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Legionella: Other Risk Systems - Overview of guidance on HSG 274 Pt3

The formal system of Legionella control in the UK currently comprises the Health and Safety Executive’s ACOP L8 (4th edition) and HSG 274 Legionella guidance, which is split into three parts:

  • Part 1  - The control of Legionella bacteria in evaporative cooling systems
  • Part 2 – the control of Legionella bacteria in domestic hot and cold water systems
  • Part 3 – The control of Legionella bacteria in other risk systems

What are other risk systems?

In addition to evaporative cooling systems and hot and cold water systems there are other risk systems that may produce water droplets (aerosols) and pose a foreseeable risk of exposure to Legionella.

Many of these systems operate at or above ambient temperature, or are prone to thermal gain during operation. This may be seasonal for some – for example, irrigation systems that operate outdoors so may use water at temperatures that fall within the recognised temperature range for legionella bacteria growth.

All these systems have the capacity to generate aerosols during operation and some, like powered dental equipment and respiratory therapy nebulisers, may dispense them directly into an individual’s breathing zone.

Examples of these types of systems include, but are not limited to:

  • Ultrasonic humidifiers/foggers
  • Misting devices used for humidifying vegetables, meat and other food products
  • Spray humidifiers
  • Air washers, wet scrubbers, particle and trivial gas scrubbers
  • Water softeners
  • Emergency showers, eyebaths and face wash fountains
  • Sprinkler and hose reel systems
  • Spa pools
  • Whirlpool baths
  • Horticultural misting systems
  • Vehicle washers including automatic washers for cars, buses, lorries and railway rolling stock
  • Powered dental equipment
  • Fountains and decorative water features including those on display for sale
  • Non-disposable nebulisers used for respiratory therapy
  • Industrial effluent treatment plants
  • Irrigation systems
  • Fire, dust and odour suppression systems
  • Paint spray preparation equipment
  • Tunnel pasteurisers and similar equipment

Risk Assessment

There is a duty to carry out a risk assessment to decide whether further actions are needed, to maintain records of all maintenance carried out, and monitor results. These systems and any others found to present a risk need to be adequately controlled and will often require a combination of measures, such as regular maintenance to ensure the system is kept clean, regular disinfection and ongoing monitoring where appropriate.

If you’re unsure if your water system carries a risk, or would like further expert advice on this, contact Brodex.

For further information on Legionella risk assessment go to:

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