Legion of Doom?

Employees returning to work after COVID 19 have another threat – Legionellosis...

Published:  05 August, 2021

For 27 years we have been practicing Health & Safety in the motor trade across the UK. In all this time we have not seen Legionellosis as being a call for concern as water systems would be in constant use. However, during these unprecedented times, many businesses in the motor industry have been forced to close for periods of time. This inactivity has given the legionella bacteria perfect breeding ground in pipe, tanks and showers.  Contrary to popular belief, Legionellosis can be fatal.
Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious Legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. The risk increases with age but some people are at higher risk. They include people over 45 years of age, smokers and heavy drinkers, people suffering from chronic respiratory or kidney disease, people suffering from diabetes, lung and heart disease, and anyone with an impaired immune system.
The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found within a company’s hot and cold water systems.

Where does it come from?
Legionella bacteria are widespread in natural water systems, e.g. rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources. Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).

How do people get it?
People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the bacteria. Certain conditions increase the risk from legionella if the water temperature in all or some parts of the system may be between 20-45°C, which is suitable for growth. It is possible for breathable water droplets to be created and dispersed e.g. aerosol-created by a cooling tower, or water outlets. There is also a risk if water is stored and/or re-circulated, and if there are deposits that can support bacterial growth providing a source of nutrients for the organism e.g. rust, sludge, scale, organic matter and biofilms.
The bacteria can multiply in water in temperatures between 20°C – 45°C. As the temperature rises above 60°C the majority of bacteria will be killed within five minutes. Maintaining water temperatures above 50°C and below 20°C is, therefore, the main method of controlling Legionella in domestic water systems as recommended by Health & Safety Authorities.

What should I do?
The incubation period is between two and 10 days so when returning back to work to a partial or unoccupied premise,  it is recommended to purge showers and water systems at the highest temperature for five minutes.

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