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Recently, the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) and the National Sanitation Foundation International (NSF International) announced they are in the process of finalizing an agreement to jointly complete a building water management standard for the prevention of injury and disease associated with building water systems.
The agreement will have ASHRAE serve as the lead sponsor with the responsibility for publication and maintenance of the new standard, and NSF International will serve as a joint sponsor. The new standard will be known as ASHRAE/NSF Standard 514, Prevention of Injury and Disease Associated with Building Water Systems.
The new ASHRAE/NSF Standard 514 will take the place of the standard previously known as NSF 444, which has been in development for a couple of years but not completed. A joint committee of stakeholders, of which I was a part of, developed the existing draft of NSF 444. I, along with several other committee members, also helped develop ASHRAE Standard 188, Legionellosis: Risk Management of Building Water Systems, which was initially published in 2015.
ASHRAE Standard 188, is focused on control of Legionella bacteria in water systems, while NSF Standard 444 was intended to be a broader standard, covering prevention of injury and disease from many other waterborne pathogens.
During a conference call in January 2019 to both committees, ASHRAE and NSF staff issued this statement: “ASHRAE and NSF International agree the ASHRAE/NSF 514 standard is urgently needed to assist regulators, public health departments, building owners and health-care facilities in better managing the risk of waterborne pathogens and hazards in building water systems.” The intent is for the new ASHRAE/NSF 514 standard to reference ASHRAE 188 for control of the Legionella bacteria in building water systems while it will cover many other common water-borne pathogens.
The standard is to be developed in accordance with ANSI requirements. When it is complete, the “ANSI” designation can be added to the standard after ANSI verifies it followed the ANSI consensus development process. Then the standard can be finalized and published.
As a member of the ASHRAE committee, we have been involved with discussions for revisions to the ASHRAE 188 standard and revisions to the soon-to-be-published next edition of ASHRAE Guideline 12, which is intended to support and compliment ASHRAE 188 with supplemental information on control of Legionella bacteria in building water systems.
History of Legionnaires' Disease
Legionella was first discovered at the Bellevue Stratford Hotel in Philadelphia following a meeting of the American Legion in July 1976. More than 4,000 World War II veterans, including friends and family, were congregating Philly as part of the 58th American Legion Convention. Of those thousands of people attending the convention, around 600 of them were staying at the Bellevue Stratford Hotel.
During the second day of the convention, some of the participants began falling ill. The symptoms included fever, coughing and difficulty breathing. At the time, all the symptoms presented themselves as flu-like. Health officials initially thought a flu bug was being spread among the convention attendees. A few days later, one of the veterans from the convention died.
As the next few days passed by, more and more of the convention attendees died. By the end of the epidemic, a total of 221 people had become very sick and 34 people had died. It was not until the following year — Jan. 18, 1977 — that officials announced they had finally discovered the bacteria responsible for killing the convention attendees. However, they never determined the source of the disease as the Bellevue Stratford hotel.
Since all the people suffered respiratory symptoms, health officials surmised the illness was airborne and the bacteria entered the lungs in water vapor or aerosolized water droplets. The significant delay in the discovery and the closing of the hotel shortly after the outbreak caused the building systems to be shut down, drained, cleaned and disinfected. No water samples were collected from the plumbing systems or the cooling tower, so the actual source is not known. Testing for the source of bacteria in 1976 was not what it is now.
The term “Legionellosis” is used to describe the illness caused by any species of Legionella and includes Legionnaires’ disease and Pontiac fever. From May 1973 to October 1978, only 500 Legionellosis cases were recorded. That's not to say there were only 500 cases total. It is because most people and medical professionals were unaware of the existence of Legionella bacteria, so the majority of the cases were never tested for, reported or diagnosed correctly.
Many people during that time who died from respiratory complications such as pneumonia could have died from the bacteria but doctors must be aware of the conditions and the test for Legionella bacteria. We still have much to learn about Legionnaires' disease.
People continue to die from it and recent reports indicate a steady increase in cases each year. The media usually only reports on it when there is a death or significant outbreak of the disease. Typically, victims are patients with suppressed immune systems in health-care settings, industrial facilities or hotels.
The cause of Legionnaires' disease can be traced to a family of bacteria called Legionella, which have many known species and many known serogroups. Legionella pneumophila serogroup 1 is the specific bacterium that causes Legionnaires' disease; it has been recovered from the lung tissues of Legionnaires' disease patients. The bacteria are thought to cause another illness, called Pontiac fever, after its appearance in Pontiac, Mich., in 1968. Pontiac fever is a mild, nonpneumonic, nonfatal illness which usually lasts around three days.
