Standard 188: A Good Start to Preventing Legionnaires' Disease
While ANSI/ASHRAE Standard 188-2015 is a good start to preventing Legionnaires’ disease associated with building water systems, it provides only the basic requirements to manage the risk of Legionella in building water systems. What’s more, the standard outlines what owners should do, but not how to do it. This creates gaps when it comes to Legionella control--gaps that could open building owners to liability claims. These gaps include:
1. The “Water Management Program Team" convened must have "knowledge of the building water system design and water management as it relates to Legionellosis." What isn't said is that knowledge of Legionella will typically need to come from outside the organization for effective management.
2. ASHRAE 188 does not require Legionella testing to validate if your risk management program is working. But the only reliable way to validate efficacy of your program and disinfectant (if you are using one) and the threat from Legionella is to test for Legionella. The International Organization for Standardization has a method that is accepted internationally as best practice for Legionella culture. It is spelled out in ISO 11731 -1998, “Water Quality - Detection and Enumeration of Legionella.” Variations of this method are reliably used by the Centers for Disease Control and Prevention and other laboratories proficient in Legionella testing.
3. ASHRAE 188 requires hazardous conditions be redressed to “acceptable” levels without providing a definition of “acceptable.” That’s left up to you.
4. Compliance is based on going through the steps indicated in the standard not whether your plan is effective.
Some of these "gaps" may be addressed in future iterations of the standard because ASHRAE has placed the standard on "continuous maintenance” thereby providing a mechanism for changes to be made through this process.
Standard 188 also states that, “Water Management Program Team shall have knowledge of the building water system design and water management as it relates to Legionellosis.” However, most building owners don’t possess the necessary specialized knowledge of Legionella in the built environment, and many will need to consult specialists outside their organization. For example, the presence of Legionella can be impacted by:
— How water systems are operated and maintained affects water quality, including:
— The types of fixtures
— Flow patterns/restrictions
— Materials of construction
— Type of municipal water treatment
— Where and what types of Legionella are present? Are they disease-causing strains?
The above factors contribute to whether the building is at sufficient risk to warrant consideration of secondary disinfection. This means that, for the first time, many building owners could be confronted with deciding whether or not to install a disinfection system. This can be challenging because there is no “one size fits all” technology and choosing a technology requires knowledge of Legionella and engineering, as well as water treatment expertise.
WATERSHED EVENTS: ASHRAE 188 and NEW YORK REGULATION
ASHRAE 188 was passed just a few weeks before the largest recorded outbreak in New York City history (130 cases and 12 deaths). However, unlike cities and states that have faced outbreaks of Legionnaires’ disease in the past, New York City and New York State took an unprecedented approach by enacting emergency regulation under then New York State health law for Legionella control in cooling towers — which are believed to be the source of the outbreak—both city- and statewide.
This regulation could be a game changer for Legionnaires’ disease prevention by "requiring all owners of cooling towers to ensure proper maintenance of cooling towers to protect the public and address this public health threat." Elements from the new ASHRAE standard are included in the regulation and require a water management plan, disinfection and registration of cooling towers.
Adopting the brand new — yet untested — ASHRAE standard into a regulation was a bold move but bolder still was the inclusion of a cooling tower control strategy. Unlike ASHARE 188, the cooling tower control strategy gives actionable information for interpretation of Legionella test results. When Legionella reaches a specific level of colony forming units (CFU), incremental changes in water treatment are recommended. The strategy is based on the Australian / New Zealand guideline, and is one Special Pathogens Laboratory has recommended and have referenced for years.
Additionally, while the ASHRAE standard doesn’t require Legionella testing, the New York regulation has filled that gap. The regulation requires scheduled testing of cooling towers and testing of potable water in hospitals and health care facilities including residential healthcare (i.e., nursing homes). For example, Section 4.6 requires that the long-term plan includes testing for Legionella.
Studies show that Legionella bacteria can be present in approximately 50 percent of buildings and in at least in 30 percent of cooling towers. The only way to confirm that Legionella is under control is to culture water for Legionella — a step that Standard 188 leaves to the discretion of the building water management team. Other international guidelines and standards recommend proactive testing for Legionella, especially in hospitals and nursing homes where building occupants are at the greatest risk of contracting the disease.
This aggressive move in New York on the heels of Standard 188 could accelerate its adoption into other state and local codes. Where that happens, ASHRAE 188 will have the force of law.