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Legionella concern as office buildings reopen

By Stacy Gittleman



Across the nation, schools, businesses, and office spaces are embroiled in what is known as “hygiene theater” to assure the public that indoor spaces are safe to return to work, learn, shop, exercise and dine in once the pandemic ebbs. Back at the office, workspace experts are trying their best to implement guidelines from the United States Centers for Disease Control and Prevention (CDC), repartitioning and reconfiguring layouts to maximize physical distancing of desks, installing plexiglass barriers and posting one-way foot traffic signs around workstations. Some schools and businesses have deployed high-tech devices for temperature checks as the world figures out how to get back to a new, post-pandemic normal.


But prolonged inactivity in all the buildings we normally occupy in day-to-day life has heightened the presence of another underlying hazard lurking in our man-made water systems that not even the CDC’s offices in Atlanta could evade: the presence of Legionella.


In August 2020, the CDC itself shuttered some of its office space because Legionella, a pathogen that exists naturally in surface waters but causes a deadly strain of pneumonia and other flu-like illnesses once it is allowed to grow in indoor water systems, was discovered due to a prolonged pandemic shutdown.


It is a warning to any building or facility manager that buildings were built to be used and run continually. Months of inactivity in office buildings have created an ideal environment for the growth of Legionella, which spreads in airborne water droplets that come from drinking fountains, hot tubs, sinks, toilets, sprinklers, showers, and air-conditioning systems.


Although there are plenty of guidelines on how to assess and manage the risk of Legionella in a building’s water system from professional standards associations and state and federal government agencies, they offer inconsistent advice. What's more, there are no government regulations mandating inspections to make sure building managers are properly putting these guidelines into action. Only New York has Legionella legislation that mandates regulations for healthcare buildings in their state.


Public health officials from the federal to the local level insist that practicing risk management to prevent Legionella is essentially a voluntary exercise for school districts, office buildings, gyms and the hospitality industry.


“Research shows that most office building owners do not test for Legionella, and the older the building, the likelier the bacteria is to show up, especially if buildings have been closed since the pandemic started,” said Jasen Kunz, commander of environmental health officer for the Water, Food, and Environmental Health Services Branch at CDC’s National Center for Environmental Health. “The temporary shutdown or reduced operation of schools and buildings, along with reductions in normal water use, can create hazards for returning students and staff.”


Kunz said that unless a cluster of cases arise, there is usually little to no testing in building settings for the pathogen. Sources from epidemiologists to environmental engineers agree that Legionella outbreaks and their numbers are even more challenging to pin down because Legionella is a form of pneumonia.


The name Legionnaire’s Disease (LD) was coined in 1976 when guests of the Philadelphia Stratford Hotel attending an American Legion conference contracted an unusual strain of pneumonia after being exposed to the Legionella bacteria, resulting in 34 deaths and 221 additional cases of the disease.


Pontiac fever, a non-fatal form of legionellosis, was discovered in 1968 in Pontiac, Michigan, when several Oakland Country health department workers were struck with a flu-like illness traced back to the pathogen.


According to the CDC, people older than 50 and those with underlying comorbidities, are most susceptible to infection, including current and former smokers, heavy drinkers, those with compromised immune systems, or with chronic lung disease. Most healthy people do not – or will not – get sick after being exposed to the pathogen.


The CDC estimates annual cases of the disease tally at 25,000, but only 5,000 cases are reported, because of its nonspecific signs and symptoms. Ten percent of those who become infected with Legionnaire's Disease will die from the infection. Legionnaire's Disease in children is not common and the disease is not transmitted from human to human. Domestic cases have grown ninefold since 2000, though the CDC states it is unclear if this growth is due to an aging, more susceptible population or other factors. To complicate matters, Legionnaire's Disease’s symptoms – cough, shortness of breath, fever, and chills – present the same way as COVID-19 and have a similar incubation period. While COVID-19 testing is determined with a nasal swab, Legionnaire's Disease is diagnosed through urinalysis.


At the state level, Michigan Department of Health and Human Services (MDHHS) Public Information Officer Lynn Sutfin said Legionnaire's Disease cases have been on a downward trend since the start of the pandemic. Before the 2020 shutdown, the state reported 52 cases as of March 31, 2020. The latest statistics show that as of March 2021, there have been 34 reported cases. In 2019, there were between 479 and 554 cases in the state, with 77 of those cases concentrated in Macomb County.


To understand the tricky nature of Legionella and why it is so difficult to remediate once it colonizes in a plumbing system, University of Michigan Microbiology and Immunology Professor Michele Swanson said the issue needs to be looked at from the molecular level.


Legionella exists in the natural world in bodies of water. Once it gets into manmade water systems like the plumbing of a large building, it favors stagnant water at tepid to lukewarm temperatures. Eventually, microbial colonies of Legionella adhere to another form of bacteria known as a biofilm, which forms a sticky mat that nestles inside pipes, especially ones that are corroding and leaching lead, copper, or iron.


Swanson said flushing a water system with biocides or extra chlorine may kill the Legionella floating in a water stream, but it is harder to rid pipes of Legionella clinging to the sticky biofilm, especially if it is in the pipes of a remote section of a complex, multistoried building. Water pumped at the necessary high temperatures (between 120-140 degrees F) may remediate the problem, but that may also be damaging to a building's plumbing and water heater. Also, pumping a water system with high levels of chlorine or other disinfectants cannot be done safely when the public is in a building.


Swanson said within a school setting, it is not young children who are vulnerable but any staff member who may have a compromised immune system. Though Legionella has an airborne nature, she said it does not grow in heating or air conditioning vents and is strictly found in waterworks.


