HSE EH40 — Workplace Exposure Limits for Dust and Hazardous Substances

HSE EH40 — Workplace Exposure Limits

HSE EH40 is the Health and Safety Executive's document setting out the Workplace Exposure Limits (WELs) for hazardous substances in Great Britain. WELs are legally enforceable under COSHH Regulation 7 — employers must not exceed them and must keep exposure as low as reasonably practicable below them.

For dust extraction and pressure washing equipment buyers, EH40 is the document that tells you exactly what the permissible exposure limit is for the substances your workers are handling — and therefore what classification of extraction equipment is legally required.

The key WELs for construction and industrial cleaning

The most commercially relevant WELs for V-TUF customers are:

Respirable crystalline silica (RCS): 0.1 mg/m³ TWA (8-hour time-weighted average). This is the lowest WEL for any commonly encountered construction dust and the most frequently exceeded in enforcement actions. Silica is present in concrete, brick, mortar, stone, and many engineered materials. Any cutting, grinding, drilling or chasing of these materials without on-tool extraction can breach this limit within minutes of starting work. H-Class extraction is required where RCS dust is generated.
Asbestos fibres: EH40 sets a control limit of 1 fibre per millilitre of air (f/ml) averaged over 4 hours for all asbestos types, with a short-term limit of 3 f/ml averaged over 10 minutes. Unlike most WELs, asbestos fibre limits are absolute — they may not be exceeded under any circumstances. In practice, the Control of Asbestos Regulations 2012 (CAR 2012) imposes requirements that go beyond the WEL framework: H-Class extraction is mandatory for all asbestos vacuum work regardless of measured fibre concentration. See Control of Asbestos Regulations 2012 →
Hardwood dust: 3 mg/m³ TWA. Hardwood dust is a known carcinogen (Group 1, IARC). M-Class extraction is the minimum; H-Class is recommended for sustained woodworking operations. On-tool extraction is the most effective control.
Softwood dust: 5 mg/m³ TWA. M-Class extraction required for sustained operations.
General inhalable dust (not otherwise specified): 10 mg/m³ TWA / Respirable dust: 4 mg/m³ TWA. The baseline limits that apply where no substance-specific WEL exists. M-Class extraction is typically required for construction work generating these dusts.
Grain dust: 10 mg/m³ TWA. Relevant to agricultural and food sector customers. M-Class extraction minimum for grain handling environments.
Flour dust: 10 mg/m³ TWA. Relevant to food manufacturing and bakery customers.

How WELs relate to extraction classification

The M-Class and H-Class extraction classifications are not arbitrary standards — they are calibrated specifically to the WEL framework in EH40. The HSE guidance on dust extraction (HSG258 — Controlling Airborne Contaminants at Work) sets out the relationship:

H-Class extraction is required where the dust WEL is at or below 0.1 mg/m³ — which in practice means silica dust, asbestos fibres and other carcinogenic substances. H14 HEPA, 99.995% filtration efficiency at 0.3 microns.
M-Class extraction is required where the dust WEL is between 0.1 mg/m³ and 1 mg/m³ — covering most general construction and woodworking dusts. H13 HEPA, 99.9% filtration efficiency.
L-Class extraction is acceptable where the dust WEL exceeds 1 mg/m³ and the dust is not otherwise classified as hazardous. Standard building debris, dry soil.

Recommended V-TUF equipment by WEL category

For RCS / silica-generating work and asbestos (WEL 0.1 mg/m³ and below)

V-TUF MIDI H-Class — 21L H-Class

H14 HEPA, 99.995%. Required for cutting, grinding, drilling and chasing of concrete, brick, stone and mortar, and mandatory for all asbestos vacuum work under CAR 2012. SKU MIDIH110 / MIDIH240. View MIDI H-Class →

For general construction dust (WEL 0.1–1 mg/m³)

V-TUF MIGHTY HSV — M-Class, 21L

H13 HEPA, 99.9%. The volume M-Class extractor for sustained construction site use. Autostart power take-off. SKU MIGHTYHSV110 / MIGHTYHSV240. View MIGHTY HSV →