HSE OCM8 Storing Chemicals General Ventilation – Offshore

Guidance on Providing Safe General Ventilation for Offshore Chemical Storage Areas

LEVCentral Expert Commentary

Although written specifically for the offshore oil and gas industry, HSE OCM8 – Storing Chemicals: General Ventilation contains principles that apply equally to many onshore industrial workplaces where hazardous chemicals are stored.

The guidance forms part of HSE’s Offshore COSHH Essentials (OCE) series and focuses on the use of general ventilation to prevent the accumulation of hazardous vapours within chemical storage areas. Unlike many COSHH guidance sheets that concentrate on Local Exhaust Ventilation (LEV), OCM8 recognises that for the storage of sealed chemical containers, the primary engineering control is often well-designed dilution ventilation, supported by good storage practices and suitable management controls.

The document explains how natural or mechanical ventilation can reduce the build-up of hazardous vapours arising from minor leaks, spills or routine handling of chemicals. It also emphasises the importance of segregation, appropriate storage arrangements, housekeeping and emergency planning.

For LEV professionals, OCM8 provides an important reminder that LEV is not always the most appropriate engineering control. Where contaminants are not generated from a defined point source, well-designed general ventilation may provide the most practical and proportionate means of controlling exposure.

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View Original HSE Guidance

Key Learning Points

The guidance covers:

Safe storage of hazardous chemicals.
The purpose of general ventilation.
Natural versus mechanical ventilation.
Preventing the build-up of hazardous vapours.
Safe handling of chemical containers.
Spill prevention and management.
Good housekeeping.
Segregation of incompatible substances.
Information, instruction and training.
Maintenance of ventilation systems.
COSHH assessment and management responsibilities.

Source Document Information

Organisation: Health and Safety Executive (HSE)

Document: OCM8 – Storing Chemicals: General Ventilation

Series: Offshore COSHH Essentials (OCE)

Document Type: COSHH Essentials Guidance Sheet

Primary Topics: Chemical Storage, General Ventilation, COSHH, Offshore Safety, Occupational Hygiene

Audience: Offshore Operators, Chemical Store Managers, Duty Holders, Occupational Hygienists, LEV Designers, Health & Safety Professionals and Facilities Engineers.

LEVCentral Perspective

OCM8 reinforces one of the most important engineering principles promoted throughout LEVCentral:

Always choose the most appropriate engineering control for the hazard.

Within LEV, there can sometimes be a tendency to assume that local exhaust ventilation is the answer to every airborne contaminant problem. OCM8 demonstrates that this is not the case.

Where chemicals remain sealed during storage and only very small releases are reasonably foreseeable, there is often no identifiable point source from which contaminants can be captured. Under these circumstances, properly designed general ventilation may provide a more appropriate, simpler and more reliable control measure than attempting to install local extraction.

The guidance also illustrates another important point. Ventilation should never be viewed in isolation. Safe chemical storage depends upon a combination of suitable ventilation, compatible storage arrangements, spill management, competent supervision and effective housekeeping. Engineering controls work best when integrated into a wider system of risk management.

Further Resources

Recommended Learning

Thought Leadership

OCM8 serves as a useful reminder that ventilation is a family of engineering controls, not a single solution.

Local Exhaust Ventilation is highly effective where contaminants are released from an identifiable source, but many workplaces are better protected by carefully designed general ventilation that prevents contaminants accumulating throughout the space. The skill of the competent engineer lies in recognising which approach is appropriate.

For LEV professionals, this broader understanding is essential. Good occupational hygiene is not about specifying extraction wherever possible—it is about selecting the engineering control that most effectively reduces exposure while remaining practical, proportionate and reliable.

OCM8 demonstrates this principle well and provides a valuable complement to the more familiar guidance on Local Exhaust Ventilation.