. Don't forget maintenance chemicals and fuel reserves.

Step	Action	What to Check
1	List all hazardous substances on-site	Raw materials, intermediates, products, waste, fuel, maintenance chemicals
2	Determine maximum quantity present at any one time	Storage tanks, process vessels, warehouses, drum storage areas
3	Check against Schedule 2 named substances	Match CAS number, not just common name
4	For unlisted substances, apply Schedule 1 generic criteria	LD50, LC50, flash point, boiling point from Safety Data Sheet
5	For multiple substances, apply summation rule	Sum of (quantity/TQ) for each substance; ≥1.0 = MHI
6	Classify as MHI, NMHI, or exempt	≥TQ = MHI; 10%-100% TQ = NMHI; <10% TQ = exempt

Summation Rule Example

A factory stores 5 tonnes of chlorine (TQ: 10 tonnes) and 60 tonnes of ammonia (TQ: 100 tonnes). The calculation: (5/10) + (60/100) = 0.5 + 0.6 = 1.1. Because 1.1 ≥ 1.0, this facility is classified as MHI, even though neither chemical individually exceeds its threshold quantity.

Safety Report Requirements (Report on Industrial Activity)

The CIMAH safety report is a comprehensive document that demonstrates your facility has identified all major accident scenarios and implemented adequate controls. It must be prepared by a DOSH-registered Competent Person (Orang Kompeten Majlis Hazard, or OKMH) and follows the structure prescribed in Schedule 6.

Report Structure: Parts A Through D

Part	Content	Key Deliverables
Part A: Hazardous Substances	Full inventory of all hazardous chemicals on-site	Chemical names, quantities, purity levels, impurities, storage conditions, Safety Data Sheets
Part B: Installation Information	Site layout and surrounding area details	Site maps, population data within risk zones, proximity to hospitals/schools/residential areas, meteorological data, emergency services access
Part C: Management System	Safety management and control procedures	Organisational structure, training programmes, maintenance procedures, permit-to-work systems, management of change (MOC) procedures
Part D: Consequence Modelling & Risk Quantification	Major accident scenarios and risk assessment	Process Flow Diagrams (PFDs), HAZOP studies, consequence modelling, LSIR contours, risk to surrounding population

For updated reports, you must also include an Executive Summary and a Summary of Findings documenting changes since the last submission. DOSH's 2023 Guidance on Preparation and Updating of Report on Industrial Activity (2nd Edition) provides detailed requirements for each section.

Submission Timeline

Scenario	Submission Deadline
New facility (before introducing hazardous substances)	At least 3 months before commencement
Routine update	Every 3 years from last approval
Major modification to plant or process	Before implementing the modification
After a major accident	As directed by DOSH
Change in hazardous substance quantities exceeding current classification	Before the change takes effect

Emergency Response Plan (ERP) Requirements

Every MHI must prepare and maintain an on-site Emergency Response Plan. This isn't a generic fire evacuation plan. It must address specific major accident scenarios identified in Part D of your safety report, including toxic releases, explosions, and large fires.

Your ERP must also coordinate with the local authority's off-site emergency plan. You're required to help the local authority prepare their response to an incident at your facility. For more on general ERP frameworks, see our guide on emergency response plans in Malaysia.

ERP Component	Requirements
Accident scenarios	All credible major accident scenarios from Part D of the safety report
Command structure	Clear incident commander, deputy, and team roles with contact details
Alarm and notification	Alarm systems, notification cascade to DOSH, BOMBA, police, hospital, local authority
Evacuation procedures	On-site evacuation routes, muster points, headcount procedures
Emergency equipment	Fire fighting, gas detection, SCBA, decontamination facilities, medical first aid
External coordination	Interface with off-site ERP, mutual aid agreements with neighbouring facilities
Training and drills	Regular training, tabletop exercises, full-scale drills with external agencies
Review and update	Updated every 3 years alongside the safety report, or after any activation

Competent Person (OKMH) Requirements

You can't prepare CIMAH reports in-house without a qualified person. The regulations require a DOSH-registered Competent Person (OKMH) to prepare all safety reports and related submissions. The OKMH certificate must accompany every report submitted to DOSH.

