Legionella, the Legionnaires’ disease causing bacteria, is ubiquitous in the natural environment, especially in damp soil and water. While the organism is present more or less everywhere, water temperatures of 72–107 °F are ideal conditions for rapid growth. This explains why outbreaks of Legionnaire’s disease become more common in the summer months and have often been linked to contaminated artificial water systems – especially air conditioning units in large buildings which use water for cooling.
Studies of associations between weather variables and sporadic cases of legionnaires’ disease suggest that as temperatures rise globally so too does the prevalence of environments conducive to legionella growth. Because of this researchers at the World Health Organization (WHO) have suggested that Legionnaire’s disease should now be added to the Intergovernmental Panel on Climate Change’s list of important climate-sensitive health issues.
While warming environments are favorable for many pathogens and bacteria, the nature of how legionnaires’ disease is transmitted creates a unique risk. Researchers believe that vehicles might produce aerosols containing Legionella, as they drive on wet road surfaces in warm environments.
The risk of increased Legionnaires’ disease outbreaks is just one more reason our society must address climate change with urgency.