ANSI/ASHRAE Standard 188-2021 for Legionnaires’ Disease Risk Management

Green Legionella bacteria being prevented in water systems through ANSI/ASHRAE Standard 188-2021.

ANSI/ASHRAE Standard 188-2021: Legionellosis: Risk Management for Building Water Systems, an American National Standard, aims to minimize the potential for Legionnaires’ disease to spread throughout building water systems.

The bacteria Legionella was first discovered after an outbreak in 1976 among people who attended a Philadelphia convention of the American Legion (hence, Legionnaires’ disease). While it wasn’t too common for the decades that followed, Legionnaires’ disease has been on the rise since 2000, and many cases go unreported. In fact, a 2019 National Academy of Sciences, Engineering and Medicine (NASEM) report estimated that 52,000 to 70,000 Americans suffer from Legionnaires’ Disease each year, an amount substantially higher than the 10,000 reported cases in 2018.

Interestingly, prolonged quarantine measures during the COVID-19 pandemic lockdown may have expanded Legionellosis risks. Through stagnating water in devices or piping systems, harmful bacteria, including Legionella, can proliferate. A 2020 study looked at this issue in relation to the COVID-19 lockdown in Italy.

What is Legionnaires’ Disease?

Legionnaires’ disease is understood as a form of pneumonia, or lung inflammation often caused by infection, and its culprit is the Legionella bacterium, which people can be exposed to after inhaling microscopic water droplets containing the bacteria. Following exposure, Legionnaires’ disease usually develops after two to ten days, and it is marked by the initial symptoms of headache, muscle pain, chills, and a fever that can go beyond 104°F (40°C).

After a few days have passed, those inflicted with Legionnaires’ disease can experience a severe cough, shortness of breath, chest pain, gastrointestinal symptoms, and confusion or other mental changes. The disease can be fatal. The elderly, heavy smokers, people with weak immune systems, people with underlying illnesses like diabetes, and those with chronic lung disease are especially susceptible to Legionnaires’ disease. While it generally afflicts the lungs, the illness can cause infections in wounds and in other parts of the body.

Please note that the Legionella bacteria can also cause a less-severe flu-like illness known as “Pontiac fever,” as it was first identified in Pontiac, Michigan in 1968. Later on, this fever was tied to the Legionella bacteria following the burgeoning of Legionnaire’s disease. Pontiac fever usually clears up on its own.

Pontiac fever and Legionnaires’ disease are considered the two clinical forms of legionellosis.

While the Legionella bacteria enter the lungs through aspiration or by being aerosolized in water and then inhaled, Legionnaires’ disease is not contagious. In fact, there has been only one case of the bacteria transmitting from person-to-person. Legionella exist naturally in rivers, lakes, and streams, where they are relatively harmless. It is only in certain environments that the bacteria can flourish and pose a health risk.

In fact, the presence of Legionella bacteria in building water systems is not in itself sufficient to cause Legionnaires’ disease. Factors necessary for the presence of Legionnaires’ disease include building water system design and use conditions that promote the growth of Legionella, as well as a means of transmitting the bacteria to people in the building. Some outbreaks have been linked to hot tubs in cruise ships, grocery store mist machines, cooling towers in air conditioning systems, decorative fountains, swimming pools, physical therapy equipment, and water systems in hotels, hospitals, and nursing homes.

ANSI/ASHRAE Standard 188-2021

With the severity of Legionnaires’ disease and the possibility for it to emerge in connection to building water systems, there is a clear need to identify and eliminate the means by which the Legionella bacteria can multiply. ANSI/ASHRAE Standard 188-2021 is purposed with establishing minimum legionellosis risk management requirements for building water systems.

Specifically, the American National Standard provides minimum legionellosis risk management requirements for the design, operation, maintenance, repair, replacement, and expansion of new and existing buildings and their associated potable and nonpotable water systems and components. It applies to human-occupied commercial, institutional, multiunit residential, and industrial buildings, but it explicitly excludes single-family residential buildings.

ANSI/ASHRAE Standard 188-2021 outlines guidance specific to the building designer and building owner in regards to addressing building water systems. It also details provisions for a building survey, as well as general requirements necessary for any building that may need to make use of the standard’s guidance in reducing the risk of legionellosis. Furthermore, the standard touches upon subjects that may be useful for certain users of its guidelines, such as provisions for health care facilities or cooling towers.

ANSI/ASHRAE Standard 188-2021 is intended to be used by owners and managers of human-occupied buildings other than single-family residential buildings. It is also intended for those involved in the design, construction, installation, commissioning, operation, maintenance, and service of centralized building water systems and components.

ASHRAE Standing Standard Project Committee (SSPC) 188 has devoted a considerable amount of time and thought into reviewing and responding to continuous maintenance proposals and public review comments. Through these many efforts, the ANSI/ASHRAE Standard 188 is revised on a three-year basis. According to the forward of the ANSI/ASHRAE Standard 188-2021:

“The 2021 edition has benefited from the continuous maintenance proposals received and from revisions that replaced permissive language with enforceable language that will facilitate adoption of the standard for code and regulatory purposes.”

ANSI/ASHRAE Standard 188-2021: Legionellosis: Risk Management for Building Water Systems is available on the ANSI Webstore.

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