BOHS M505 Student Manual – Control of Hazardous Substances

LEVCentral Expert Commentary

The BOHS M505 – Control of Hazardous Substances module is one of the core qualifications within the BOHS Certificate of Operational Competence in Occupational Hygiene (CertOH). It introduces the principles of controlling occupational exposure to hazardous substances and bridges the gap between hazard recognition and the practical implementation of effective control measures.

The accompanying BOHS Student Manual is much more than an examination handbook. It provides a comprehensive overview of how hazardous substances are generated, how exposure occurs and, most importantly, how effective control strategies should be selected, designed and implemented in accordance with the hierarchy of control.

One of the manual’s greatest strengths is the emphasis it places on engineering controls, particularly Local Exhaust Ventilation (LEV). It explains the principles of contaminant generation, the concept of “adequate control” under COSHH, process and workplace design, general ventilation, LEV systems, enclosure techniques, personal protective equipment and the importance of adopting a holistic approach to exposure reduction.

For LEV practitioners, M505 provides valuable context by placing ventilation within the wider occupational hygiene framework. Rather than viewing LEV as an isolated engineering solution, the manual demonstrates how ventilation integrates with elimination, substitution, process modification, enclosure, administrative controls and personal protective equipment to achieve effective long-term exposure control.

View BOHS M505 Student Manual

BOHS M505 Student Manual

Key Learning Points

The manual provides detailed guidance on:

How hazardous substances are generated within workplace processes.
Routes of exposure and their significance.
The Hierarchy of Control.
The meaning of “adequate control” under COSHH.
Process and workplace design to minimise exposure.
Elimination and substitution strategies.
General ventilation.
Local Exhaust Ventilation (LEV).
Hood types and enclosure design.
Assessing LEV performance and recognising system limitations.
Personal Protective Equipment (PPE) and Respiratory Protective Equipment (RPE).
Administrative controls.
Developing integrated control strategies.
Taking a holistic approach to occupational exposure control.

Source Document Information

Organisation: British Occupational Hygiene Society (BOHS)

Document: M505 Student Manual – Control of Hazardous Substances

Document Type: BOHS Student Manual

Primary Topics: COSHH, Engineering Controls, LEV, Exposure Control, Occupational Hygiene

Audience: Occupational Hygienists, LEV Professionals, Health & Safety Practitioners, Process Engineers, Students and Duty Holders.

LEVCentral Perspective

Although developed as the official learning manual for the BOHS M505 qualification, this publication deserves recognition as one of the best practical introductions to exposure control available.

Unlike publications that focus exclusively on ventilation, M505 places LEV within the broader philosophy of occupational hygiene. It explains that the objective is not simply to extract contaminants, but to prevent worker exposure by selecting the most appropriate combination of control measures.

For LEV engineers, this wider perspective is invaluable. It reinforces that a well-designed extraction system should support the hierarchy of control—not replace it. In many situations, improvements to process design, enclosure or material selection may significantly reduce the demands placed upon the ventilation system, resulting in safer and more efficient solutions.

Further Resources

Recommended Learning

Thought Leadership

The M505 manual illustrates an important evolution in occupational hygiene. Historically, exposure control often centred on measuring airborne contaminants and then introducing ventilation where necessary. Modern practice takes a much broader view, considering process design, material substitution, automation, enclosure and engineering controls as part of an integrated strategy.

This systems-based philosophy aligns closely with the direction of modern LEV practice. Effective ventilation should not be viewed as the first solution to every exposure problem, but as one element within a carefully considered hierarchy of controls.

Understanding this wider context enables engineers and occupational hygienists to develop solutions that are not only technically effective but also robust, proportionate and sustainable throughout the life of the process.