What is LEV?

Local Exhaust Ventilation (LEV) is a vital engineering control measure designed to protect workers’ lungs and keep workplaces clean, safe, and compliant. By capturing dusts, fumes, mists, vapours, and gases at source—before they can spread into the air—LEV significantly reduces inhalation exposure and reliance on personal protective equipment. When correctly designed, used, and maintained, LEV systems play a critical role in safeguarding health, improving air quality, and meeting legal duties under the Control of Substances Hazardous to Health (COSHH) Regulations.

LEV stands for Local Exhaust Ventilation.

In plain terms, it’s a system designed to capture and remove harmful substances at source, before they can spread into the workplace air and be breathed in.

What LEV does

LEV systems are used to control exposure to things like:

  • Dusts (wood, metal, flour, powders, etc.)
  • Fumes (welding, soldering, melting)
  • Mists (oil mist, coolant spray)
  • Vapours and gases (solvents, chemicals)

Instead of trying to clean the whole room, LEV captures the contaminant right where it’s generated.

Why LEV is important

HSE statistics indicate that around 12,000 people die each year in the UK from occupational lung disease and work-related cancer. These deaths are the direct result of exposure to harmful substances in the workplace.

Despite recent HSE initiatives aimed at reducing these figures, the statistics remain largely unchanged. While these initiatives are welcome, they cannot succeed in isolation. Meaningful improvement will require sustained action and support from across a wide spectrum of organisations, professional bodies, employers, and regulators. Political leadership also has a critical role to play.

Beyond the devastating human cost to individuals and their families, the wider impact is significant. The British Lung Foundation estimates that respiratory disease costs the NHS approximately £4.7 billion every year, placing a substantial and ongoing burden on public health services.

There is no single cause—and no single solution—to this situation. Multiple factors contribute, chief among them a poor understanding of the long-term consequences of exposure to workplace contaminants, such as dusts, fumes, vapours, and mists. This is often compounded by a strong sense of optimism bias among those exposed:

“I’ll be all right. I worked there yesterday and I’m still OK today.”

If a comparable number of deaths occurred each year as a result of an immediate disaster—such as a gas explosion or a transport accident—it would provoke national outrage. In contrast, deaths from occupational respiratory disease often attract far less attention because they occur slowly, quietly, and years after the exposure.

The absence of a dramatic event does not reduce the scale of the tragedy—only its visibility.

 Basic Components of an LEV System:

  • The hood is where the harmful
    substance enters the LEV system.

  • The duct transports the harmful substance from the hood to the aircleaner/filter.

  • The aircleaner (more commonly called a filter) removes the harmful substance and cleans the
    airstream (not all systems will require an aircleaner).

  • The air mover (more commonly known as the fan).  This generates the pressure required to make the air move.

  • The stack/discharge is required to exhaust the fumes to a safe place.

Examples of LEV Systems

(This is not exhaustive)

Welding fume - Capture Type

Welding Fume - On torch

Fume cupboards

Acid fume with scrubber

Sander dust extraction

Shotblaster dust extraction

Roles and Responsibilities

Employers

Employers have a legal duty to protect their employees and any visitors who may be affected by workplace activities.

The COSHH Hierarchy of Control must be considered first to determine whether exposure can be eliminated or reduced by means other than Local Exhaust Ventilation (LEV). Where exposure cannot be adequately controlled by alternative measures, LEV (or Industrial Ventilation) must be provided to reduce exposure as low as reasonably practicable.

Where LEV/IV is used, employers should understand:

  • The processes carried out in the workplace and the potential sources of airborne contaminants
  • The properties and behaviour of those contaminants (dusts, fumes, vapours, mists, etc.)
  • The level of control required and the operational needs of employees
  • How the system should be used, maintained, and how often it must be tested and examined

Employers are also responsible for ensuring that LEV systems are properly used, maintained, and thoroughly examined and tested at least every 14 months, in accordance with COSHH Regulation 9 and HSG258.

Employees

Employees and operators have a duty to use the control measures provided by their employer correctly and as intended. They must also report any faults, damage, or reduced performance of LEV/IV systems without delay.

In many workplaces, employees may also be responsible for carrying out routine (weekly) checks of LEV systems.

Employees should know:

  • How to correctly position and use the LEV/IV equipment
  • What to do if there is a problem and how to report it
  • How to carry out simple routine checks of the system

Correct employee use is critical — even a well-designed LEV system will not protect health if it is used incorrectly.

Suppliers

Suppliers provide specialist services across the LEV/IV lifecycle. These are typically delivered by LEV engineers and occupational hygienists, and may include one or more of the following roles:

  • Sales – advising on and supplying suitable LEV/IV solutions
  • Designers – interpreting the employer’s requirements and producing system designs for approval
  • Manufacturers – manufacturing systems to the approved design specification
  • Installers – installing the system in accordance with the design drawings
  • Commissioners – setting up and verifying system performance, typically when first installed
  • Testers – carrying out Thorough Examination and Test (TExT) in line with COSHH and HSG258 and producing formal reports
  • Service engineers – servicing, maintaining, and repairing LEV/IV systems

Some suppliers offer a complete end-to-end service, while others specialise in specific parts of the LEV/IV chain. Regardless of the scope of service, any supplier appointed by the employer must be competent to carry out the work.