Legionella is classified as a Group 2 Hazardous Biological Agent (HBA) in terms of the HBA Regulations, and thus requires exposure management.
Legionnaires’ disease was first identified after a large outbreak of pneumonia among people who attended an American Legion Convention in Philadelphia, USA in 1976 in which 34 people of the 221 cases died.
A previously unrecognised bacterium was isolated from lung tissue samples, and was subsequently named Legionella pneumophila.
Legionella is widespread in nature as bacteria found at low levels in rivers, lakes and groundwater. They may also be found in water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools.
People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the bacteria. Any water system, with the right environmental conditions, could be a source for legionella bacteria growth.
There is a reasonably foreseeable legionella risk if your water system:
- has a water temperature between 20–45°C
- creates and/or spreads breathable droplets, eg. aerosol created by a cooling tower, or water outlets
- stores and/or re-circulates water
- is likely to contain a source of nutrients for the organism to grow, eg. rust, sludge, scale, organic matter or biofilms
Other known systems which could encourage the spread of Legionella are humidifiers, air washers, emergency showers and indoor ornamental fountains.
The risk of contracting diseases due to exposure to Legionella increase with age but some people are at higher risk including:
- people over 45 years of age
- smokers and heavy drinkers
- people suffering from chronic respiratory or kidney disease
- people suffering from diabetes, lung and heart disease
- anyone with an impaired immune system
Legionella control can be achieved by keeping water systems clean, preventing stagnation, and maintaining water temperatures that prevent or minimise Legionella growth.
Legionella and the Law
Legionella is classified as a Hazardous Biological Agent (HBA) in terms of the Hazardous Biological Agents Regulations (as contained it the Occupational Health and Safety Act 85 of 1993) as a Group 2 HBA, and thus demands the control of exposure of individuals to Legionella.
The starting point for any organisation is to identify the potential sources of risk of exposure to Legionella from work activities and water systems. In terms of Regulation 6, an employer must cause a risk assessment to be conducted and thereafter at intervals not exceeding two years, to determine if any person might have been exposed to the bacteria.
Duties of the Employer
If Legionella is found in the workplace, the following duties (among others) are placed on the employer:
- Ensuring that the exposure to the bacteria is monitored in accordance with a suitable procedure that is standardised, sufficiently sensitive and of proven effectiveness.
- Ensuring that all employees who are exposed undergo medical surveillance – within fourteen days of commencement of employment, and thereafter periodically.
In light of the above, the fairly recent publication of two new national standards aimed at lessening exposure to Legionella bacteria is thus of considerable importance to those working in many water-based industries and processes.
- SANS 893-1, Legionnaires’ disease Part 1: Risk management and
- SANS 893-2, Legionnaires’ disease Part 2: The control of Legionella in water systems.
The cost associated with an outbreak, in both human & financial terms, is far greater than the cost of prevention.