OKMH registration requires demonstrated competence in process safety, consequence modelling, and risk quantification. DOSH maintains a registry of approved OKMHs that facilities can engage. The cost of hiring an OKMH varies significantly depending on facility complexity, but budget between RM50,000 to RM200,000 for a full CIMAH report preparation.

Industries Most Affected by CIMAH in Malaysia

Malaysia's industrial landscape includes several sectors where CIMAH compliance is common. Petrochemical facilities along the east coast, semiconductor fabs in Penang and Kulim, palm oil refineries, and LPG storage terminals all regularly handle substances above threshold quantities.

Industry	Common CIMAH Substances	Typical Classification
Petrochemical / Oil & Gas	Hydrogen, LPG, ethylene oxide, ammonia, hydrogen sulfide	MHI
Semiconductor / Electronics	Hydrogen fluoride, hydrogen, arsine, phosphine	MHI or NMHI
Water Treatment	Chlorine, ammonia	MHI (large plants) or NMHI
Palm Oil Refining	Hydrogen, sulfur dioxide, hexane	NMHI to MHI
Chemical Manufacturing	Various per Schedule 2	MHI
LPG Storage & Distribution	Liquefied petroleum gas	MHI (>50 tonnes)
Cold Storage / Refrigeration	Ammonia	NMHI (10-100 tonnes) to MHI
Fertiliser Manufacturing	Ammonia, ammonium nitrate	MHI

CIMAH vs USECHH: Understanding the Difference

Plant managers sometimes confuse CIMAH with USECHH (Use and Standards of Exposure of Chemicals Hazardous to Health). They're different regulations with different scopes. CIMAH focuses on preventing major industrial accidents involving large quantities of hazardous substances. USECHH focuses on occupational health exposure during routine handling of chemicals, including the Chemical Health Risk Assessment (CHRA).

Aspect	CIMAH 1996	USECHH 2000
Focus	Major industrial accidents (explosions, toxic releases, large fires)	Occupational health exposure during routine work
Trigger	Quantity of hazardous substance vs threshold quantity	Any use of chemicals hazardous to health
Key Assessment	Consequence modelling, risk quantification (QRA)	Chemical Health Risk Assessment (CHRA)
Assessor	DOSH-registered OKMH (Competent Person)	DOSH-registered Chemical Health Risk Assessor (CHRA Assessor)
Scope	Facility-wide, includes off-site consequences	Worker exposure at specific work areas
Update Cycle	Every 3 years	Every 5 years or upon process change

Many MHI facilities need both CIMAH compliance and CHRA assessments. They're not interchangeable.

CIMAH and HIRARC: How They Connect

Your facility's HIRARC assessment identifies workplace hazards at the operational level. CIMAH goes further by requiring quantitative risk assessment (QRA) for major accident scenarios. Think of HIRARC as addressing day-to-day operational risks, while CIMAH addresses catastrophic, low-probability events with major consequences.

Both are required. A HIRARC might identify "chemical splash during transfer" as a hazard. CIMAH would assess "catastrophic failure of 100-tonne ammonia storage tank" and model the toxic gas dispersion plume across surrounding residential areas.

Penalties for Non-Compliance

The CIMAH Regulations 1996 specify penalties under Regulation 21. But since CIMAH is subsidiary legislation under OSHA 1994, general duty failures can attract the higher penalties introduced by the OSHA 1994 (Amendment 2022), Act A1648, effective 1 June 2024.

