What is LEV Testing (Local Exhaust & Ventilation Testing)?

LEV Testing

The Health and Safety Executive released a document (HSG258) that calls all employers to ensure their LEV systems are tested, but what exactly does that mean?

LEV testing is an important part of ensuring a business is compliant with health and safety laws, and more importantly, that it’s employees are working in a safe environment. In order to save employers undue worry & to give clarity, we have written an article that aims to answer some of the most common questions regarding LEV testing.

What does LEV stand for?

LEV is an acronym for Local Exhaust Ventilation, often known as extraction or fume control.

What is an LEV system?

An LEV system is an engineering control system to reduce exposure to airborne contaminants such as dust, mist, fume, vapour or gas in the workplace. This would typically be made up of ducting, a fan, an inlet and an outlet. More often that not, your LEV system will also have a filter.

What are the principles of LEV?

The main principle of LEV is to remove contaminants from the air so that they cannot be breathed in. Properly designed LEV will collect air that contains the contaminants making sure that they are taken away from people. The air will then be cleaned (if necessary) and contaminants safely disposed of.

What is a LEV test?

Over time an LEV system’s performance will diminish due to blockages, wear, damage and leaks. The COSHH (Control of Substances Hazardous to Health) regulation 9 states:

Where the regulation is met through the use of engineering controls, the employer shall ensure that thorough examination and testing of those controls are carried out. In the case of local exhaust ventilation plant, this will be at least once every 14 months.


As an LEV system can deteriorate over time, whether it be due to filters reaching the end of their lifespan, improper use of the system, or general wear and tear. For this reason, it must be tested to investigate whether it is still maintaining airflows within HSE guidelines.

LEV Test Filter

How often should LEV be tested?

LEV regulations say that you should arrange a thorough examination and test your LEV at least every 14 months.If any modifications are made to the system (such as the layout or hood redesign), the previous report would not be valid and the system would need to be recommissioned. In some cases, an LEV test needs to be performed every six months, or even every month. This depends on the processes in place, so please speak to your LEV engineer to how often you need an LEV test.

Who should I get to complete my LEV tests?

As you are legally responsible to ensure that exposure to dust & fumes for your workforce is minimised and controlled, you need to ensure that your LEV testing company is reputable.

You should look for references or testimonials of your Local Exhaust Ventilation testing company. HSG258 says that a “competent person” should carry out the tests. We strongly feel that this person should be P601 accredited. This is a UK qualification on Thorough Examination and Testing of Local Exhaust Ventilation Systems. The company you choose should be able to demonstrate an understanding of the law & of the COSHH regulations & Approved Code of Practice.

What should the LEV testing company do?

An LEV tester will check the airflows of the ducts, check face velocities of hoods, perform smoke tests to find the maximum capture distance, perform visual inspection of the filters and system in general, and investigate the processes being used to determine if the system is used correctly.
All of this information and more will be compiled into a comprehensive LEV report, which you should keep on record for a minimum of five years.

In the event of a system being deemed unsatisfactory, a good LEV engineer will advise you of the necessary steps that need to be taken to return it to an acceptable condition.

LEV Test

Do I have to fit airflow indicators?

Airflow indicators (or LEV indicators) are recommended but are not mandatory. We have seen an increased amount of scaremongering in this regard from businesses looking to take advantage of uninformed LEV owners. Your decision to purchase airflow indicators should not be based upon this but rather on the risk of exposure, whether the operator has to set the hood airflow, whether it’s possible or practical to perform other checks and the cost to the business.

LEV Indicator

Do LEV systems have to be labelled by testers?

Yes. All hoods should be labelled when tested, clearly stating whether they have passed or failed. There is no legal requirement to label ducts, but it is advisable to do so.

What are my responsibilities as a business owner?


Your responsibilities are to ensure that your business and its systems are compliant. You should ensure that the employees that use your

LEV equipment are competent & that they have the knowledge, skills & experience necessary to do the job safely. You need to ensure that your systems are tested and that they are compliant every 14 months. Records of your LEV tests must be kept for at least 5 years. There is increased attention around LEV equipment and it is increasingly becoming an important touchstone for employee safety. It is vital that you stay compliant.

What if I have another question?

You are welcome to contact us for some practical, no-nonsense advice. We will happily help you to ensure that you have taken the steps necessary and advice you of LEV services needed in order to become or remain compliant. Please feel free to contact us.