Local exhaust ventilation (LEV) is a method of reducing workers’ exposure to potentially harmful substances generated by the work process. The release of the substances is controlled at, or close to the point of release reducing the potential for the substance to be released. A typical LEV system will extract air using a hood, partial enclosure or other opening and transport the contaminated air away from the workplace, cleaning it and then discharging it either outside or back into the workplace.
Local exhaust ventilation (LEV) can be used to control a wide range of substances including gases and vapours, fume and solids.
In the UK the Control of Substances Hazardous to Health (COSHH) Regulations 2002 require that thorough examination and testing of LEV plant is carried out at least once 14 months and in some instances (e.g. shot blasting units, grinding extracts), at shorter intervals. The Control of Lead at Work Regulations 2002 (CLAW) have similar requirements for examination and testing of local exhaust ventilation plant.
In the UK the law specifies that the person undertaking the examination and testing must be competent to do so (The Management of Health and Safety at Work Regulations 1999). In its publication HSG258 “Controlling airborne contaminants at work. A guide to local exhaust ventilation (LEV)” the Health and Safety Executive lists four qualifications as being suitable:
CDI Facilities has trained and qualified occupational hygienists who can undertake thorough examination and testing of LEV systems. All LEV projects are managed by personnel holding either the BOHS Certificate of Operational Competence in Occupational Hygiene (Cert. Occ. Hyg.) or the Diploma of Professional Competence in Occupational Hygiene (Dip Occ Hyg).
Many organisations undertaking examination and testing are still working to guidance note HS(G) 54 which has been superseded. The latest guidance on the examination and testing of local exhaust ventilation is given in the Health and Safety Executive’s publication HSG258 “Controlling airborne contaminants at work. A guide to local exhaust ventilation (LEV)”.
It is essential to ensure that work is being undertaken by trained staff who are familiar with this guidance.
Environmental Evaluation’s occupational hygiene team are fully conversant with the requirements of HSG 258.
A company specialising in the provision of services such as the examination and testing of local exhaust ventilation systems is likely to have a quality management system registered to ISO 9001 and will have or be working towards UKAS accreditation to ISO 17020.
The thorough examination and testing of a local exhaust ventilation (LEV) system will involve three stages:
Stage 1. The thorough examination: will include the inspection of the following
Stage 2. Measuring technical performance could include measurement of:
Stage 3. Assessment of the LEV system’s control effectiveness will include:
LEV examination and test reports produced by Environmental Evaluation follow a HSE approved format and include measurement test data, schematic diagrams of the LEV systems, an assessment on the control effectiveness of the system and any recommendations for remedial requirements detailed in a prioritised action plan. Local exhaust ventilation design advice can also be provided to ensure that effective control is achieved.
Records of all tests should be kept for at least five years.
There is no prescribed format for keeping your report but it should be accessible, some employers keep the records in paper format, others prefer electronic storage.
The cost of the examination and testing will depend on several factors, including:
CDI Facilities will be pleased to provide a firm and fixed quotation for the examination and testing.
To obtain a quotation for the examination and testing of your local exhaust ventilation system(s), please complete the contact form here.
A visual check of the equipment should be carried out by maintenance staff at least once a week. Employees using the LEV system must report any defects as soon as they are noticed. Thorough examination and testing of the LEV system, undertaken by suitably qualified personnel, are required at least once every fourteen months (more frequently for certain processes or where particular toxic substances are used). The fourteen month cycle allows for seasonal variations in the performance of the equipment, but this is a maximum, not a minimum, interval between tests. Records of all tests should be kept for at least five years.
The Health and Safety Executive provides guidance for both employers and employees: