Risks of Legionnaires' disease in reopening buildings

As businesses across Australia prepare to reopen following coronavirus (COVID-19) shutdowns, New South Wales Health (NSW Health) and industry bodies and experts are reminding building owners and occupiers of their legal obligation to ensure air-conditioning cooling towers are properly maintained, to reduce the risk of Legionnaires’ disease — caused by infection with the Legionella pneumophila bacteria.

Health guidance

“We have seen 33 cases of Legionella pneumophila in NSW between March and May this year, compared to 25 cases over the same period last year,” said Dr Richard Broome, NSW Health’s Acting Executive Director of Health Protection NSW. Public Health Units in local health districts across NSW investigate the cause of each identified case. “When a case of Legionnaires’ disease is identified, NSW Health works with the relevant local councils to ensure cooling towers in the areas visited by the case are properly maintained,” Dr Broome said.

Symptoms of the disease include: a cough, chills, fever and shortness of breath, and may lead to severe chest infections such as pneumonia. NSW Health advises that early symptoms of Legionnaires’ disease can be similar to symptoms of COVID-19, and therefore it is important to seek health advice as soon as possible. “A person’s symptoms can develop up to 10 days from the time the person is exposed to contaminated water particles in the air,” Dr Broome said. “People who develop this disease are diagnosed by chest X-ray and a urine test and usually require antibiotic treatment in hospital.”

Workplace guidance

In a workplace setting, Safe Work Australia advises that Legionella infection typically arises from exposure to a water aerosol from pooled warm water, such as occurs in association with air-conditioning cooling towers. Industry bodies and work health and safety experts across the country have warned of the potential for an outbreak of the disease as businesses reopen.

“As the COVID-19 lockdown restrictions ease, it is important that business owners ensure the safety of their building’s plumbing, air-conditioning cooling towers and water cooling systems before occupancy resumes,” said Murray Thomas, Chief Executive Officer of the Master Plumbers and Gasfitters Association of Western Australia. “Any water system that has been unused, unmanaged or unmaintained is an ideal breeding ground for Legionella bacteria.”

Thomas also advises that stagnant or low-flowing water poses additional risks, including of gastrointestinal infections and skin infections, such as those caused by fungi and Pseudomonas bacteria. “Business owners and building managers should act quickly to ensure their building’s water supply is thoroughly flushed before occupancy resumes,” Thomas said.

Risk management plan

David Hauser — Team Manager, Property Risk Audits at Greencap — recommends that affected businesses have a risk management plan in place. “One of the more significant risks associated with inadequate maintenance of a building’s heating, ventilation and air conditioning (HVAC) systems is the potential growth of Legionella and other harmful bacteria,” Hauser said. “A cooling tower risk management plan would specify procedures to enable operation on an intermittent or seasonal basis. This can be managed in one of two ways: either be drained, cleaned and kept in a dry condition, with water treatment reinstated before start-up; or be maintained in reduced operational capacity, with cooling water circulated through the entire system at least once every 48 hours.”

Like Thomas, Hauser also advises that other water-based systems within buildings should be considered: “such as decorative fountains and water features, commonly found in public spaces such as building foyers and external grounds, [which] also have the potential to generate aerosols (splashing water). Aerosols from these systems can be drawn through open windows, doors and air intakes, or onto balconies and patios increasing the risks of spread,” Hauser said. “Building owners and managers need to plan for all eventualities prior to any shutdown and should decide on controls and activities that need to be undertaken to best eliminate or mitigate risks such as Legionnaires’ disease and other bacteria build-up in their building systems.”

Image credit: ©stock.adobe.com/au/Mrsuchat