GET A QUOTE Click here


What is LEV?

LEV stands for Local Exhaust Ventilation.


Why do we need LEV?

LEV is required to contain substances hazardous to our health like gas, mists, vapour, fumes and fine powders given off by processes which are toxic to our respiratory system.

As employers and employees we have a duty of care to each other under The Health and Safety at Work Act (HASAWA) 1974 and the Control Of Substances Hazardous to Health Regulations (COSHH) to control the release of such substances.

We also have to ensure that we protect others who could be affected by what we do.

The Health and Safety Executive (HSE) has produced a document called the HSG258 which is the approved code of practice for dealing with COSHH substances and has set the requirements for testing and recording the effectiveness of the control methods.


Testing.Air Source Heat Pump Installer in Winchester.

The HSE require your LEV systems to be tested at least once every 14 months to maintain performance and keep people safe. We understand the HSE requirements and ensure you are compliant with them by using properly qualified engineers to test your systems. The test is called the Thorough Examination and Testing (TExT) of LEV Systems. The competent person must hold a recognised qualification such as British Occupational Hygiene (BoHS) P601 to be recognised as an approved examiner by the HSE.

Our service is designed to provide ongoing assistance with existing LEV systems. However, Air Improve have the back up and support of the LEV industry leaders in order to deliver solutions to improve failed systems or design new LEV systems to meet changing requirements. We can also provide experts to conduct environmental monitoring to prove whether your LEV is working correctly and to determine whether your employees are working within your Workplace Exposure Limits (WELs).

Notably, commercial insurance companies are asking for proof that the LEV systems are operating. Some insurers are providing their own in-house testing, which is often just an airflow test and if you read the small print the onus is put back onto the employer and employee to ensure these systems are operating correctly. Therefore the insurer’s tests are not adequate to fulfil the requirements of the HSG258.

For your peace-of-mind, and knowing that you are doing the best you can to protect others from exposure to COSHH substances, we recommend you seek expert advice.

We are here to help.


What the Thorough Examination and Test of LEV Systems involves

Every site is different, so we insist on an initial appraisal visit to determine the extent of your systems, what they are used for, what Health and Safety requirements are required to work and access the LEV on your site. We would gather data on previous tests and commissioning records for comparison of results and your Risk Assessments for handling the substances involved in your processes.

System drawings and service records would also be useful but are not essential. We would also be able to tell from this visit whether the LEV was controlling the hazardous substance effectively and whether it was being used correctly. This would save time and money for you by identifying systems that could fail the examination so you can plan to put time and funds into redesigning your LEV.

Often we are the bearers of bad news, as previous tests might have been undertaken by inexperienced engineers, unfamiliar with the HSE’s requirements of HSG258 who have passed systems based on proving airflow rather than the effectiveness of substance control.

Ultimately it is your responsibility as employer to ensure that the LEV is fit for purpose and operated correctly. A common practice is to issue the employees with Respiratory Protective Equipment (RPE). This may be the wrong type, or not face-fitted and which can add additional strain to the heart and respiratory systems. This could then reduce the employees productivity as they are required to take regular breaks. Please refer to Guidance RPE HSG53.

The other issue to bear in mind is that the RPE will protect the individual but what about the collective protection of others in the same area, or nearby. RPE really is a temporary measure and can be used with LEV but the whole point of LEV is that it controls the substance and prevents it from escaping and doing harm.

Our comprehensive understanding of the HSE’s approach will mean you are in full compliance with the latest standards and regulations.


How much does it cost to have an LEV Thorough Examination and Test?

Our price will vary depending on the complexity of the system and the information that is available. Sufficient time would be required to prepare and produce the report, which will be undertaken off-site.

We will quote a site specific, fixed price for consideration. This will include the initial appraisal visit, preparation of a method statement and risk assessments, test visit and reporting. Often we have found that there are multiple LEV systems on site which can make the visit more cost effective, also subsequent visits can be discounted as the preparation time for producing the reports is reduced. On completion of the site examination the LEV owner will know whether the LEV has passed or failed before the examiner leaves site.

During the initial survey visit the examiner will discuss with the LEV owner how they want the information to be relayed as we can appreciate this can be very sensitive, obviously when the LEV has failed the test.

Please note that the test is no guarantee of a pass, and like a vehicle MOT requires the system to be maintained and used effectively.


The LEV test:

Once the initial appraisal is complete and we are engaged in conducting the TExT we will generally follow the following format:-


Visual examination and measurement of technical performance to include:-

  • General assessment of whether the workplace has evidence of substance contamination
  • System setup and correct installation and operation
  • Assessing damage, wear and tear
  • Checking that pressure gauges and other display devices function properly
  • Examining the fan, including speed and direction of rotation
  • Checking the filter material to ensure it is the correct filter for the purpose and the fit is good
  • Testing airflow alarms and air proving protection systems
  • Assessing internal ducts, to determine duct velocities and levels of contamination if possible
  • Checking external ducts are the correct height and have the correct exhaust terminals and whether there is any possibility of secondary contamination
  • Testing the air cleaning device is working effectively, if present
  • Analysing the makeup air supply
  • Measuring air temperature
  • Comparing volume flow rate against the design specification
  • Taking velocity readings at hood faces, branch ducts and main ducts if accessible
  • Measuring static pressure in the ducting, through the air cleaner and fan and behind each hood

Smoke testing will be used as a suitable way of determining the operator’s exposure to the substance, particularly when observing the behaviour of gaseous substances.

The smoke test maybe used in conjunction with a Tindall beam to illuminate the particulates given off by a process e.g. grinding, to see whether the substance is being controlled and not entering the operator’s ‘breathing zone’.


The Report

Each LEV system will have its own independently identified report. This will include the system specifics, photographs, video files, system schematics, test information, and summary. This report will be HSE compliant, meeting the requirements of the BoHS. This document is a legal document and has to be stored for 5 years under the COSSH LEV requirements.

Following on from the report there will be immediate actions points and routine procedures which may need to be put in place to ensure that the systems are used and maintained correctly. If the LEV is not operating correctly then it will ‘FAIL’ the examination and the process must stop until suitable control measures have been put in place.


After the remedial action the system has to be re-tested and then be passed by an examiner.