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  • Allison Stalker

ASHRAE Standard Issued to Prevent Legionnaires' Disease

Updated: Aug 30, 2023

In October of 2011, EES published a blog on new proposed standards created for the prevention of Legionnaires’ disease, as seen here. At the time of this post, the final standard had not been issued. Now, the standard has been published as Standard 188P, Prevention of Legionellosis Associated with Building Water System. The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., (ASHRAE), is expected to adopt this standard and some states may actually codify the standard into law.

So, why do we need this standard? First off, Legionnaires’ disease can be lethal, and at the least requires hospitalization. Death rates are between 20 and 40 percent and many of those who recover suffer permanent damage. Reported cases of the disease are on the rise with 3,522 cases reported in 2009, the most since 1976 when the Center for Disease Control (CDC) required the disease be reported. The bacteria that causes the disease has been traced to building water systems, indoor pools and spas, whirlpool spas, humidifiers, and ventilation and cooling systems. Even decorative water fountains have been identified as carrying the bacteria. The rise in frequency of this disease has produced a number of lawsuits and building closures.

Before the new standard was created, there were no clear guidelines regarded as a standard for building owners, managers, and maintenance employees to control the growth of the bacteria in building water systems. Standard 188P will be the first U.S. risk management standard that establishes clear guidelines and sets specific requirements for prevention of Legionnaires’ disease in building water systems. The standard should be used by individuals involved in the ownership, design, construction, installation, management, operation, maintenance and servicing of building water systems.

Standard 188P is based on the Hazard Analysis and Critical Control Point (HACCP) that requires maintenance protocol be written for building water systems. The following actions are required to comply with the standard:

  1. Qualitatively determine the risk characterization of the building considering various risk factors such as centralized water heaters, number of stories, if the building is an inpatient healthcare facility, the age of the occupants and the presence of whirlpools, spas, ornamental fountains, misters, air washers, or humidifiers.

    • If there are no risk factors, the only requirement is annual repetition of the survey. If there are risk factors, the standard refers to HACCP protocol listed below.

  2. Conduct a hazard analysis.

  3. Determine the critical control points (CCP).

  4. Establish critical limits for each CCP.

  5. Establish a system to monitor control of the CCP’s.

  6. Establish a corrective action to be taken when monitoring indicates that a CCP is not under control.

  7. Establish procedures for verification to confirm that the HACCP system is working effectively.

  8. Establish documentation concerning all procedures and records appropriate to these principles and their application.

If the guidelines set in Standard 188P are followed, it will allow for a much greater chance of prevention by ensuring regular water system maintenance and assessment of prevention efforts. While it will require increased effort by building owners and managers, it could prevent a Legionnaires’ outbreak and eventual legal action. To view the public review draft of the standard, click here.

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