LEV – Local Exhaust Ventilation

What is LEV?

 LEV is an engineering control used to reduce the risk of inhalation of substances hazardous to health in a workplace, such as dust, gas, mist, fume or vapour.

Typically, these substances may cause respiratory diseases such as occupational asthma, cancer and chronic obstructive pulmonary disease (COPD).

LEV systems perform an essential function to protect health. They must be properly designed, installed, commissioned, tested and maintained to be effective. It is essential that employers use competent LEV engineers.

Further information is available:

at the HSE LEV website

by viewing HSE publication Controlling airborne contaminants at work: A guide to local exhaust ventilation

You have assessed the work environment by air monitoring and decided that LEV is required. It is your responsibility to ensure that the LEV provider selected is competent to do so and will install a LEV system suitable for your needs.

An example of this not being done is; LEV service provider enforcement case

At a bakery inspection, HSE inspectors identified that the recently-installed LEV systems intended to control flour dust exposure at mixers and dough brakes were ineffective.

Flour dust and some of the enzymes and improvers used in bakeries are respiratory sensitisers that can cause occupational asthma and therefore need to be controlled to As Low As Reasonably Practicable (ALARP). An investigation into the suppliers of the LEV systems determined that the capture hood designs for the installed systems were substandard when compared to existing established effective designs for this sector.

This resulted in inadequate control of exposure for workers to flour dust.

A Prohibition Notice was served on the LEV suppliers to prevent them supplying systems to control flour dust at mixers and dough brakes in bakeries, until such time as they had complied with the requirements of the enforcement notice schedule.

Employers are urged to ensure that when they appoint LEV service providers, they make sure that the service provider is qualified and suitable. It is not uncommon for employers to spend a lot for advice that doesn’t help them comply with health and safety law, so it pays to source good quality advice.

Employers should ensure that service providers:

have evidence of relevant training and knowledge, such as formal qualifications or practical experience of providing advice in your industry or area of work; and are adequately insured

HSE has 7 key messages for employers when purchasing LEV:

  • Work out which jobs and activities cause exposure
  • Write down what the LEV needs to do – get a reputable supplier to advise you.
  • Get the right type of LEV to control exposure
  • Involve your employees in LEV design or selection
  • Make sure the LEV is installed properly and works effectively
  • Make sure the LEV has airflow indicators (or equivalent)
  • Make sure the supplier provides a User Manual and Log Book (or equivalents)


HSE key messages when using LEV:

  • Manage the checking and maintaining of the LEV system
  • Train employees to use the LEV properly (ask supplier for help)
  • Follow instructions in the User Manual (or equivalent)
  • Fill in the Log Book and get repairs done
  • Get the LEV thoroughly examined and tested ‘annually’
  • Use the thorough examination report as an ‘audit’. Improve if necessary