April 7, 2017

What is Legionella?

Legionnaires’ disease is a very serious type of pneumonia caused by breathing in small droplets of water that contain bacteria called Legionella. Signs and symptoms of Legionnaires’ disease can include cough, muscle aches, fever, shortness of breath and headache. This disease is treated with antibiotics and most people who get sick need care in a hospital, but make a full recovery, however, according to the U.S. Department of Health and Human Services, about 1 out of 10 people who get Legionnaires’ disease will die from the infection.

The Legionella bacteria is found naturally in moist environments, such as lakes, rivers, creeks and other water sources at temperatures ranging from 5°C to 55°C. There have been no recorded cases of Legionnaires’ disease caused by Legionella in the natural environment, but water containing the bacteria does present a risk when it is dispersed into the air as an aerosol.

How is Legionella bacteria transmitted?

Epidemiological evidence indicates that all patients acquire the disease from environmental water or moisture habitats, particularly amplifiers of Legionella growth, such as cooling towers, warm water systems and garden potting mix. The route of infection is largely, if not exclusively, through inhalation of contaminated aerosols or very fine dust particles, as in the case of garden potting mix. The aerosols must be large enough to hold the bacteria, between one and five microns in size. To contract Legionnaires’ disease, a person has to inhale the contaminated particles deeply into the lungs and they must be susceptible to it.

Can evaporative coolers transmit the disease?

Properly maintained evaporative coolers will not transmit the disease because they produce no aerosols. Evaporative air coolers should not be confused with cooling towers or evaporative condensers, which involve different technology.

Evaporative coolers cool air close to its wet bulb temperature: in order to cool, the water temperature has to be below the air temperature, and so water very rarely rises above 20°C, outside the Legionella risk range.

Secondly, in good evaporative coolers, water is drained from the unit when it is not required, so there is no standing water to rise to ambient temperature.

But above all, as we have said, a well designed evaporative cooler such as Breezair do not produce any aerosol, meaning that even if bacteria were present in the cooler, there is still no mechanism there to transfer them to humans.

Moreover, there are no recorded cases of evaporative coolers causing Legionnaires’ disease and research indicates transmission of the bacteria is not possible by the evaporative method.

Legionnaires’ Disease – why evaporative coolers pose no risk to your health