In the UK alone, thousands of people each year develop lung diseases as a result of their occupation, such as COPD, asthma and even cancer. These can go on to cause permanent disablement, preventing the sufferer from ever working again, or even be fatal.

Occupational lung disease occurs when someone breathes in dust, fumes, or dangerous airborne contaminants in their workplace. Many industries are affected, from medical lab research to woodworking, and everything in between.

The sad truth for those affected is that it can be easily avoided if effective control measures are put in place. Installing a local exhaust ventilation (LEV) system to extract harmful substances from the atmosphere will minimise the risk of exposure to your workers and help safeguard them from harm. Unfortunately, research by the Health and Safety Executive (HSE) has revealed that many employers of at-risk workers are not aware that their employees’ health is in danger.

What Is LEV?

In its simplest terms, a LEV system is an extractor fan, which pulls the harmful dust or fumes away from its source, minimising exposure to workers. A hood is used to enclose the source of the contaminant, while a fan generates air flow; meanwhile, air is conducted from the hood through duct work to a filter which removes harmful particles from the extracted air, and finally the safe air is discharged into the atmosphere.

There are many kinds of LEV systems, and the type used will depend on the properties of the airborne contaminant, the work processes involved which generate the contaminant, the work environment, and the needs of the operator working with the sources.

Legal Requirements For LEV Systems


There are several pieces of legislation which apply to employers working with potentially hazardous substances, and who therefore require LEV extraction:

HSE-logo1The Health and Safety Executive has also issued supplementary guidance on deciding on, designing, commissioning and testing effective LEV:

Each of these regulations sets out statutory requirements for employers whose staff work in an environment which requires LEV extraction. It’s vital to adhere to these guidelines to be compliant – and more importantly, safeguard the health of your employees. 

Requirements include daily, weekly and monthly in-house checks to ensure the system continues to run properly, regular maintenance, and thorough testing. Most companies adhere to the first two of these requirements.

Why LEV Testing Is Important

The daily, weekly and monthly checks on a LEV which can be performed by a trained member of staff are fairly straightforward – they just need to know the parts of the system, their function, and how to recognise if a part is damaged. Maintenance engineers require a higher level of knowledge – they must know how the LEV system works, how to recognise and assess hazards, how to perform routine maintenance and performance checks and how to record and report them.

Testing calls for real expertise on the legal requirements around LEV systems, proficiency with measurement and assessment instruments, knowledge on the standards to which each part of the system should perform, how to recognise which part of the system is not working to the required standard, and how to test if the LEV is effective in reducing exposure to airborne contaminants.

Ultimately, regular checks and maintenance will keep your LEV system running – but only thorough testing will identify if there are any faults with the machine which could be putting your staff at risk, and ensure that the system continues to control the level of exposure. 

How Does LEV Testing Work?

COSHH regulations dictate that LEVs must have maintenance, examination and testing of control measures at regular/ scheduled intervals. HSG258 expands on COSHH sets out 3 stages to LEV testing:

  1. A thorough visual and structural examination to verify the LEV is in efficient working order, in good repair and in a clean condition.
  2. Review of the technical performance to check conformity with commissioning or other sources of relevant information.
  3. Assessment of control effectiveness.

After testing, the examiner will be able to confirm if the system is unsafe or if contaminant control is still sufficient that the LEV can continue to be used, and a test certificate will be issued.

Need Your LEV Tested?

CHTS is expert in the examination and testing of LEV systems. Our engineers are BOHS IP601 certified – the official qualification from the Chartered Society for Worker Health Protection in the thorough examination and testing of Local Exhaust Ventilation systems. We can ensure that your LEV system is working to the highest possible standards and continues to protect your staff from hazardous substances. In addition, we’ll advise you on whether you should have your system tested more frequently, as set out by COSHH & HSG258, depending on your system’s application.

If your system does not pass the HSG258 tests, we can undertake all remedial works, such as supplying and installing replacement fans or LEV extraction arms.


If you’d like to arrange testing of your LEV systems, get in touch today