Legionella & Legionnaires’ Disease

Legionnaires’ disease is a potentially fatal form of pneumonia which occurs as a result of infections caused by the legionellaceae family of bacteria. It principally affects those who are susceptible because of age, illness, immunosuppression or smoking, resulting in around 250 identified cases a year. Legionnaires disease is contracted by inhaling small droplets of water suspended in air which contain the legionella bacterium.

Legionnaires bacteria occurs naturally in environmental sources like surface water and soils but can also proliferate within man-made environments such as cooling towers, hot and cold distribution systems, water plants, humidifiers, evaporative condensers, whirlpool spas and air washers.

Proliferation of the bacteria typically occurs between 20°C – 45°C and is assisted by the presence of suitable nutrients present in dirt, sludge and scale as well as conditions of poor water flow, stagnation or where dead legs occur in water systems.

Employers are required to control the risk of exposure to legionella bacteria in accordance with Health and Safety at Work etc Act 1974, Control of Substances Hazardous to Health Regulations. This is achieved by following the Approved Code of Practice L8 The Control of Legionella (Bacteria in Water Systems) HSG274 part 2 and guidance on compliance with the relevant parts of the Management of Health and Safety at Work Regulations 1999. In general, these require the employer to conduct the following:

• Identification & assessment of the risk
• Prevention or minimisation of risk from exposure to Legionella
• Systems for the management, selection, training and competence of personnel
• Record keeping of maintenance, cleaning and disinfection