Offence	Penalty (CIMAH Reg 21)	Penalty (OSHA 1994 General Duty, post-Amendment 2022)
Manufacturer non-compliance	Fine up to RM50,000 or imprisonment up to 2 years, or both	Fine up to RM500,000 or imprisonment up to 2 years, or both
Employee non-compliance	Fine up to RM1,000 or imprisonment up to 3 months, or both	Fine up to RM50,000 (Section 26 OSHA 1994)
Failure to ensure safety (Section 15 OSHA)	N/A (parent Act applies)	Fine up to RM500,000 or imprisonment up to 2 years, or both
Failure as designer/manufacturer of substance (Section 21)	N/A (parent Act applies)	Fine up to RM200,000

The practical reality: DOSH can charge under both CIMAH regulations and the parent OSHA 1994 Act simultaneously. A major accident at an unregistered MHI could result in multiple charges with cumulative penalties. Beyond fines, a serious incident can trigger criminal prosecution under the Penal Code if negligence caused death.

Insurance Implications for CIMAH Facilities

Major hazard installations face insurance requirements that go well beyond standard factory coverage. The scale of potential losses at CIMAH-regulated facilities makes proper insurance structuring essential.

Insurance Type	Why CIMAH Facilities Need It	Key Considerations
Industrial All Risks (IAR)	Covers property damage from fire, explosion, chemical reaction	Sum insured must reflect full replacement cost including specialist equipment; standard fire policy may exclude explosion
Business Interruption (BI)	Major accidents shut down operations for months or years	Indemnity period must be long enough (24-36 months); include supplier/customer extension for supply chain exposure
CGL Insurance	Third-party bodily injury and property damage from toxic releases, explosions	Standard CGL may exclude pollution; need sudden and accidental pollution coverage at minimum; consider environmental impairment liability
Workmen Compensation	Employee injuries from chemical exposure, fire, explosion	Ensure adequate limits for multiple simultaneous casualties; consider top-up coverage above statutory minimum
Machinery Breakdown	Process equipment failure can trigger CIMAH-scale incidents	Include pressure vessels, reactors, heat exchangers; coordinate deductibles with IAR policy

Insurers often request sight of your CIMAH safety report when underwriting major hazard facilities. A well-documented safety report with current risk assessments can improve your risk profile and potentially reduce premiums. Conversely, operating without proper CIMAH compliance may void certain policy conditions.

Common CIMAH Compliance Mistakes

Mistake	Consequence	How to Avoid
Not applying the summation rule for multiple chemicals	Under-classifying as NMHI when you're actually MHI	Calculate aggregate ratio for all hazardous substances on-site
Forgetting maintenance chemicals and fuel storage	Incomplete chemical inventory leads to wrong classification	Audit entire premises including workshops, generator areas, laboratories
Using an unregistered consultant for the safety report	Report rejected by DOSH; wasted time and money	Verify OKMH registration with DOSH before engaging
Missing the 3-year update cycle	Operating with expired report; enforcement action	Set calendar reminders 6 months before expiry to engage OKMH
Not updating after process modifications	Safety report no longer reflects actual risks	Integrate CIMAH review into your Management of Change (MOC) procedure
ERP that hasn't been tested	Plan fails during actual emergency; regulatory non-compliance	Conduct annual drills; full-scale exercise with external agencies at least once per 3-year cycle
No coordination with local authority on off-site ERP	Regulatory breach; poor emergency response if incident occurs	Initiate contact with local authority; provide facility information proactively

CIMAH Compliance Self-Assessment Checklist

Item	Yes/No
Complete inventory of all hazardous substances on-site with maximum quantities
Classification determined (MHI/NMHI/exempt) using summation rule where applicable
DOSH notified of industrial activity
DOSH-registered OKMH engaged for safety report preparation
Safety report (Parts A-D) current and approved by DOSH
On-site ERP prepared, documented, and communicated to all staff
ERP drills conducted and documented
Local authority informed and off-site ERP coordination in place
Public information provided to surrounding community
Management of Change (MOC) procedure includes CIMAH review trigger
3-year renewal timeline tracked with advance planning
Insurance coverage reviewed against CIMAH-scale loss scenarios

FAQ

What does CIMAH stand for in Malaysia?

