Legionnaires’ disease is a severe form of pneumonia — lung inflammation usually caused by infection. Legionnaires’ disease is caused by a bacterium known as legionella. Legionella exist naturally in water and moist soil. They have been found in creeks and ponds, hot and cold water taps, hot water tanks, water in air conditioning cooling towers and evaporative condensers, and soil at excavation sites. You can‘t catch Legionnaires’ disease from person-to-person contact. Older adults, smokers and people with weakened immune systems are particularly susceptible to Legionnaires’ disease.
A cooling tower is a heat removal device, which extracts waste heat to the atmosphere though the cooling of a water stream to a lower temperature. Common applications for cooling towers are providing cooled water for air-conditioning, manufacturing and electric power generation. The generic term “cooling tower” is used to describe both open circuit and closed circuit heat removal equipment. The cooling tower is located on the roof of buildings and they are a part of the air – conditioning system or cooling system used for that specific building. As the system uses heat there is evaporation and it consists of water, as well as dissolved minerals and other solids in circulating water whereby some water is lost by droplets being carried out with the exhaust air (drift).
To control Legionnaires’ disease Mosman Council maintains a register of water-cooling systems in premises (including cooling towers) and warm-water systems in nursing homes and aged care facilities. Owners and occupiers who install and operate such systems must notify the Council under the Public Health Act 2010. Although building owners are responsible for cleaning and maintaining the towers, Environmental Health Officers carry out audits of the towers twice each year to ensure that they are being maintained appropriately.
The legislation control various man made environments and systems which are conducive to the growth of Legionella organisms and which are capable, under the right conditions, of transmitting Legionnaires’ disease.
These regulated systems include:
- water cooling systems
- hot water systems
- warm water systems
- air handling systems.
Council regulates water cooling systems under the Public Health Act 2010 and the Public Health (Microbial Control) Regulation 2012. These systems must also comply with AS /NZS 3666.2: 1995 and AS /NZS 3666.3: 2000. Council does not regulate air conditioners and hot water cylinders under this legislation.
Council keeps a register of the cooling towers and the owners of the premises are required to notify Council within one month of the purchase of premises which has one of these systems or within one month of the installation of one of these systems. The owner or occupier of the premises must ensure that regular maintenance is carried out and that records of such maintenance are kept on the premises. Further they are required to provide an annual certificate of Disinfection that the cooling tower complies with the requirements of the Australian standards.
Every year Council Environment Health Officers may inspect registered cooling towers to check cleanliness and the maintenance of logbooks.
Technical details about microbial control and the Code of Practice for the control of Legionnaires Disease are available at NSW Health Department – Control of Legionnaires Disease or Tel: 9477 9400.