Mitigating Safety and Environmental Risks through Legionella Risk Assessment

Legionella bacteria pose a significant threat when present in a workplace or any other building where water is present. 

Conducting Legionella assessments helps organisations to ensure environmental protection, workers’ health & safety and regulatory compliance are in place and to demonstrate they follow best practices to stakeholders.

Characteristics of Legionella’s Behaviour

Legionella bacteria are common and can be found naturally in environmental water sources such as rivers, lakes and reservoirs, usually in low numbers. 

Legionella bacteria can survive under a wide variety of environmental conditions and have been found in water at temperatures between 6°C and 60°C. Water temperatures in the range from 20°C to 45°C seem to favour growth. The organisms do not appear to multiply below 20°C and will not survive above 60°C. 

They may, however, remain dormant in cool water and multiply only when water temperatures reach a suitable level. Temperatures may also influence virulence; legionella bacteria held at 37°C have greater virulence than the same legionella bacteria kept at a temperature below 25°C. 

Legionella bacteria also require a supply of nutrients to multiply. Sources can include, for example, commonly encountered organisms within the water system itself such as algae, amoebae and other bacteria. 

The presence of sediment, sludge, scale and other material within the system, together with biofilms, are also thought to play an important role in harbouring and providing favourable conditions in which the legionella bacteria may grow. 

A biofilm is a thin layer of micro-organisms which may form a slime on the surfaces in contact with water. Such biofilms, sludge and scale can protect legionella bacteria from temperatures and concentrations of biocide that would otherwise kill or inhibit these organisms if they were freely suspended in the water. 

How to mitigate Legionella risks

As legionella bacteria are commonly encountered in environmental sources, they may eventually colonize manufactured water systems and be found in cooling tower systems, hot and cold-water systems and other plant which use or store water. 

To reduce the possibility of creating conditions in which the risk from exposure to legionella bacteria is increased, it is important to control the risk by introducing measures which: 

1. Do not allow proliferation of the organisms in the water system
2. Reduce, so far as is reasonably practicable, exposure to water droplets and aerosol

Case study on legionella risk assessment for a pharmaceutical company in Pakistan

One pharmaceutical company based in Pakistan applied to SGS for a risk assessment of legionella bacterial growth and exposure potential within the water systems. 

The objective was to get recommendations for any necessary remedial and precautionary measures. 

SGS Pakistan implemented the risk assessment study based on the current versions/revisions of the HSE documents as follows:

• Approved code of practice and guidance “Legionnaires’ disease. The control of legionella bacteria in water systems. L8”
• Technical guidance “Legionnaires’ disease. HSG 274”
• Code of practice “BS 8580-1: 2019 Water quality - Risk assessments for Legionella control”
• The Health and Safety at Work etc Act 1974  
• The Control of Substances Hazardous to Health Regulations 2002

These standards have been selected as there are no local legislative guidelines in Pakistan related to Legionella control. 

The SGS risk assessors inspected the site in line with applicable site safety precautions and worked in line with SGS safety policy and procedures. 

A hazard assessment was completed prior to work commencing and some areas may not have been inspected on safety grounds.

The above-mentioned study by SGS enabled our customer to identify:

• Possible legionaries’ sources
• Potential environmental locations for growth
• Associated controls for spread or outbreak of Legionella

Conclusion

Legionella Risk Assessments play a vital role in ensuring the safety of individuals by mitigating the risks associated with Legionella bacteria. It is crucial for organizations to prioritize proper training and conduct regular water risk assessments to minimize the likelihood of a Legionnaires' disease outbreak within their premises.

Legionella is a bacteria that resides in water sources and can be transmitted through inhalation of airborne water droplets produced by hot or cold-water systems. Inhaling these contaminated droplets can lead to Legionnaires' disease, which is a severe form of pneumonia and can have fatal consequences.

By adhering to thorough legionella risk assessments and implementing appropriate control measures, organizations can significantly reduce the risks associated with Legionella bacteria. These assessments help identify potential sources of contamination, assess the level of risk, and enable the implementation of effective prevention and control measures. Regular monitoring and maintenance of water systems are crucial to ensuring the ongoing safety of individuals and preventing outbreaks of Legionnaires' disease.

Overall, a proactive approach to Legionella risk assessments is crucial in safeguarding public health and maintaining a safe environment wherever water is present.