CIMAH stands for Control of Industrial Major Accident Hazards. It refers to the Occupational Safety and Health (Control of Industrial Major Accident Hazards) Regulations 1996, subsidiary legislation under OSHA 1994 enforced by DOSH.

Who needs to comply with CIMAH regulations?

Any facility that stores, processes, handles, or disposes of hazardous substances above 10% of the threshold quantity listed in Schedule 2. This includes chemical plants, petrochemical facilities, LPG terminals, semiconductor fabs, water treatment plants, and cold storage facilities using ammonia refrigeration. Facilities at or above the full threshold quantity are classified as Major Hazard Installations (MHI) with the most extensive obligations.

How much does a CIMAH safety report cost?

A full CIMAH safety report typically costs between RM50,000 to RM200,000 depending on facility complexity, number of hazardous substances, and the scope of consequence modelling required. Simple single-substance installations cost less. Complex petrochemical facilities with multiple process units cost significantly more. This must be prepared by a DOSH-registered OKMH.

How often must the CIMAH safety report be updated?

Every 3 years from the date of last approval, or earlier if there are major modifications to plant, process, or chemical inventory. Changes that alter your CIMAH classification or introduce new major accident scenarios trigger an immediate update requirement.

What is the difference between MHI and NMHI?

MHI (Major Hazard Installation) applies when your hazardous substance quantity meets or exceeds the threshold quantity. MHI must submit a full safety report, on-site ERP, and public information. NMHI (Non-Major Hazard Installation) applies when quantities are between 10% and 100% of the threshold. NMHI must demonstrate safe operation and submit a simplified ERP.

Can CIMAH and USECHH apply to the same facility?

Yes. CIMAH addresses major accident prevention for large-quantity storage, while USECHH covers routine occupational exposure to chemicals hazardous to health. A petrochemical plant storing 200 tonnes of ammonia (CIMAH) would also need CHRA assessments for workers handling chemicals daily (USECHH). Both regulations are enforced by DOSH.

What happens if a major accident occurs at an unregistered facility?

Operating as an unregistered MHI is a serious offence. If a major accident occurs, you face penalties under both CIMAH regulations and OSHA 1994 (up to RM500,000 per charge after the 2022 Amendment). Criminal prosecution under the Penal Code is possible if negligence caused death or injury. Your insurance claims may also be jeopardised if non-compliance is discovered.

Does CIMAH apply to LPG storage?

Yes. LPG is a flammable gas regulated under CIMAH. Facilities storing 50 tonnes or more of LPG are classified as MHI. Between 5 and 50 tonnes, you're an NMHI. Below 5 tonnes (10% of TQ), you're exempt from CIMAH but still subject to general OSHA 1994 duties and other applicable regulations.

What is an OKMH and how do I find one?

OKMH (Orang Kompeten Majlis Hazard) is a DOSH-registered Competent Person qualified to prepare CIMAH safety reports. DOSH maintains a registry of approved OKMHs. You can contact DOSH's Major Hazard Division for the current list. Ensure your OKMH's registration is valid before engagement, as an expired registration means your report won't be accepted.

How does CIMAH compliance affect my insurance premiums?

Proper CIMAH compliance demonstrates risk management maturity to insurers. A current safety report with well-documented risk controls can improve your underwriting profile. Insurers underwriting IAR and CGL policies for major hazard facilities often request the safety report as part of their assessment. Non-compliance may result in coverage restrictions or policy conditions that limit claims.

Foundation Conclusion

CIMAH compliance isn't optional for facilities handling hazardous chemicals above threshold quantities. With 384 registered MHIs in Malaysia and growing, DOSH's Major Hazard Division actively monitors compliance. The 2022 OSHA Amendment's tenfold penalty increase signals that enforcement will only get stricter.

Major hazard installations need insurance programmes designed for catastrophic loss scenarios. Standard factory policies don't cover the scale of damage a major industrial accident can cause. IAR, business interruption, and CGL with pollution coverage form the minimum protection for CIMAH-regulated facilities.

Talk to our risk specialists about insurance for major hazard installations