HSG258 explained: the HSE guide to LEV

What HSG258 is

The full title is Controlling airborne contaminants at work: A guide to local exhaust ventilation (LEV). HSG258 is its HSE series code. The third edition was published in 2017 and is available as a free PDF. It explains the principles of selecting, designing, commissioning and testing effective extraction.

HSE wrote it for employers who already use LEV or plan to install it. Suppliers, managers, trade union representatives and employee safety representatives can also use the guidance. The third edition contains minor changes and clarifications. Its advice is broadly unchanged from the previous edition.

Is HSG258 the law?

No. HSG258 is guidance. Unless specifically stated, following it is not compulsory, and you may take other action. HSE says following its guidance will normally be enough to comply with the law. Inspectors may refer to it when checking compliance.

The legal duties come from COSHH regulations 7, 8 and 9. COSHH means the Control of Substances Hazardous to Health Regulations. Regulation 7 requires you to prevent exposure or adequately control it where prevention is not reasonably practicable. Regulation 8 requires reasonable steps to ensure controls are used properly. Employees must use them properly and report defects. Regulation 9 covers maintenance, examination, testing and records.

L5 contains the COSHH Approved Code of Practice (ACOP) and guidance. The ACOP has greater legal weight in Great Britain's courts than guidance alone. In a prosecution, failing to follow relevant Code provisions means you must show another way you complied with the law. Otherwise, the court will find you at fault. L5 points employers to HSG258 for guidance on examination and testing.

The COSHH 2002 regulations cited here apply in England, Wales and Scotland. Northern Ireland has its own COSHH regulations, introduced in 2003.

What the ten chapters cover

The ten chapters cover responsibilities, contaminants, design, installation, documents and testing. Two appendices address legal requirements and the choice of control benchmarks and requirements.

What HSG258 asks employers to keep

Request a user manual and logbook from your supplier. Keep the commissioning report too. Commissioning proves that the system can adequately control exposure. Its report and the manual provide the basis for later statutory tests.

The commissioning report should describe the system and identify its test points. It should include the performance specification, pressure and velocity results, calculations and the findings of the checks. It should also explain how operators need to work for effective extraction. Air sampling results belong in it where necessary.

Your manual should explain operation, maintenance, available spares and things that can go wrong. It should include a diagram naming the main components. HSE favours simple starting instructions alongside detailed information for maintenance and service staff. The detailed information should include signs of failure, check schedules and test benchmarks. Instructions should be in English.

Use the logbook to record checks, maintenance, replacement parts and repairs. Record who checked the system and whether people were using it correctly. Include schedules and identified daily, weekly and monthly checks for the system's components.

Keep examination and test reports for at least five years, with a copy available at the workplace. COSHH also requires records of repairs resulting from those examinations and tests to be kept for at least five years. Retain information showing the installed system provides adequate protection for the life of the equipment.

If the manual or logbook is missing, approach the manufacturer first. If that fails, ask an LEV specialist to help prepare suitable documents. Where no documents are available, you can ask the examiner for a commissioning report as an additional service. Agree that work and its cost with the examiner.

What HSG258 says about the thorough examination and test

The test checks whether your LEV can still perform as designed and help control exposure. HSG258 describes three stages: a visual and structural examination, a review of technical performance, and an assessment of control effectiveness.

Give the examiner the commissioning report, manual, logbook and previous test report. Include relevant air sampling records and information on how operators use the extraction. Confirm whether the system, workplace layout or process has changed since the last test.

If the system is unsafe, the examination should stop until repairs restore its original performance. Ask the examiner to label each tested hood. A fail label identifies a hood that has not passed. HSG258 describes red labels for inadequate airflow or a hood failing to contain or capture the contaminant cloud.

The examiner should provide a prioritised action list. L5 says you should address critical defects immediately to ensure adequate control. The report should identify the employer, system location, process and hazardous substances. It should give the current and previous test dates. It should name the examiner, their job title and employer, and include their signature. Minor adjustments, repairs made during the examination and critical defects should also be recorded.

Arrange the statutory examination and test at least once every 14 months. Schedule 4 sets shorter intervals for specified processes. HSG258 advises more frequent testing where wear could reduce effectiveness between examinations.

What HSG258 does not cover

Paragraph 9 excludes several specialist topics. It does not cover biological agents, radioactive substances or pharmaceutical containment. It also excludes confined spaces and air blowers, refuges and cleaning systems. Refuges here means clean rooms within contaminated environments.