Many researchers and building owners have resisted routine testing for Legionella bacteria since it is commonly found in the environment. Because of this, testing for it could raise concerns that may not be indicators of the potential for disease. However, we can control the conditions conducive for growth and reduce the chances of the bacteria growing and multiplying to a dangerous concentration.
Testing for Legionella is not mandatory and, if done, should be based on system use and environmental considerations, as well as the population living in and around the area. People with suppressed immune systems are more susceptible to become ill or die from exposure to Legionella bacteria. Hospitals, nursing homes and senior living facilities are examples of highly susceptible facilities because they have a high percentage of people with suppressed immune systems.
How Legionella Affects Humans
When Legionella bacteria enters the body, usually it is inhaled in water droplets that have been aerosolized and breathed into the lungs. The body's white blood cells begin to surround the bacteria, trying to fight it. However, the bacteria will feed on the white blood cells and use them to multiply. The body will then begin to respond by raising its temperature to fight the invader.
On average, people who acquire the Legionella infection develop a fever, causing the body temperature to rise to 104 F to 105 F. It is the optimum temperature range for the bacteria to grow and multiply. The body, with its last attempt, will try to contain the bacteria by the use of antibodies. If the body's immune system is strong enough, it will be successful at fending off the attack and thwarting the disease. The victim will likely feel sick for a few days.
The unlucky few who have weakened immune systems caused by organ transplants, smoking, chemotherapy, old age, as well as previous health conditions are more likely to be at risk for the advanced stages of the disease, where pneumonia or fluid in the lungs can be deadly.
Once a person has come in contact with the bacteria, symptoms similar to that of the common cold or flu will occur within 2 to 14 days. This is the reason the disease is so often misdiagnosed or why, in most cases, people will tend to ignore the symptoms and expect their body to get over it. By the time the symptoms have become severe, the victim is usually unable to go to the doctor without the help of someone else.
Actual testing for Legionella itself can be time-consuming. It is common for the doctor to misdiagnose the symptoms as pneumonia, prescribe the wrong medication and then allow the patient to leave. The patient will likely be back within a few days as symptoms get worse. If the bacteria concentration is high, the patient will possibly die if the diagnosis of Legionella is not caught soon enough.
Even if the doctor can diagnose the bacteria, it may already be too late. That is why it is so important to take the necessary precautions to prevent the risk of it getting up to dangerous concentrations. The actual concentration of Legionella bacteria in building water system — usually expressed in colony-forming units per milliliter of water (CFU/ml) — that is considered dangerous has no set amount.
The only way of protecting yourself is by following the guidelines of controlling Legionella bacteria growth in building water systems. This can be done by employing chemical and physical (usually temperature) methods to control bacteria growth. Having the proper plumbing piping design can be a very effective way of protecting yourself against the deadly bacteria and other organic pathogens in the water system. If you have questions about storage and delivery temperatures, contact a professional for assistance.
The effect Legionella has on the lungs is deadly. The bacteria feed and multiply exponentially, causing the lungs to fill up with fluid. The result, if not diagnosed correctly, could be a death similar to that of drowning.
Legionella is commonly found in domestic drinking water systems, cooling towers, evaporative condensers and decorative fountains. If these building water systems are not properly maintained with chemicals or physical treatment methods, the bacteria can grow to very high concentrations. Legionnaires’ disease can be transmitted if there is a source of aerosolization, such as a showerhead, a cooling tower, a decorative fountain, a hot tub or plumbing fixtures that splash; people can breathe in the aerosolized water droplets.
More than 20,000 cases of Legionnaires’ disease occur in the United States each year. In 2000, about 0.4 cases were reported per 100,000 people. In 2017, there were almost 2.4 cases per 100,000 people. It is a significant increase in the number of reported cases. This serious illness results in fatality rates ranging from 5 percent to 30 percent of those infected, according to the Centers for Disease Control and Prevention (CDC). Individuals with weak immune systems are the most susceptible.
The organism is commonly found in water-cooled, heat transfer systems such as cooling towers, hot tubs and domestic hot water systems, but it is generally only transmitted to humans through airborne particles. Dispersal of Legionella through aerosol or misting of contaminated water leads to individual and sometimes widespread illness.
Sources of aerosol dispersal include showers, produce misters, hot tubs, decorative fountains or water features and cooling towers. While cooling towers are considered the prime source of Legionella bacteria growth and dispersal, ongoing research finds that domestic hot water systems are a very common source of Legionella colonization.
