HSE Local Exhaust Ventilation (LEV) ebulletin
To protect your health LEV in the workplace should be effectively carrying away the harmful dust, mist, fumes or gases at the point where they are generated.
In order for LEV to be effective it needs to be:
- the right type for the job
- installed properly and be commissioned in the first place
- used properly
- checked regularly and maintained throughout the year
- tested and examined thoroughly by a competent person at least once every year
- checked if moved – does it still work effectively?
Before you begin using LEV it is important to check that it is working correctly. One way of doing this is to complete a daily check of the following:
- does the airflow indicator show the LEV is working properly?
- is it taking away all the harmful dust, mist, fumes and gas? (some of these may be invisible)
- is the LEV close enough to the source of the dust, mist, fume or gases so it can do its job properly?
- are there any signs it is not working properly, like smells or settled dust near the LEV hood?
- are there any unusual noises or vibration coming from it?
- has it been thoroughly examined and tested, with a ‘tested’ label that is within date?
- have you told your supervisor about anything you think may be wrong?
Capture Hoods and how to work safely with them
The most common type of LEV hood is called a capture hood.
This is where the process, source and contaminant cloud are outside the hood and the hood has to generate sufficient airflow at and around the source to ‘capture’ and draw in the contaminant-laden air.
Your employer must provide you with information and instruction on how to use any LEV correctly. Each LEV system should have a user manual that details how to use the system safely.
If the LEV has a positionable capture hood, this should include information on how close the hood needs to be in order for it to effectively ‘capture’ or control the harmful substances that are generated.
Positioning the hood correctly is very important, because if this is not right, then the LEV may not be as effective as you think.
Employees should be provided with sufficient information to know the size and shape of the capture zone for the capture hood, so that they can work within it and position the hood correctly.
For more guidance and advice, you can download the following publications from the HSE website: