Legionella in Your Air

Many types of bacteria exist which can impact our indoor air quality. Legionella is one such bacterium which could result in serious health issues to exposed individuals.

Legionellosis, or Legionnaire’s Disease, is caused by the waterborne Legionella bacterium that grows best in slow moving or still, warm water. The primary route of exposure to building occupants is through an aerosol effect, most commonly from evaporative cooling towers or showerheads.

The term Legionnaires’ Disease first gained attention after a number of American Legionnaires, who were in Philadelphia and attending an American Legion convention, started to fall ill by an unknown illness.  Upon returning home from the convention, a mysterios respiratory epidemin, with fatal consequences, befell many of the convention atendees.  Investigations into the source of the outbreake concluded that the illnesses were developed as a result of exposure to a bacterium, Legionella Pheumophilia, which had been spread by the hotel’s air conditioning system via aerosols and inhailed by those attending the convention.

A common source of Legionella in commercial buildings is from poorly placed or maintained evaporative cooling towers which often release water in an aerosol which may enter nearby ventilation intakes. Outdoor fountains near buildings or outdoor attractions have also been known to carry the Legionella bacteria.  Jacuzzi tubs or spas are also a typical legionella breeding ground as well as showers, CPAP machines and body misters.

High rick groups who are more susceptible to developing illness after being exposed to the legionella bacteria include the elderly, those with pre-existing illness, respiratory conditions, heart conditions, the very young, and those with an immuno-supression.

Ideal conditions where the legionella bacteria can thrive are in waters with a ph level between 5-8.5, higher temperature waters between 20-50 degrees celcius with the most optimal growth conditions occuring in temperatures between 35 and 46 degrees celcius.

A proactive approach to legionella testing, combined with a thorough legionella management plan is the best approach to prevention.