In 2018, Swanson and eight mostly Michigan-based researchers authored a National Academy of Sciences (NAS) paper, Assessment of the Legionnaires’ Disease outbreak in Flint, Michigan (2018). The work chronicled an 18-month study that determined that the city drastically worsened its water quality and risk for Legionella.


Between 2014 and 2015, public health officials reported 90 Legionnaires' cases in Flint and at least a dozen people died of the illness. The bulk of the cases stemmed from McLaren Flint Hospital, which had been a hotbed of the disease for nearly a decade.


The NAS paper concluded that the risk of Legionella exposure in Flint jumped as much as 80 percent in some neighborhoods when water sourcing was switched from the Detroit system to the Flint River with reduced chlorine levels as a decontaminant in its water infrastructure.


Swanson also pointed to other examples of deadly Legionnaire's Disease outbreaks at the Quincy Veteran’s Center in Illinois between 2015-2018, as a reason why there should be more conversation, and then legislation, to regulate Legionella risk management practices.


“There are many guidelines from different levels of government but putting the practices into place the right way to prevent Legionella outbreaks is voluntary in all states,” said Swanson. “Only New York State has some limited regulations in place involving prevention of Legionella (in water cooling towers). One of the lessons we can learn from Flint is that we need to have more conversations about this in Congress. “


Shawn McElmurry, an associate professor of environmental engineering at Wayne State University, who also authored the NAS paper, said that Flint’s long-lasting water crisis is an example of the importance of understanding the intersection of water supply and public health and the need for transparency and reporting Legionella detection once it is found in a water system.


“The more that drinking health systems seamlessly interact with public health systems and infrastructure, the more resilient both can be in keeping the general public healthy,” said McElmurry.


McElmurry said he and other public health experts in academia viewed the stay-at-home orders of the pandemic as a major challenge to facility management. Buildings that ordinarily get a great deal of usage during the work and school week have their water systems flushed and moving with hot and cold water and disinfectants and anti-corrosive chemicals that keep both people and pipes healthy with daily use. When the flow came to a halt at the onset of the pandemic, McElmurry said building and facility managers should have been more proactive in establishing flushing routines and water maintenance plans as recommended by OSHA, the CDC, the EPA, and waterworks associations such as the American Water Works Association.


Wayne State University is no stranger to Legionella woes. In 2018, during a routine inspection, the microbe was detected in three water cooling towers and in three bathrooms at the WSU campus, and one employee was diagnosed with Legionnaire's Disease. In all, testing at WSU in 2018-2019 revealed significant Legionella blooms in the water systems of 25 buildings across campus, all of which were treated.


As a result, McElmurry said WSU took a “very aggressive” stance in Legionella monitoring and established its water safety program. Each week, campus building managers inspect, test, sample, and monitor the campus water system to ensure it is acting within federal, state, and local guidelines. The team works to monitor water quality and implement measures to ensure the safety of the Wayne State community. 


Soon after classes at WSU went online during COVID, McElmurry said the university’s water safety committee “stepped up its water flushing routine.” Building management staff went floor to floor flushing sinks and faucets in buildings and reminded students to do the same in dorm bathrooms.


“I cannot stress enough the importance of initiating a flushing routine as a preventative measure and this should have been happening before students, staff, and workers return to buildings,” said McElmurry. “There needs to be assessments of water systems before people return to in-person work and school. It is much more difficult to rid a system of Legionella and the whole point of having a water management plan with routine and regular flushing is to prevent it from happening in the first place.”


Most sources interviewed in this article pointed to standards written by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) as the authority on Legionella risk management. ASHRAE standards document detailed prevention, testing, flushing requirements for building water systems and in detail describe environmental conditions that promote the growth of Legionella. Available for free online and specifically written to tackle COVID-19 questions, ASHRAE Standard 188 developed guidance for precautions building owners and operators should take before reopening buildings. Many of these precautions are specifically addressed toward the prevention of Legionella exposures.


In addition to establishing a flushing regimen that is customized to a building's specifications, ASHRAE advises that a building's water supply must be kept at an optimal temperature. Legionella favors tepid water (70-110 degrees), so the CDC and OSHA recommend buildings keep hot water tanks set at 140 degrees so hot water at this temperature can consistently reach all water fixtures. Any water in a looped water system must be kept at 120 degrees.


Among the associations providing detailed recommendations to its water authority clients, including the Oakland County Water Resources Commission and the Great Lakes Water Authority, is the American Water Works Association (AWWA).


Noting that it takes time, institutional support, funding, and personnel – things that may all be in short supply during a pandemic – to develop a water management plan – the AWWA for its members authored in October 2020, Responding to Water Stagnation in Buildings with Reduced or No Water Use. The free, 30-page paper is authored by national experts on waterborne illnesses and gives detailed instructions based on how buildings of different sizes and functions should properly maintain building water systems and respond to any detection of legionella – important advice for large and small commercial buildings where employees have been working virtually for over a year.


“Water is oftentimes the last thing people think about when returning to an office or school building,” said Bonnifer Ballard, head of the AWWA Michigan Section. “The AWWA provides guidance and resources to our members, many of them who are water authorities, but even individuals who own second or summer homes, if they have not been in those homes for a while, really need to be vigilant and flush their water lines thoroughly if they have not been used in a while.”


Ballard said when it comes to water management in interior environments, it is incumbent that commercial building managers have a direct partnership with health departments at all governmental levels, and hopes in the future that the Michigan state legislature will pay better attention to this issue by calling for requirements to test for the microbe.


Philadelphia-based Tim Keane is an environmental engineer and consul