You Might Like
On FacilitiesNet

Building Operating Management

ASHRAE Legionella Standard: Monitoring, Disinfection, Legal Considerations

Monitoring for Legionella is the key to prevention. Testing your water system is the only way to confirm the presence of Legionella. Studies show there are no substitutes for testing — including the temperature, chlorine, and disinfectant residual — that can predict the presence or absence of Legionella. For example, total bacterial counts (HPC) aren't predictive of the presence or absence of Legionella. Simply put, if you don't test, you don't know. Leading experts in the detection and remediation of Legionella have recommended culturing water to assess risk and to verify the efficacy of disinfection.


If a Legionnaires' disease or Pontiac fever outbreak is suspected to have originated from your water system, ASHRAE 188 requires disinfection. Chemical and thermal systems or a combination are recommended. Selecting a disinfection method that works best requires analysis based on efficacy, cost, installation and maintenance. No disinfection technique can be successful without a conscientious monitoring program and a committed staff. If a disinfection system is installed, Legionella site positivity and disinfectant concentrations need to be routinely monitored — often for the life of the system.

Legionella Expertise Recommended

While the standard goes a long way in providing guidance to control Legionella, it is by no means an exhaustive guide for effective prevention and disinfection. Indeed, according to some industry experts, some of the methods of disinfection mentioned in the standard are of questionable effectiveness in controlling Legionella. Given that Standard 188 requires that the risk assessment team include persons knowledgeable in Legionella and HACCP, this may require seeking outside consultation with professionals. In addition, we recommend reviewing other guidance documents and current publications on the prevention and control of Legionnaires' disease (see www.legionella.org).

Impact of Standard 188 on Legal Liability

Where ASHRAE Standard 188 is adopted in building codes, it will have the force of law. Even where not formally made part of a code, standards such as this are often argued to establish best practices for the industry. Compliance with a standard can assist in establishing compliance with the industry standard of care. Conversely, if compliance is not attempted or achieved, you can expect that a plaintiff will argue that the defendant(s) could have acted to prevent the injury but chose not to do so.

While the increased accountability contained in Standard 188 will call for increased risk management, compliance with these measures should translate into greater protection from accusations of negligence in those instances where illness or death is alleged to have occurred.

Facility managers following guidelines issued by organizations other than ASHRAE may want to do more research or seek assistance on how to develop, implement, and maintain your plan to comport with ASHRAE Standard 188. In addition, using both an accredited and CDC-ELITE (Environmental Legionella Isolation Techniques Evaluation) certified lab for Legionella testing can give you the confidence your treatment methods are capably performed and save you time and money. Overall, the new ASHRAE standard gives facility managers the basic steps they need to implement a plan to control Legionella while saving lives and avoiding the time and expense of contentious claims and litigation.

Janet E. Stout, Ph.D., is director, Special Pathogens Laboratory in Pittsburgh, Penn. A microbiologist, she is an internationally recognized expert on Legionnaires' disease, and is on the ASHRAE committee responsible for the proposed ASHRAE standard. She can be reached at jstout@specialpathogenslab.com.

Garry R. Boehlert, Esq., is a partner in the Washington, D.C., office of Saul Ewing, LLP. He is experienced in Legionellosis litigation. He can be reached at gboehlert@saul.com.

Contact FacilitiesNet Editorial Staff »

  posted on 2/3/2012   Article Use Policy

Related Topics: