Cooling Towers and Preventing Legionnaire’s Disease

Ray Brennan probably looked forward to his three-day American Legion convention in Philadelphia back in the summer of ’76 – old friends, war stories, great food and maybe a little business. He probably did have a great time, which explained away the exhaustion he felt when he returned home.

But three days later, he was dead.

The convention, held at the Bellevue-Stratford Hotel in downtown Philly, kicked off July 21, 1976, according to archived coverage from the Los Angeles Times. Brennan had plenty of company there: more than 2,000 American Legion members – primarily men – converged on the hotel for three days of Legion business. Conventioneers also took in Philadelphia’s historic sights, enjoyed the cuisine all over the city and spent time with each other, shaking hands, hugging and talking.

Another three days after returning from Philadelphia, the 61-year-old Brennan, a retired U.S. Air Force captain and a bookkeeper for the Legion, died at his home – July 27, 1976. The cause of death was ruled an apparent heart attack.

Three more days passed, and suddenly, four more Legionnaires were dead, also seemingly of heart attacks. The following day, the death toll mounted to 11, with all the victims suffering the same symptoms – fatigue, chest congestion, chest pain and a fever. Older adults, smokers and people with weakened immune systems were particularly susceptible.

Three of the dead men had been patients of physician Ernest Campbell in Bloomsberg, Pennsylvania, and the doctor knew all three had attended the convention just a few days before. Recognizing the dire implications of such an epidemic, Dr. Campbell contacted the Pennsylvania Department of Health.

Meanwhile, the people at the American Legion headquarters suddenly began receiving news of members’ deaths. Within a week, two dozen were dead and more than 100 were hospitalized. In total, 221 cases were reported with 34 resulting in death.

Back in that bicentennial year, most Americans hadn’t ever heard of the U.S. Centers for Disease Control and Prevention, but it soon became a household topic. The CDC launched an exhaustive investigation that lead them to rule out external culprits – a disease carrier, or something in common ingested, for example – and began to zero in on the hotel itself.

Of course, you know the rest of the story. Months later, in January 1977, the lethal cause was identified as a bacterium the scientific community labeled Legionella. And, of course, you know where it was breeding: the cooling tower of the hotel’s air-conditioning system. From there, the bacteria then spread silently and invisibly throughout the air inside the hotel, settling in the lungs of visiting Legionnaires and blooming into a severe form of pneumonia.

“Five months after the convention, [CDC microbiologist Joseph McCade] took another look at some red sausage-shaped bacteria and concluded that they were the culprits,” Time magazine reported. “They had festered in the water of the hotel’s cooling tower and had been carried through the air as the water evaporated.”

If you’re old enough, perhaps you recall the immense relief that swept the country when the number of new cases dropped off – apparently, it wasn’t contagious. The discovery of the cause, however, spawned a whole new slate of fears because there were cooling towers in practically every building, just like the one at the Bellvue-Stratford. And it could happen again – to anyone. The fear was palpable: the public had a very loose notion of the science behind the disease and not much information on it.

Legionnaires’ disease began at least 33 years before the 1976 Philadelphia epidemic, and in the years since, it continues to claim victims.

Wikipedia offers a brief list of some of the most striking outbreaks in the past 30 years:

April 1985, England: 175 people in Stafford, England, were admitted to two local hospitals with a chest infection or pneumonia. More than two dozen did not survive. After the Legionella bacterium was found, an investigation pinpointed the source to the cooling tower on the roof of one of the hospitals.

March 1999, Holland: More than 300 people fell ill and more than 30 died of Legionnaires’ disease after attending a flower show.

July 2001, Spain: More than 800 suspected cases were recorded and six deaths reported.

September 2005, Canada: 127 nursing home residents fell ill, with 21 deaths that week. The disease was traced back to the air conditioning cooling tower.

November 2014, Portugal: More than 300 people were hospitalized and seven succumbed to the disease that festered in the cooling towers of a local fertilizer plant.

August 2015, New York City: More than 110 cases of Legionnaires’ disease and 12 related deaths were reported in the Bronx. The Department of Health determined that Legionella was found in the cooling systems of five public places, which were swiftly decontaminated.

August 2015, California: An outbreak of Legionnaires’ disease was detected at San Quentin State Prison in Northern California.

June 2015-January 2016, Michigan: Beleaguered Flint, Michigan, has suffered at least 87 cases of Legionnaires’ disease with 10 resulting in fatalities.

The original Philadelphia outbreak, of course, triggered new regulations for the climate control industry not just in this country, but across the globe. Preventing Legionnaires’ disease requires one thing: keeping Legionella from colonizing in your water system.

To understand that, let’s take a look at how a cooling tower works. It’s made to extract heat using water. Hot air intakes pass through the water, transferring heat from air to water and causing some evaporation, which rises and, when cooled, collects at the bottom of the tower and recycles for reuse, though there are restrictions for reuse in certain circumstances. Warm water is Legionella’s comfort zone, and cooling towers provide the perfect storm for this bacteria to multiply, infect silently and kill.

Proper cooling tower disinfection and maintenance practices are the key to preventing another outbreak and adding to the unfortunate death toll. Of course, a large part of that is having the proper equipment. You’ve probably got some questions and concerns about controllers and related equipment now, so give us a call at 303-232-6861 or email us at At DEWCO, we have a selection of water treatment solutions and closed systems that can help prevent this swift and silent killer from affecting your operations and taking any more victims. Give us a call today and let us help figure out the best solution for your building.