Machining processes generate aerosols, vapours and particulates from metalworking fluids (MWFs), coolants, oils, and the cutting action itself. These contaminants can affect lungs, skin, eyes, machine reliability, housekeeping, lighting and even slip/fire risks.
Because droplets and particles are often invisible, the risks are easy to underestimate – until production quality, operator health or inspections are impacted.
Below are the most frequent hazards you will encounter. Each includes where it comes from, why it matters, and typical control considerations.
Source
High‑speed turning, milling, drilling and grinding with neat (straight) oils; heat and shear generate fine droplets.
Hazard
Inhalation and skin contact risks; can aggravate asthma and respiratory issues; settles on floors and equipment causing slips, poor visibility and housekeeping burdens; potential ignition risks in poorly controlled environments.
Control measures
Capture at source via suitable LEV (mist extraction), closed doors/guards, correct enclosure negative pressure, good maintenance and appropriate filtration media.
Source
Emulsified MWFs atomised at the tool-work interface; through‑spindle coolant and high‑pressure systems.
Hazard
Respiratory irritation, occupational asthma/hypersensitivity pneumonitis risks; dermatitis from skin contact; can carry bioburden (bacteria/fungi) if fluids are poorly controlled.
Control measures
Effective capture and filtration; fluid management (concentration, pH, tramp oil control); enclosures shut; avoid visible misting; maintain LEV to keep exposure ‘as low as reasonably practicable’.
Source
Thermal processes (hard turning, grinding, EDM) and hot chips generating sub‑micron smoke that can bypass basic separation.
Hazard
Fine particulates penetrate deep into lungs; challenging to capture without the correct filter stages.
Control measures
Use systems rated for smoke (high‑efficiency coalescent and final/HEPA stages); verify capture velocities and seal integrity.
Source
Dry machining, deburring, polishing, additive manufacturing support removal, some composite/plastic machining.
Hazard
Inhalable/respirable dust risks; may be combustible depending on material.
Control measures
Application‑matched extraction (mist vs dust are different), housekeeping, explosion protection where applicable.
Source
Additives/cleaners, degraded MWFs, solvents.
Hazard
Eye/airway irritation, comfort/productivity impacts.
Control measures
Fluid care, suitable filtration stages (e.g. activated carbon where appropriate), substitution and process optimisation.
COSHH (Control of Substances Hazardous to Health): Requires you to assess risks, prevent or adequately control exposure, maintain control measures, provide information/training, and arrange appropriate health surveillance where indicated.
LEV (Local Exhaust Ventilation): If you use extraction as a control, it must be properly designed, commissioned, and maintained.
Risk assessment and hierarchy of control: Eliminate, substitute, engineer (LEV), administrative measures, then PPE/RPE as a last line.
Commissioning of LEV:
New or modified systems must be commissioned to prove they achieve adequate control in your process.
Thorough Examination and Test (TExT):
Most LEV systems require a thorough examination and test at least every 14 months (some processes more frequently). Keep records.
Operate and maintain:
Keep systems in ‘efficient working order’; ensure operators know how to use and check them.
Health surveillance where appropriate:
E.g. for risks of dermatitis or asthma when working with MWFs.
About exposure limits:
There is no current UK WEL (Workplace Exposure Limit) for oil mist or water‑mix MWF mist. Practically, this means you must reduce exposures as low as reasonably practicable (ALARP) and demonstrate effective control.
✔ Protects health:
Reduce respiratory/skin risks from mists, smoke and aerosols; support a cleaner, brighter working environment.
✔ Demonstrates compliance:
A commissioned, well‑maintained LEV system with records puts you on the front foot for inspections.
✔ Improves reliability and quality:
Keep optics, sensors and electrics cleaner; stabilise process conditions; reduce rework linked to contamination.
✔ Cuts housekeeping and slip/fire risks:
Less residue on floors, fixtures and lights; reclaim oil where appropriate.
✔ Supports morale and retention:
Cleaner air is a visible investment in operator wellbeing.
Jemtech partners with HFiltration to provide application‑matched solutions for mist, smoke and dust. The three core ranges below cover single machines through to centralised systems and harsher smoke applications.
Best for:
Individual CNCs producing oil/coolant mist at typical speeds/pressures.
How it works:
Polluted air is drawn into a centrifugal filter (mesh‑protected intake prevents swarf entry). Droplets are thrown out by centrifugal force; optional stages address finer fractions. Electrostatic options are available for certain duties.
Key benefits:
Compact machine‑mount options; proven, energy‑efficient removal of oil mist; helps maintain enclosure negative pressure; reduces visible mist, odour and residue.
Typical outcomes:
Clearer air around the machine; fewer mist alarms/door plumes; improved housekeeping.
Efficiency:
300m³/h to 2300m³/h
Best for:
Higher‑duty and multi‑machine installations; emulsified oil mists; where verified high capture efficiency and easy service access are priorities.
How it works:
Pleated glass‑fibre cartridges with high‑grade efficiency (up to H13 with options); large inspection panels; configurable extras (final filters, silencers, differential pressure monitoring).
