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December 23, 2008

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Local Exhaust Ventilation (LEV) system guidance

The use of local exhaust ventilation (LEV) systems is a common and effective way of controlling contamination of workplaces by hazardous dusts, fumes and vapours. However, many systems used by employers are not designed, installed, or maintained properly, which has prompted the HSE to issue a new set of information solutions, as John McAlinden explains.

Every year, thousands of workers contract occupational asthma and other lung diseases because they breathe in too much dust, fume, or other airborne contaminants at work, often because exposure control measures do not work well enough. Most industries are affected, including woodworking (both in conventional woodworking shops and on construction sites), welding, paint-spraying, stonemasonry, engineering, and foundries.

One of the most common ways of controlling exposure to airborne contaminants and

reducing respiratory risks is via local exhaust ventilation (LEV), which has the biggest potential for making a positive impact on occupational health. In terms of delivering adequate exposure control with LEV the law is clear, and requires that:

where exposure to hazardous substances (including airborne contaminants) cannot be prevented, then it must be adequately controlled; and

so far as is reasonable and practicable, exposure shall be adequately controlled by means other than personal protective equipment (PPE).

However, many LEV systems are not designed, installed, used, maintained, or tested properly. Various HSE research suggests that around 100,000 businesses use LEV to control respiratory risks for up to 2.6 million workers, but only 40 per cent have their LEV systems tested. Furthermore, suppliers of LEV goods and services often fail to provide systems that are ‘fit for purpose’, and many businesses are over-optimistic about LEV capabilities, leaving them unaware of the actual exposure risk.

Consequently, the HSE consulted with relevant professional institutions and industry employers and employees to establish how the regulator and industry stakeholders might bring about the better design, supply, use, maintenance and test of LEV to secure adequate control.

A consensus was reached that a range of new tools was needed to tackle the problem of inadequate exposure control of airborne contaminants caused by ‘not fit for purpose’ LEV systems. The new tools and approaches developed to date are as follows:

New guidance

New, better-targeted HSE guidance on LEV was produced in partnership with external stakeholders, comprising separate publications for:

designers and suppliers of LEV goods and services — Controlling airborne contaminants at work,1 and HSG258 (with a DVD) Everyone needs to breathe;2

employers who buy and use LEV systems — Clearing the air: A simple guide to buying and using LEV;3 and

employees who rely on LEV systems to protect their health — Time to clear the air! A workers’ pocket guide to LEV.4

The long-term aim of the new guidance is to influence LEV designers and suppliers to provide better LEV, and to help employers specify and purchase systems that are fit for purpose. In the shorter term, the new guidance should encourage users to properly use and maintain the LEV they already have, and to comply with the law.

Innovative training

The changes and practical approaches used in the new guidance are so significant that a new one-day training package has been introduced for the HSE’s own inspectors, as well as external training providers. The new package contains innovative training material and teaching methods, with eye-catching illustrative diagrams, stills, and video clips.

An award-winning, working LEV model5 is used to demonstrate the key design features and correct use of an LEV system. It helps explain why LEV systems fail to control exposure, and how they can be improved. The course is hands-on and includes practical sessions, using efficacy assessment tools and realistic and challenging syndicate exercises.

Trainers and advisors (including suppliers of LEV goods and services) have been invited to attend the course, where they will receive the new training materials free of charge, subject to terms and conditions.6 The priority groups HSE targeted were:

specialist LEV trainers and advisors;

LEV designers and suppliers who also provide training;

employer organisations with specialist trainers who provide training; and

employee representative trainers who provide training.

Professional competence

Stakeholder consultation also identified the professional competence of suppliers of LEV goods and services as another area of concern. Traditionally, LEV has been dealt with as a minor component of wider-ranging courses in heating and ventilation. The British Occupational Hygiene Society (BOHS) has now put in place new HSE-recognised curricula for vocational qualifications in LEV system test (P601) and LEV system design (P602).7 A one-day LEV awareness course to provide attendees with basic knowledge of the requirements and use of LEV systems is also available.

LEV website

A new website — — has been launched to complement the new guidance and training packages. Although the site is still under development visitors can already freely download the new guidance for employers and employees.

Also available for free viewing are illustrative video clips, each one referenced in Controlling airborne contaminants at work and showing how airborne contaminants can be generated by a variety of industry processes and sources. Samples of commissioning and thorough examination and test forms are also available to download.

Future plans for the website include:

the development of key messages;

case studies providing examples of successful control using LEV;

site-user feedback;

listings of relevant events, including training; and

video illustration of key LEV hood design and application factors.

The future

The input of stakeholders is vital to the application and further development of the HSE’s guidance. The regulator is therefore encouraging suppliers, employers and employees to access it and improve their LEV knowledge, so that systems in all workplaces will be fit for purpose and provide adequate control of airborne hazardous substances.

To share information on solutions that have worked well — and those that have not — e-mail [email protected]


1 HSE (2008): Controlling airborne contaminants at work (HSG258), ISBN 9780717662982, price £12.50 from HSE Books

2 HSE (2008): Everyone needs to breathe (HSG258) plus DVD, price £22.50 from HSE Books

3 HSE (2008): Clearing the air: A simple guide to buying and using LEV (INDG408) — free publication from HSE Books

4 HSE (2008): Time to clear the air! A workers’ pocket guide to LEV (INDG409), free publication from HSE Books

5 The HSE’s LEV model was highly commended in the 2008 BSIF Product Innovation Awards, presented at the Safety & Health Expo at the NEC last May

6 Further details are available from the HSL Training Unit, tel: 01298 218806 or e-mail [email protected]

7 Both courses are now available from training providers, and further details can be obtained directly from BOHS at

8 To find out more, contact any of the following: James Wheeler at [email protected]; Mark Piney at [email protected]; or John McAlinden at [email protected]

John McAlinden is a Principal Specialist Inspector with the HSE.


Approaches to managing the risks associated Musculoskeletal disorders

In this episode of the Safety & Health Podcast, we hear from Matt Birtles, Principal Ergonomics Consultant at HSE’s Science and Research Centre, about the different approaches to managing the risks associated with Musculoskeletal disorders.

Matt, an ergonomics and human factors expert, shares his thoughts on why MSDs are important, the various prevalent rates across the UK, what you can do within your own organisation and the Risk Management process surrounding MSD’s.

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