What is Local Exhaust Ventilation (LEV)?
Local Exhaust Ventilation systems take dust, mists, gases, vapour or fumes out of the air so that they can’t be breathed in. A typical LEV system will have:
- Hood(s) to collect airborne contaminants at, or near, where they are created (the source).
- Ducts to carry the airborne contaminants away from the process.
- An air cleaner or filter to remove the contaminant and clean the extracted air.
- A fan to move the air around the system, which must be the right size and type to deliver sufficient air flow to the hood.
- An exhaust for the safe release of cleaned, extracted air into the atmosphere or back into the workplace.
What are the regulations?
Local exhaust ventilation systems are covered under the Control of Substances Hazardous to Health Regulations (COSHH). Additional guidance is provided in HSG258: Controlling airborne contaminants at work: A guide to local exhaust ventilation (LEV)
What are the requirements for LEV testing?
For most systems, a Thorough Examination is required under COSHH at least once in every 14 months. There are some exceptions to this, such as:
- Processes in which blasting is carried out in or incidental to the cleaning of metal castings in connection with their manufacture, which should be examined monthly.
- Processes, other than wet processes, in which metal articles (other than gold, platinum or iridium) are ground, abraded or polished using mechanical power in any room for more than 12 hours a week. These should be examined every 6 months.
- Processes giving off dust or fume in which non-ferrous metal castings are produced. Again, these should be examined every 6 months.
Depending on the process and the substance to be controlled more frequent examinations may be recommended for systems deemed to present a high risk.
Our team provides thorough examinations by BOHS trained personnel (P601), which conform to the latest Health Safety Executive Guidance (HSG258) and highlight:
- Contaminant control failings
- Maintenance issues
- Damage to systems
- Practical advice on improvements
Our aim will always be to give practical and cost-effective advice and guidance to customers to complement their COSHH assessments.
We believe that those carrying out LEV should be independent. We do not supply, install or maintain systems, which eliminates any possible conflict of interest.
What is the purpose of a Thorough Examination of an LEV (Local Exhaust Ventilation) System
It is a check that your LEV is still working as effectively as originally intended and is helping to protect your employees’ health. To be able to tell if it is still working as it should, you should be able to provide the examiner with information about the intended or designed performance of your system e.g. hood type and position relative to the process, airflow and other measurements. If this information is not available, you will need to seek competent advice.
What Information does the examiner need?
To assess if the LEV is still working properly, the examiner ideally needs to know what it was originally intended to do. When you obtained the LEV equipment, the supplier should have conducted an LEV test on installation (or ‘commissioned’ it) to check it was working effectively and providing the necessary protection, as specified. Where this information is not available the examiner may be able to help you identify intended performance information.
How do I choose a supplier to design and/or install an LEV system?
The HSE has produced a guide to help you with this, Clearing The Air – A simple guide to buying and using local exhaust ventilation (LEV).
You should ask any potential supplier to prove that they are competent, for example through previous work and professional qualifications. Only buy LEV that will adequately control exposure and ask the supplier how they will prove this.
The supplier of an LEV system should provide you with some key documentation:
- A user manual with a general specification of what the LEV system is designed to control and how it achieves that control.
- A logbook for the system.
- A commissioning report.
This documentation is essential for maintaining your system and ensuring that the system continues to perform as intended.