M-Class Dust Extraction — The COSHH and CDM Standard for Construction, Woodworking and Regulated Dust
M-Class (Medium hazard) is the minimum dust extraction standard required by law for the majority of construction, maintenance and woodworking operations in the UK. Defined under EN 60335-2-69, an M-Class certified vacuum captures at least 99.9% of dust particles.
Working with asbestos or in an ICRA Type C or D clinical environment? M-Class is not sufficient — H-Class is required. Not sure which applies? Compare L, M and H side by side
What M-Class means technically
Under EN 60335-2-69, M-Class certification requires a vacuum to retain at least 99.9% of dust by weight across the complete machine — filter, dust bag, hose connections and motor exhaust. It is a whole-machine certification, not a filter rating.
M-Class machines are typically fitted with an H13 HEPA filter, which captures particles down to 0.3 microns. That is worth stating carefully, because the two things get confused: H13 describes the filter media, M-Class describes the certification of the assembled machine — tested with the filter, bag, connections and exhaust all in place. A machine can carry an H13 filter and still not be certified to any dust class, because it leaks at the seals or the bag change.
On regulated work it is the machine class that determines compliance, and the machine class that an inspector will ask about.
Filter grade versus machine class — the full explanation
Health-rated vacuum cleaners — why dust classification matters for workers, employers and unions
Where M-Class is legally required
Construction sites — CDM 2015 and COSHH 2002
Under CDM 2015 Regulation 15(2), M-Class extraction at source is the minimum standard for dust-generating operations on construction sites. Method statements that specify anything below M-Class for regulated dust operations are non-compliant.
M-Class covers general construction dust — concrete, mortar, block and brick. H-Class becomes the requirement where silica exposure is high, such as heritage stone and engineered stone.
Woodworking — hardwood, softwood and MDF
Wood dust is regulated under COSHH 2002 with specific Workplace Exposure Limits under HSE EH40. Hardwood dust has a WEL of 3 mg/m³ and is recognised as a carcinogen. HSE woodworking guidance points to at least M-Class equipment for cleaning wood dust, and M-Class extraction at source is the primary COSHH control measure for woodworking.
Where a COSHH assessment identifies a higher exposure risk on a specific operation, specify upwards.
Occupied buildings — maintenance and refurbishment
Any dust-generating maintenance work in an occupied building requires M-Class extraction at source under COSHH 2002.
Data centres and server rooms — ISO 14644-1 Class 8
H13 HEPA is the minimum filter grade for routine server room and comms room vacuum cleaning. Standard vacuums recirculate sub-micron particles through their exhaust — in a server room this disperses contamination onto equipment rather than removing it.
Because the work is around live equipment, the sealed containment of an H-Class machine is usually the right specification rather than filter grade alone. Where the hardware OEM references ISO 14644-1 Class 8 directly, H14 is required.
Data centre and server room cleaning hub
Social housing maintenance
Maintenance contractors in occupied social housing must use M-Class extraction. For damp and mould work the COSHH risk assessment sets the control level, with H-Class the prudent specification for significant remediation.
Healthcare — lower-risk areas
In ICRA Type A and B areas, M-Class is the minimum. For Type C and D, H-Class is mandatory.
Workshops — woodworking, metalwork, resin and composites
M-Class is the correct minimum for workshop dust extraction across timber, MDF, metal grinding, resin and fibreglass sanding. The dust you cannot see is the fraction that reaches the lungs. Standard shop vacuums and L-Class machines are not COSHH-compliant for regulated workshop dust.
V-TUF M-Class dust extractors and vacuums
V-TUF GRINDEX1100LP — 20L M-Class, 110V and 240V
Compact M-Class industrial dust extractor with HEPA+PTFE cartridge filter, manual reverse-flow filter cleaning and Longopac® continuous bagging. 200 m³/h airflow. For grinding, cutting, sanding and general construction or workshop dust. SKU GRINDEX1100LP-110 / GRINDEX1100LP-240.
V-TUF MIGHTY HSV — 21L M-Class, 110V and 240V
Autostart PTO for angle grinders, cut-off saws and fabrication tools. Sustained on-tool M-Class extraction. SKU MIGHTYHSV110 / MIGHTYHSV240.
V-TUF MIGHTY XL HSV — 37L M-Class, 110V and 240V
Larger capacity M-Class for higher-throughput site work. SKU MIGHTYXLHSV110 / MIGHTYXLHSV240.
V-TUF RUCKVAC-ION — cordless M-Class backpack, battery powered
300W brushless, H13 HEPA filter, 25.9V battery. Cable-free M-Class extraction for work where a mains supply is not available at the point of work.
V-TUF VXD30M240 — 30L M-Class stainless wet/dry vacuum, 240V
M-Class certified 30L stainless wet and dry vacuum with semi-automatic filter cleaning and tool-start auto-start. For dust extraction, liquid recovery and power-tool vacuum support. SKU VXD30M240.
M-Class vs L-Class
An L-Class machine retains 99% of dust. An M-Class machine retains 99.9%. On a sustained dust-generating operation, an L-Class machine passes ten times more fine dust back into the air than M-Class. L-Class is not an acceptable substitute for M-Class on any regulated dust operation.
Corded vs battery M-Class
The M-Class certification applies equally to corded and battery cordless machines. The compliance obligation does not change based on power source.
The three dust extraction classes
- L, M and H compared side by side — start here
- L-Class — 99% filtration. Low hazard and domestic use only
- M-Class — 99.9% filtration. The legal minimum for construction and regulated dust
- H-Class — 99.995% filtration. Mandatory for asbestos and clinical environments
- Health-rated vacuum cleaners — why dust classification matters for workers, employers and unions