Key benefits:
Suited to centralised systems; robust performance for demanding coolant‑mist applications; scalable airflow and static pressure for longer duct runs.
Typical outcomes:
Consistent plant‑wide air quality; simplified maintenance; strong compliance evidence via DP checks and inspection access.
Efficiency:
1500m³/h to 14000m³/h
Best for:
Processes generating finer smoke/condensable fumes (e.g., hard turning/grinding, thermal effects) and difficult aerosols.
How it works:
Multilayer glass‑fibre media promotes true coalescence; micro‑particles agglomerate while passing through progressively denser layers, forming drainable droplets. Integrated‑fan variants are available to simplify installation.
Key benefits:
High removal efficiency on sub‑micron particles; handles harsher conditions than basic mist units; options to mount within or close to the machine to save space and reduce noise.
Typical outcomes:
Noticeably clearer cabins/aisles even on challenging smoke‑prone operations; easier compliance demonstration for fine‑particle duties.
Efficiency:
2000m³/h to 8000m³/h – 99.99% filtration of particles
✔ End‑to‑end support:
Application survey, selection, and sizing; electrical/mechanical installation by qualified technicians.
✔ LEV commissioning and records:
We commission systems to verify technical performance and control effectiveness for your specific processes, providing the baseline for future TExT.
✔ Planned maintenance:
Filter changes, integrity checks, DP monitoring, fan/duct inspections to keep capture performance consistent and energy‑efficient.
✔ TExT and air monitoring:
Support with 14‑month thorough examination and test cycles (or as required) and air monitoring where appropriate.
✔ Minimise downtime and cost:
Proactive service prevents failures, extends equipment life and maintains compliance.
✔ Jemtech offers a no‑obligation survey:
to review your current extraction, risks and compliance posture, and to recommend practical improvements.
Walk the shop:
Identify visible mist, ‘foggy’ enclosures, odours, slippery residues, stained lights, and areas where doors are frequently opened mid‑cycle.
Check enclosures:
Doors/guards should stay shut; confirm seals and negative pressure (no mist plume when doors open).
Verify LEV basics:
Capture points correctly positioned; ducting intact; filters in service date; DP readings recorded; drains clear.
Keep fluid healthy:
Maintain concentration/pH, remove tramp oil, clean sumps, and control bacteria (dipslides, routine checks).
Train and brief:
Operators should recognise mist controls, pre‑use checks, and reporting routes.
Plan TExT and maintenance:
Put the 14‑month cycle on the calendar; keep commissioning and service records accessible for inspections. We also recommend the internal filters of the units to be changed every six months
Escalate issues early:
Rising DP, visible haze, or odours usually mean filters or capture set‑up need attention.
CNC machining can generate airborne oil mist, coolant mist, smoke and fine dust depending on the process and cutting fluid. These hazards can cause respiratory irritation, occupational asthma, dermatitis, poor visibility, slip hazards and potential fire risks if not controlled.
Beyond airborne contaminants, hazards include moving parts (entanglement/crush), flying chips, noise, vibration, electrical risks, and poor ergonomics. Good machine guarding, regular maintenance, and appropriate extraction all reduce these risks.
Yes. Under UK COSHH regulations, employers must control exposure to mist, fumes and dust. Well‑designed Local Exhaust Ventilation (LEV) or mist extraction systems are the most effective way to keep exposures as low as reasonably practicable and maintain compliance.
1. Keep machine doors and guards closed during operation.
2. Ensure mist extraction or LEV is running and functioning correctly.
3. Wear appropriate PPE if required by risk assessment.
4. Check coolant levels and concentration to reduce misting and bacterial growth.
5. Conduct pre‑use checks: look for leaks, broken seals, damaged ducts or filters.
6. Train operators to recognise mist problems (visible haze, odours, alarms) and report them promptly.
LEV systems must undergo a thorough examination and test at least every 14 months (sometimes more often depending on process), with routine visual inspections and filter maintenance and replacement in between to ensure consistent performance.
Poor control can lead to health issues, HSE enforcement action, housekeeping problems, machine downtime, and reduced part quality. It also makes inspections and compliance evidence difficult.
Jemtech has been a specialist in UK machining workshop products and services for decades, specialising in metalworking fluid management and air quality solutions. By combining expertise in both coolants and mist extraction, Jemtech provides an integrated approach to controlling airborne hazards and keeping processes stable.
Specialist knowledge:
Deep understanding of machining processes and how mist generation links to coolant type, pressure, and machine design.
Full‑service provider:
From site survey and system design to installation, commissioning, and ongoing maintenance.
Proven partnerships:
Jemtech supplies industry‑leading HFiltration products, selected to suit applications ranging from single‑machine installations to centralised plant systems.
Compliance assurance:
Detailed commissioning records, LEV documentation, and planned service schedules give clear evidence for inspectors.
Focus on people and productivity:
Cleaner air supports operator health, morale, and retention, while protecting equipment and ensuring consistent component quality.
Whether you’re tackling visible mist, addressing inspection findings, or planning a new facility, Jemtech offers practical solutions and the guidance to stay ahead of compliance requirements.