Background Legionella bacteria 4/13/2017. The Impact of The ASHRAE Standard for Legionella Control In Building Water Systems.

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1 The Impact of The ASHRAE Standard for Legionella Control In Building Water Systems Zhe Zhang, Ph.D. Background Legionnaires disease and Legionella pneumophila Legionnaire s disease: a type of pneumonia caused by Legionella pneumophila 35% of reported cases are hospital acquired High risk group: patients with compromised immune system (hospitals, nursing homes) Background Legionella bacteria Gram negative bacterium rod shaped >50 named species, over 60 serogroups L. pneumophila (sg s 1 15) accounts for approx. 90% of cases reported to the CDC L. pneumophila, serogroup 1 causes approx. 80% of cases (Most virulent 1

2 Background Legionellae bacteria : ubiquitous in natural and manmade aquatic environments Legionella proliferation: favorable water temperatures (about C), physical protection, nutrients (sediments and biofilms), and commensal microorganisms Building water systems as the source of Legionella bacteria Such as Cooling tower, decorative fountain, spa and potable water distribution system Legionnaires Disease Outbreaks CDC: Legionnaires disease cases in the United States grow nearly 4 times from 2000 to 2014, with about 5,000 people and at least 20 outbreaks a year Legionnaires Disease Outbreaks Summer 2015, New York City 138 people infected with sixteen deaths. Flint, Michigan Outbreaks From June 2014 to November 2015, at least 87 infected. 2

3 American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standard Legionellosis: Risk Management for Building Water Systems Survey You need water management plan for hot and cold water distribution system If your building meets one of following conditions: A healthcare facility treat people with chronic and acute medical problems Housing people older than 65 years Centralized hot water system More than 10 stories You also need water management plan for those water devices: Hot spa Cooling tower Decorative fountain Centrally installed mister, air washer, or humidifier Program Team.. Describe Water Systems/Flow Diagrams Analysis of Building Water Systems Control Measures Monitoring/Corrective Action Confirmation Documentation Reference: ASHRAE 188: Legionellosis: Risk Management for Building Water Systems June 26,

4 Program Team The persons responsible for the program: Build owner and manager Persons have knowledge of building water systems and water management Certified industrial hygienists Water treatment provider Microbiologist Describe Water Systems/Flow Diagrams Water receiving and distribution Location of end point uses (Cooling tower, fountain, ice machine, sinks and shower) Location of water processing ( heating, cooling, disinfection, etc.) Analysis of Building Water Systems Hazardous conditions: water temperature fluctuation, inadequate disinfectant, ph, etc. Identify the locations of hazardous conditions could occur and locations where Legionella could grow and spread Control Locations (cooling tower, hot water storage tank, water pool, spa, sink and shower etc.) 4

5 Control Measures Control Measures and Limits Water quality parameters in the distribution system Water temperature in water heater and hot water storage tank Disinfection residual and Heterotrophic Plate Count level in the cooling tower and hot tubs Monitoring/Corrective Action Physical and Chemical Parameters Corrective action are taken when systems perform outside of control limits. Confirmation Verification: establishing procedures to confirm that water management program is being implemented as designed. Validation : to confirm that water management program controls the hazardous conditions effectively Legionella testing is useful to validate the effectiveness of control measures. Both WHO and CDC acknowledge using Legionella testing as one way to verify and validate a WSP 5

6 Documentation Write it down. Impacts of ASHRAE Standard 188 US Centers for Disease Control and Prevention: Reference: ASHRAE 188: Legionellosis: Risk Management for Building Water Systems June 26, 2015 The Building Owners and Managers Association (BOMA) International is pleased to work with the U.S. Centers for Disease Control and Prevention (CDC) to help reduce the risk of Legionella in commercial properties. 6

7 USEPA referenced an ASHRAE 188 water management program as a risk management approach Impacts of ASHRAE Standard 188 Put the responsibility on all building owners and operators Litigation documentation standard or duty of care in future litigation cases. Adopted as Law Reducing cases of Legionnaires Disease Reducing healthcare costs Disinfection Methods for Legionella control in building water systems Disinfection methods Advantages Disadvantages Thermal Disinfection No special equipment needed Short-term method, time consuming, labor cost Hyperchlorination Residual protection Low efficacy corrosive Ultraviolet light No DBP, no damages to water quality No residual protection Copper-Silver ionization Chlorine dioxide Monochloamine Residual protection, Efficacy not affected by water temperature Residual protection. Effective Residual protection. Penetrate biofilm Scale Possible resistance Affected by Temperature, DBP corrosion and lead leaching, DBP, Nitrification 7

8 Question and Comments? Zhe Zhang, Ph.D. 8