INDG136 – Working with Substances Hazardous to Health: A Brief Guide to COSHH

Working with Substances Hazardous to Health: A Brief Guide to COSHH

INDG136 is HSE’s introductory guide to the Control of Substances Hazardous to Health (COSHH) Regulations. It explains how employers can identify hazardous substances, assess exposure risks and implement practical control measures to protect worker health.

The guide covers the broad range of substances that can cause ill health, including dusts, fumes, vapours, biological agents, chemicals, cleaning products and process-generated contaminants. It outlines the key COSHH principles of risk assessment, prevention of exposure, control measures, maintenance, monitoring, health surveillance and employee training.

For LEV professionals, COSHH forms the legislative foundation for many ventilation systems. Effective LEV is frequently the primary engineering control used to comply with COSHH requirements where hazardous airborne contaminants cannot be eliminated or substituted.

This resource is relevant to:

LEV Designers
LEV Installers
Occupational Hygienists
Health & Safety Professionals
Duty Holders
Facilities Managers
Process Engineers
Supervisors
Employers Managing Hazardous Substances

Source Document

View the HSE guidance here:

View Original HSE Guidance

Source: Health and Safety Executive (HSE)
Document Type: Guidance Leaflet
Status: Current
Last reviewed by LEVCentral: June 2026

LEVCentral Expert Commentary

INDG136 is one of the most important introductory health-risk management documents published by HSE. While not specifically focused on LEV, it provides the regulatory context that drives the need for effective ventilation systems in many workplaces.

The document reinforces the principle that employers must first understand the hazardous substances present within their operations before selecting appropriate control measures. Where airborne exposure cannot be adequately controlled through elimination or substitution, LEV often becomes the preferred engineering solution.

For LEV professionals, the guide is particularly useful because it explains the wider COSHH framework into which ventilation systems must fit. An effective LEV installation is only one component of a compliant control strategy and must be supported by suitable maintenance, user training, examination and testing, and ongoing management controls.

The guidance also provides useful examples of hazardous substances encountered across different industries, helping duty holders understand why airborne contaminant control remains a fundamental occupational health requirement.

Organisations seeking a defensible approach to occupational hygiene should ensure COSHH assessments and LEV management arrangements are closely integrated rather than treated as separate activities.

Further Resources

HSG258 – Controlling Airborne Contaminants at Work (LEV)
Clearing the Air – A Simple Guide to LEV
INDG409 – Time to Clear the Air! A Workers’ Pocket Guide to LEV
G406 – New and Existing Engineering Control Systems
LEV Information for Employees and Users

Recommended Learning

P602 LEV Design Principles
P600 Methods for Testing Effectiveness of LEV
P601 Thorough Examination and Testing of LEV Systems
LEV Management and Governance

Thought Leadership

Defensible LEV Commissioning
LEV Governance and Duty Holder Assurance
Commissioning vs TExT – Understanding the Difference
Building a Defensible LEV Compliance Strategy