Legionella is a common bacterium in nature. One can contract the Legionella bacterium via the respiratory tract, but not everyone who is exposed becomes ill. The health effects caused by the Legionella bacterium range from flu-like symptoms to pneumonia. Most of those infected by the bacterium will never notice they were infected.
Legionella has been found in about half of the forest industry wastewater treatment plants that have been investigated. The water purification process in biological wastewater treatment plants is based on microbes feeding off impurities in wastewater. This is why the legionella bacterium also thrives in wastewater treatment plants.
Legionella has entered wastewater treatment plants from nature. Conditions in natural waterways are not as favourable to the reproduction of legionella as they are in warm process water.
Forest industry occupational health experts have instructed employees at wastewater treatment plants to use breathing masks.
The Finnish forest industry, the National Institute for Health and Welfare, and the Finnish Institute of Occupational Health have studied the incidence of legionella at production facilities. Legionella has also been discussed with other authorities. Its incidence and prevention methods have been continuously monitored and investigated. Plants have adopted risk management procedures.