Devon & Dorset Building Management Limited

Legionnaires’ Disease

The Control of Legionella Bacteria in Water Systems

 The Law

Duties under the Health & Safety at Work Act extend to risks from legionella bacteria which may arise from work activities. The Management of Health & Safety at Work Regulations provide a broad framework for controlling health and safety at work. As well as requiring risk assessments, they also require employers to have access to competent help in applying the provisions of health and safety law.

By virtue of section 16(4) of the HSWA and with consent of the Secretary of State for the Environment, the Health & Safety Commission on 23^rd November 1999 approved the Code of Practice entitled “Legionnaires’ disease: the control of legionella bacteria in water systems”, this gives practical guidance with respect to sections 2, 3, 4 and 6 of the HSWA and regulations 6, 7, 8, 9 and 12 of the Control of Substances Hazardous to Health Regulations 1999.

Controllers of Premises Duties 

To  comply  with  their  legal  duties,  employers  and  those  with  responsibility  for the control  of  premises  should: 

1. Identify and assess sources of risk – this includes checking whether conditions are present which will encourage bacteria to multiply and be ingested in away as to place people at risk.

2. Prepare a scheme for preventing or controlling the risk.

3. Implement, manage and monitor precautions – if control measures are to remain effective, then regular monitoring of the control systems and the control measures is essential. Monitoring by sampling of general bacteria numbers can indicate whether microbiological control is being achieved.

4. Keep records of the precautions.

5. Appoint a person to be managerially responsible.

6. Provide information, instruction and training for employees.

General information about Legionellosis 

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 were 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. Patients 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 effectively 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 cases. This rate can be higher in a more susceptible population; for example, immunosuppressed patients or those with other underlying disease. Certain groups of people are known to be at higher 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.