LEV109: On-Torch Extraction

Guidance for Control of MIG Welding Fume Exposure

Welding fume control has changed — permanently.

Since the International Agency for Research on Cancer (IARC) reclassified mild steel welding fume as a Group 1 human carcinogen, the UK Health and Safety Executive (HSE) has made it clear: all welding fume must be controlled, without exception. Yet on sites across the UK, on-torch extraction systems are still misunderstood, poorly maintained, or relied upon without any real assessment of whether they’re actually working.

LEV109: On-Torch Extraction was written to close that gap between assumed control and real control.

This guide provides clear, practical, field-based guidance on how on-torch extraction systems really perform, how they fail, and how to assess them properly during a COSHH Regulation 9 Thorough Examination and Test (TExT).

A Practical Guide to Real-World Fume Control

On-torch extraction can be an effective engineering control — but only when it is correctly specified, maintained, and used. In practice, many systems capture far less fume than expected due to damaged shrouds, leaking hoses, blinded filters, misused air bleeds, or simple lack of understanding.

LEV109 explains what’s actually happening at the torch.

Written for engineers, LEV testers, duty holders, and health & safety professionals, the guide breaks down the entire system — from torch to filter — showing how each component affects capture efficiency at the weld.

Inside, you’ll find practical guidance on:

• MIG welding fume characteristics and health risks

• Legal duties under COSHH and current HSE expectations

• The hierarchy of control for welding fume

• How on-torch extraction systems work — and their limitations

• Torch design, shroud types, and shroud condition

• Flexible hose damage, leakage, and airflow losses

• Filter units, filtration classes (W1, W2, W3), and DIN EN ISO 21904-2

• Filter cleaning methods and differential pressure monitoring

• Air bleeds — why they exist, how they’re misused, and how they affect capture

• Measuring airflow at both the filter inlet and the torch

• Typical real-world losses (often 50–75%) between unit and torch

• Performance issues during corner and confined welding

• When LEV must be supplemented with RPE

The guide also includes structured checklists, worked examples, and site notes to support consistent and defensible TExT assessments.

Why This Matters

Welding fume doesn’t just affect welders.

Poorly controlled fume spreads throughout the workspace, exposing nearby workers, supervisors, and maintenance staff to hazardous metal particulates — including manganese, hexavalent chromium, nickel, and zinc oxide.

Common failures seen on site include:

• Missing or damaged torch shrouds

• Air bleeds left permanently open

• Crushed, holed, or UV-damaged flexible hoses

• Filters blinded by lack of cleaning

• Recirculating units without effective secondary filtration

• Systems assumed to work, but never properly measured

LEV109 helps practitioners identify these failures early, understand their impact on exposure, and take proportionate corrective action — protecting both health and compliance.

Who This Guide Is For

LEV109 is essential reading for:

• Welding engineers and workshop managers

• LEV engineers and COSHH assessors

• Occupational hygienists

• Health & safety professionals

• Duty holders responsible for welding fume control

Whether you’re specifying systems, inspecting them, testing them, or relying on them to protect workers, this guide gives you the technical understanding needed to make informed decisions.

Product Details

• Title: LEV109: On-Torch Extraction – Guidance for Control of MIG Welding Fume Exposure

• Series: LEV Academy Technical Guides

• Format: Digital guide (PDF)

• Focus: Practical assessment and control of on-torch extraction systems

• Author: Louise Davies Wood

• Published: November 2025

• Applicable Standards: COSHH Regulations, HSE Guidance, DIN EN ISO 21904-2