Legionnaires Disease
In 1976 several people attending an American Legion Convention in Philadelphia (USA) became ill with pneumonia. The cause of the illness was discovered to be a previously unknown bacterium which was subsequently named Legionella pneumophila. There are two main forms of the disease, the more serious and potentially fatal Legionnaires Disease and a milder form known as Pontiac Fever.
There are no recorded cases of the disease being spread from person to person. It may be contracted by inhaling droplets of water or aerosols contaminated with legionella bacteria deep into the lungs. Certain groups of people are known to be at higher risk of contracting Legionnaires' disease e.g. men more than women,those over 45 years of age, smokers, alcoholics, diabetics and those with cancer and chronic respiratory or kidney disease.
Legionella and related bacteria are common and can be found in natural water sources and in hot and cold water systems in various working environments. Legionella can survive in temperature ranges between 6 o C and 60 o C with temperatures between 20 o C and 45 o C particularly favouring growth of the bacteria. Temperatures also influence virulence: a strain of legionella held at 37 o C has greater virulence than when held below 25 o C. It is therefore vitally important that a suitable and sufficient risk assessment is carried out on all appropriate water systems identifying all areas where the risk of survival or proliferation of the bacteria may occur including e.g. shower heads, water storage tanks, dead legs of pipework and calorifiers.
A report published by Health Protection Scotland (Legionellosis in Scotland 2004-2006) showed that in 2006 there were 42 reported cases of the disease 3 of which resulted in death.
Legal Requirements
Those who own, operate or occupy business premises (The Duty Holders) have a legal responsibility to control the risks of exposure from this pathogen under health and safety at work legislation.
The duty holders of premises that have any water cooling towers or evaporative condensers must register them with their Local Authority.
A registration form is available to download by clicking on the links. Once details have been entered, the completed form should be posted to the Health and Safety (Enforcement) Section, The Environment Service, Perth and Kinross Council, Pullar House, 35 Kinnoull Street, Perth PH1 5GD.
Duty holders of premises with hot and cold water systems (e.g. hotels, Bed and Breakfast establishments,swimming pools,leisure facilities,caravan parks etc)also have the same duty to control legionella bacteria within those systems. A competent person is required to assess the risks of legionella and prepare and implement a management system to control the potential for growth of the bacteria within the system (s).Management systems must include regular monitoring and recording of hot and cold water temperatures and the implementation of regular and adequate cleaning and disinfection of showerheads and hoses.
Management Controls
As previously mentioned duty holders must ensure that the risk of exposure to legionella bacteria from potentially contaminated sources is sufficiently controlled to reduce the chances of persons contracting this disease and are specifically required to;
1) Identify and assess of risk of legionellosis from appropriate sources.
Unless there are suitably qualified and experienced in house staff, a competent person will need to be appointed to carry out or assist in the completion of this requirement.
2) Prepare a written scheme for preventing or controlling the risk.
This will include but is not limited to; procedures to control water temperatures, cleaning and disinfection of water systems, maintenance of equipment, use of appropriate materials, using suitably qualified and experienced contractors, providing information for employees etc.
3) Implement, manage and monitor precautions.
Once such a scheme has been prepared it must be implemented and managed. In order that the procedures and controls which have been put in place remain effective they must also be regularly monitored. A critical component of this monitoring is the regular microbiological examination of water samples to ensure that the bacteria is being adequatly controlled.
4) Maintain records of the precautions.
Records relating to the management system and monitoring required must be kept for at least 2 years.
5) Appoint a person to be responsible for managing the system put in place as outlined in 1-4 above.
A responsible person must be appointed to ensure that the necessary controls and procedures are implemented.
Records and microbiological checks must be regularly reviewed to ensure that the control measures put in place continue to be suitable and sufficient, and that health and safety legislation is being met.
Further information
More detailed information can be found in the HSE publication titled "Legionnaires disease-The Control of Legionella bacteria in water systems - Approved Code of Practice and Guidance" L8 (ISBN 0-7176-1772-6) which is available from HSE Books, bookshops and The Stationery Office (TSO). The external links in the right hand column of this page will take you to other sources of information on this subject.