The growth of Legionella bacterial colonies is often supported by “dead legs” in plumbing systems; they allow scale and biofilms to grow in ideal temperature conditions. Dead legs are generally pipe sections with no flow and are more than five pipe diameters. Dead legs should be flushed on a regular basis depending on the water conditions at a facility.
Water temperatures also play a role with bacteria growth; systems that mix hot and cold water should be maintained above 124 F throughout the entire distribution and return piping system. Temperature-limiting devices should be used at showers, bathtubs and sinks to prevent scalding. There are several common techniques to disinfect water systems for Legionella organism control but proven effectiveness varies.
Building water systems should undergo a complete evaluation and a system flow diagram should be developed identifying all pipe, valves, temperature control, temperature measuring and sampling points. It should include a risk assessment narrative and suggestions for control limits for the building water systems.
Following are a few examples of things you should consider when developing a water management and risk analysis plan to minimize the risk of Legionella bacteria growth in a building water system.
Piping system design to minimize bacteria growth; Extend recirculation lines to the point farthest from the supply and maintain temperatures above 124 F at the point where the hot water return gets back to the water heater; Run all lines at a slight fall to drains at low points to make draining the system easier and make piping take-offs and connections to reduce airlocks and trapped sections of piping; Run hot piping above cold piping to prevent warming of cold water; Run hot piping as far away from cold water piping as possible to minimize heat transfer to cold water piping; and Ream all pipe ends to remove burrs. Burrs can trap sediments and allow a food source for Legionella. Burrs also can create local turbulence, which can cause erosion.
In addition: Minimize cool zones in hot water storage tanks by recirculating the hot water system and storing hot water at or above 140 F; A good system design would maintain a temperature above about 124 F at all parts of the system; Install thermometers: at the inlet and outlet of all water heaters; in the hot water return piping just ahead of the hot water return circulating pump, which should be located near the water heater; and at the inlets and outlet of all mixing valves; and Digital temperature actuated mixing valves should be used to control the entire hot water supply and return distribution loop or major sections of the circulated distribution system. Balancing valves should be used for branches. This allows temperatures to be high enough in the water heater to pasteurize the water and prevent Legionella bacteria from growing in the hot water tank. Point-of-use mixing valves or temperature-limiting devices should be used to limit the water temperatures at fixtures and prevent scalding.
2019 ASHRAE Winter Conference, AHR Expo
I attended the 2019 Winter Conference and AHR Expo in Atlanta, Jan. 12-16. The headquarters hotel was the Omni Hotel Atlanta at CNN Center and the expo was held at the Georgia World Congress Center, which was the same location as the ASPE convention and expo in fall 2018. I experienced a lot of dèjá vu moments as the meetings and trade show were in the same spaces.
The AHR Expo attracted HVACR professionals from around the globe and provided a forum for manufacturers to showcase the latest products and services. It drew more than 65,000 attendees and had 1,809 total exhibitors; 496 international exhibitors came from 35 countries. There were 107 first-time exhibitors.
The Winter Conference technical program featured more than 300 presentations, with interest surrounding this year’s new track, Renewable and Natural Systems. Session topics included exploring energy technologies, renewable energy sources and the future of the smart grid.
2018-2019 ASHRAE President Sheila J. Hayter, P.E., says ASHRAE looks to explore ways to incorporate renewable energy technologies into integrated building concepts and the organization will take an even greater leadership role in defining the relationship between buildings and the power sector.
The ASHRAE Learning Institute (ALI) was held during the conference and offered five full-day seminars and 15 half-day courses.
ASHRAE recognized outstanding achievements and contributions of dedicated members to the HVACR industry during its honors and awards program. A special presentation was made to H.E. (Barney) Burroughs, presidential Fellow Life Member ASHRAE, for his 100th ASHRAE conference. (The group has a winter and summer conference each year.)
The slate of nominees for 2019-2020 board officers and directors were announced: President-Elect: Chuck Gulledge; Treasurer: Mick Schwedler; Vice Presidents: Bill McQuade, Bill Dean, Dennis Knight and Farooq Mehboob; Director and regional chairs: Steve Marek (Region IV), Douglas Zentz (Region V), Richard Hermans (Region VI), Robin Bryant (Region XII) and Apichit Lumlertpongpana (Region XIII); Directors-at-large: Kelley Cramm, Jaap Hogeling and Ashish Rakheja; Alternate director-at-large: Kishor Khankari. Elections will be held in May.
The 2019 ASHRAE Annual Conference will take place June 22-26 in Kansas City, with the 2020 Winter Conference Feb. 1-5, 2020, and the AHR Expo, Feb. 3-5, in Orlando, Fla.