Legionnaires Disease - H & S Guide

Two recent incidents have highlighted the need to ensure employers manage their water systems and reduce the potential for the growth of Legionella Bacteria.

The Health Protection Agency launched an investigation following the death of a male. A further two cases of Legionnaires' disease were diagnosed in the local area.

Following an unrelated incident in wales the Health and Safety Executive (HSE) is warning companies responsible for carrying out legionella surveys on water systems of the need to ensure that their work is thorough and accurate.

The warning follows the conviction of a Berkshire-based water treatment company for carrying out inadequate and misleading surveys at nursing homes in Blaenau Gwent and Powys. As a result, vulnerable residents at the homes would have been at a heightened risk of contracting legionnaires disease, a potentially fatal form of pneumonia. During 2007, the company were commissioned to carry out legionella risk assessments at Nursing Homes operated in Tredegar and Llangattock, and rated the risk as low.

A subsequent routine check of these nursing homes revealed there to be inadequate controls for legionella at these premises, and the focus moved on to the work carried out by the specialist contractor. HSE inspector Matthew Hamar said: "The nursing home operators commissioned the specialist contractort to carry out the surveys in good faith and to help them comply with their responsibilities to manage the risk posed by legionella on their premises. They were badly let down in this case".

"Elderly nursing home residents are at greater risk from the bacteria that give rise to conditions such as legionnaires disease, so it is imperative that safety critical surveys like those carried out by specialist contractors are adequate".

What is Legionairres Disease?

Legionnaires’ disease is one of a group of diseases known collectively as Legionellosis. Legionellosis is caused by the bacterium Legionella pneumophila and there are two distinct forms:

• Severe - Legionnaires' disease, a well-known potentially fatal pneumonia-like disease, and
• Mild – less severe illnesses, including Pontiac fever and Lochgoilhead fever.

Why is there concern about Legionnaires’ disease?

Legionnaires' disease can be very serious and, when outbreaks have occurred, has been known to cause death in between 5% and 30% of cases. Most cases can be treated successfully with antibiotics and healthy people usually recover from infection. Infection is caused by breathing in small droplets of water contaminated by the bacteria. The disease cannot be passed from one person to another.

Who is affected/most at risk?

Everyone is potentially susceptible to infection but some people are at higher risk e.g. those over 45 years of age, smokers and heavy drinkers, those suffering from chronic respiratory or kidney disease, and people whose immune system is impaired. Legionnaires’ disease is serious in elderly and infirm patients; pneumonia is a common cause of death in people over 70.

Where is Legionella found?

Legionella bacteria are widespread in natural sources of water including rivers, streams and ponds and may even be found in soil. Since Legionella are widespread in the environment, they may contaminate and grow in other water systems such as cooling towers, evaporative condensers and hot and cold water services. Outbreaks of Legionnaires' disease have occurred in or near large building complexes such as hotels, hospitals, offices and factories. Spa baths have also been associated with cases of infection. There is no evidence that water systems in domestic homes present a risk.

If Legionella is so widespread why aren’t there more outbreaks?

Infection is caused by people breathing in water droplets contaminated with Legionella bacteria. But for infection to occur a chain of events has to take place and fortunately this does not happen very often.

The chain includes:

• Conditions suited to the multiplication of the organism, i.e. water temperatures in the range 20°C to 45°C and the presence of sludge, scale, rust, algae and organic matter to provide nutrient;
• A means of creating breathable droplets;
• Contact with the droplets by a susceptible person.

How can the risk be reduced

Since Legionella is widespread in the environment, it cannot be prevented from entering water systems. However, the risk of an outbreak developing can be reduced by taking the following precautions:

• Hot and cold water service cisterns and pipe work should be designed so that water is not allowed to stand undisturbed for long periods;
• Cisterns should be covered to prevent the entry of dirt, debris and vermin and should be inspected periodically, cleaned and disinfected;
• Water temperatures between 20°C and 45°C should be avoided. Cold water tanks and pipes in warm spaces should be insulated. Hot water should be stored at 60°C and kept at 50°C or above in circulation. Where there is a risk of scalding, thermostatically controlled taps may be needed (e.g. in residential care homes hot water temperature must not exceed 43oC);
• Fittings and materials used in water systems must comply with water authority by-laws (certain materials e.g. leather and some rubbers and plastics support the growth of bacteria and should not be used).

Cooling Towers

• Cooling towers and their associated water systems need to be well designed, maintained and operated; the fitting of efficient drift eliminators that reduce the escape of spray is especially important;
• Systems should be cleaned and disinfected at least every six months;
• Water should be treated to prevent scale, corrosion and microbiological growth;
• Where reasonably practicable, cooling towers should be replaced with dry cooling systems.

What does the law say?

Employers and persons in control of premises (e.g. a landlord) have a general duty under the Health and Safety at Work Act 1974 to ensure the health and safety of any person that could be affected by their activities, which includes preventing illness from Legionella bacteria. The Control of Substances Hazardous to Health Regulations 2002 (COSHH), as amended, impose a specific duty to eliminate or reduce to the lowest reasonably practicable level risks to health from hazardous substances (the definition of a hazardous substance includes bacteria arising in connection with work activities). Therefore, an employer or a person in control of the premises must:

• Identify and assess sources of risk;
• Prepare a scheme (or course of action) for preventing or controlling the risk;
• Implement and manage the scheme, which includes appointing a person referred to as the ‘responsible person’ to oversee the scheme; and
• Keep records and check that what has been done is effective.

Organisations that will have a duty to prevent risks from Legionella include:

• Local authorities;
• Universities;
• Housing associations, including housing companies;
• Charities;
• Hostels;
• Owners of residential care homes;
• Landlords in the private renting sector;
• Managing agents;
• Hoteliers and B&B, guest house and holiday camp owners;
• Operators of sports and leisure centres;
• Caravan and camping site owners, including fixed caravan sites; and
• Industries where water is circulated for cooling processes;

Since November 1992 persons in control of premises containing wet cooling towers and/or evaporative condensers have had a duty under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992 to notify their local authority Environmental Health Department that they operate such equipment. Notification will help Environmental Health Officers and others to act quickly if an outbreak occurs. Notification forms are available from Environmental Health Departments.

Risk Assessment

The current version of the NorthgateArinso Employer Services Risk Assessment Manual contains a pro forma that can be used to record a Legionella risk assessment. The Health and Safety Executive (HSE) has produced Audit Checklists that can be used to audit water systems (see item 6 in “Further Advice” at the end of this Guidance Note).

If there is an outbreak, what action is taken?

As soon as an outbreak is suspected a team of specialists, including staff from the local authority Environmental Health Department and the Public Health Laboratory Service, mount an investigation to:

• Identify the source;
• Identify those people likely to be affected;
• Insure the contaminated water system is treated as quickly as possible.