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In July of 1976, 221 American Legionnaires were stricken by a mysterious lung ailment in a Philadelphia hotel. Within days, 34 of the members died. After months of investigation, the cause, later named the Legionella bacteria, was isolated in the cooling tower of the hotel’s air conditioning system. The bacteria had spread throughout the hotel, propelled by the cooled air of the HVAC system.

Now commonly referred to as Legionnaires’ Disease, Legionellosis is the respiratory disease caused by the Legionella bacteria. Legionnaires’ Disease is the most severe form of Legionellosis, a dangerous form of pneumonia and lung infection.

A less severe response to Legionella is Pontiac Fever, less dangerous but exhibiting many of the same symptoms.

According to the Center for Disease Control (CDC), some individuals are more at risk than others when they inhale the fine airborne water droplets that contain the bacteria. The most susceptible people over 55 years of age, smokers, and people with chronic lung problems or weakened immune systems.

The Role of HVAC in Spreading Legionella

Since that original outbreak, several more cases have been discovered and traced to HVAC systems. In fact, the two most common sources of the bacteria have been cooling towers and large central air conditioning systems. The bacteria most often thrives in warm, stagnant water present in cooling towers. Other sources are shower heads, hot tubs, and indoor fountains..

CDC estimates that at least 18,000 people per year are hospitalized by the effects of the Legionella bacteria. While Legionellosis is treatable if administered in a reasonable time, proactive maintenance activity must take place to prevent the problem.

ASHRAE Protocol for HAACP

The American Society of Heating, Refrigerating, and Air Conditioning (ASHRAE) has recognized the potential severity of the spread of Legionellosis through HVAC and water systems. In 2011, the group presented Standard 188, a protocol outlining inspection, detection, and the establishment of pertinent HAACP programs to identify threats,

HVAC Design Considerations

When designing an HVAC system, the following guidelines will reduce the potential for LBD and other bacteria transmissions:

  • Minimize the use of reservoirs and water pans.
  • Install drain water sump pumps to evacuate water when not in use.
  • Bleed water sumps te eliminate the development of solids.
  • Slope or tilt collection pans and sumps to drain water.
  • Ensure that air intakes situated are away from steam sources, humidifiers or other moisture-producing elements such as cooling towers.

The Importance of Industrial & Commercial HVAC Maintenance

To protect inhabitants of public buildings and workplaces, OSHA (Occupational Safety and Health Administration) has very specific guidelines to maintain a safe environment.

Recognizing that the Legionnaires Disease Bacteria (LBD) cannot exist without the presence of water, HVAC systems for public places must be properly maintained. Keeping LBD-contaminated water from entering the system is essential. The key mandate is to install and operate the equipment exactly as designed. Likewise, maintaining and regularly testing the system is necessary.

Regular Professional Inspection & Maintenance

The potential presence of LBD is a severe threat to any building’s HVAC system. The best defense is regular inspection and preventative maintenance. Understanding what and where to look for is necessary. Trained and licensed professionals are capable of identifying problem conditions and correct them before trouble arises.

When you need mechanical services in Chicago, Illinois, our certified technicians are here to provide you with the most economical solutions. Contact us to schedule an appointment.