Assessing and Preventing the Risk of Legionnaires Disease
Legionnaires disease is a bacteria that causes a respiratory disease affecting certain types of people more strongly than others. It can be fatal to those with respiratory problems, the elderly or people who have autoimmune deficiency diseases. The bacteria can also cause many other serious health risks that may not be fatal, or cause permanent damage, but still have serious affects.
Legionellosis is the term used to describe all infections caused by the legionella bacterium. The bacterium is naturally occurring, and can be found in all water sources, ie streams, reservoirs etc, albeit in low numbers.
Once the bacteria have infiltrated a man made water system, it can easily colonize the system, particularly if it is not maintained and operated in line with the minimum guidelines set by ACOP L8. This document has been in existence since 1999 (current edition 2001), superseding the previous HSG(70). The full title is ‘Legionnaires Disease – The control of Legionella bacteria in water systems’, and ACOP stands for ‘Approved code of practice’. This book carries special legal status – failure to comply will result in prosecution under COSHH regulations and the Health and Safety at Work act.
All man made water systems are at risk, and should be assessed (risk assessment) for legionella proliferation potential. Again, this is legislation within COSHH. From a single mains fed tap, to major office installations, to elaborate cooling equipment, control of legionella is vital. Local environmental health officers (EHO) have taken Legionella more seriously in recent years, and as part of their audits on commercial premises, are now asking for sight of the Legionella risk assessment. Improvement notices are issued, failure to comply with these notices normally results in the premises being forcibly closed until procedures are put in place.
NB, a person does not necessarily have to contract legionnaires disease, failure to comply with these acts is enough to warrant prosecution. Unlimited fines are imposed, both at a corporate and personal level, and individual persons ultimately responsible can, and have been given prison terms. (in many cases this defaults to the managing director, however if he has deputized a responsible person, it can be them). Can your business afford say 1 month closure?
The bacteria is contracted through inhaling contaminated water droplets, which are generated as a fine spray or mist. Any plant which is capable of creating this fine spray or mist (showers, cooling plant, spa baths, spray taps, fountains, car washes, pressure washers dental equipment, process machinery, etc etc) presents an increased risk to public health. How many of these are on your premises currently? Don’t know? (Legionella risk assessment!). How many older employees (40+) have had time off work in the past year with severe influenza/pneumonia type symptoms? Legionella infection is under reported due to the fact the symptoms are so alike to pneumonia/influenza.
Design and Construction
Each site needs to keep a detailed log of its system that includes the following information:
1. Functional diagram of the complete water system that includes any changes or modifications carried out to the system since its installation.
2. Record of the monthly checks that are carried out on the system with complete details of any repairs or maintenance. This includes cleanings and disinfections (chlorination).
3. Record of the annual inspections that must be done
4. Copies of all water sampling that is carried out.
5. Management pathway and responsibility structure, detailing the personnel responsible for
maintaining the system, as well as the escalation procedures.
6. Records of training.
Systems that are new should be completely cleaned and sanitized at least one week before the building it to be occupied. Only materials and fittings that are approved by WRAS should be used in its construction and repair. When repairs are carried out, any parts that have been added need to be cleaned and sanitized as well as the pipework they will be connected to. Tanks used for storage need to be clearly labelled to assist identification. Permanent labels need to be placed on all hot and cold services in a place that is easily visible.
Operation and Maintenance
Weekly flushing must be carried out on underused outlets.
Cold water needs to be maintained at a temperature less than 20
Hot water in a calorifer should be stored at a minimum temperature of 60
Unblended hot water at the outlets should reach 50
These are the basic control requirements, which are obviously not extensive. A full Legionella risk assessment would be required to design an appropriate control regime for your premises.
oC. oC. oC within one minute of running.
Does your system include water tanks, calorifiers, electric water heaters, showers, cistern type heaters, etc?
Water sampling should be carried out by highly trained and competent staff or outside specialists.
Interpreting bacteriological results from water sampling requires a suitable level of competence.
What do you do if results show a low, medium or high level of bacteria?
Background to legionnaires disease and legislation
Legionnaires Disease was first identified following a large outbreak of pneumonia among people who attended an American Legion Convention in Philadelphia in 1976. A previously unrecognised bacterium was isolated from lung tissue samples which was subsequently named Legionella pneumophila.
It is normally contracted by inhaling Legionella bacteria, either in tiny droplets of water (aerosols), or in droplet nuclei (the particles left after the water has evaporated) contaminated with legionella, deep into the lungs. There is evidence that the disease may also be contracted by inhaling legionella bacteria following ingestion of contaminated water by susceptible individuals. Person to person spread of the disease has not been documented. Initial symptoms of Legionnaires’ disease include high fever, chills, headache and muscle pain. Patient may develop a dry cough and most suffer difficulty with breathing. About one third of patients infected also develop diarrhoea or vomiting and about half become confused or delirious. Legionnaires’ disease can be treated affectively with appropriate antibiotics.
The incubation period is between 2-10 days (usually 3-6 days). Not everyone exposed will develop symptoms of the disease and those that do not develop the ‘full blown’ disease may only present with a mild flu-like infection
Infection with legionella bacteria can be fatal in approximately 12% of reported case. This rate can be higher in a more susceptible population; for example, immunosuppressed patients or those with underlying disease. Certain groups of people are known to be higher at risk of contracting Legionnaires’ disease; for example, men appear more susceptible than women, as do those over 45 years of age, smokers, alcoholics, diabetics and those with cancer or chronic respiratory or kidney disease.
On average, there are approximately 200-250 reported cases with approximately 12% fatalities.
The Health and Safety Commission announced in April 1989 its intention to take statutory action to strengthen existing legislation and guidance on the control of Legionnaire’s disease. The Approved Code of Practice (ACOP) ‘The prevention or control of Legionellosis (including legionnaires’ disease)’associated with the Health and Safety Executive guideline HS(G)70 – The control of Legionellosis including legionnaires Disease was approved by the secretary of State for Employment on the April 10, 1991 and became effective on January 15, 1992. It has since been amended in 1995 to include where applicable, references to the COSHH regulations (Rev. 1994) and place greater emphasis on the need for regular Risk Assessment reviews.
HS(G)70 itself has since been revised and published as a second addition in 1993 in order to cover the development of new control technologies and practical considerations arising after publication of the first edition.
It has now been replaced by the updated document L8 which came into effect on the 8th of January 2001.
The ACOP applies whenever water is stored or used in a way that may create a reasonably foreseeable risk of Legionellosis. In particular it applies to the following plant:
Cooling tower systems;
Hot and cold water systems non-domestic premises;
Hot and cold water systems where the occupants are particularly susceptible. (i.e. Health/Care Premises);
Humidifiers and air washers, spa baths and pools;
Other plant and systems containing water which is likely to exceed 20OC and which may release a spray or aerosol (i.e. a cloud of droplets and/or droplet nuclei) during operation or when being maintained;
Whilst this is not an exhaustive list, it does identify those systems which are most likely to cause infection. Consideration should also be given to other systems, which can release spray or aerosol during operation, maintenance and testing.
The scope of a Legionellosis Risk Assessment is defined in the A.C.O.P. L.8 paragraphs 18-38
Contact us today to discuss how we can help your organisation comply – with minimal fuss