ENVIRONMENT and ENERGY
37 identification and characterisation. Other methods, such as molecular( PCR), serological or rapid analysis tests, are not evaluated under this programme, and neither are sampling methods.
• Lucas et al.( 2011) reported on the results of a pilot study for the ELITE Programme, which was conducted from September 2008 to March 2009. One of the issues reported with routine sampling is the variability in recovery of legionellae from repeated sampling of sites, as documented by several researchers. In one study of variability, Flanders et al.( 2014) evaluated the effects of sample holding and shipping times on legionella test results while taking into account measurement errors. Based on 159 original samples and 2 544 split samples, the authors determined that holding time increased the root mean squared error by 3 – 8 %.
• There is a lack of standardised protocols for the selection of sampling sites and the frequency of sampling( Lucas et al., 2011; WHO, 2007).
Guidelines on routine environmental testing for legionella vary among different agencies, including the CDC, WHO, AIHA and ASHRAE.
• AIHA( 2015) recommended using validated laboratory methods to measure viable legionella bacteria rather than surrogate indicators( for example chlorine residual) as part of routine assessments on a semiannual frequency. AIHA also suggests that legionella testing should be conducted for validation of the plan( that is, confirming that the plan is effective at controlling the identified hazards), and as part of the outbreak investigation to determine the environmental source of the disease( AIHA, 2015).
• ASHRAE( 2015) suggested that the team responsible for developing and implementing the building’ s risk management plan for legionella control decide whether legionella testing should be conducted. Criteria that can support such a decision include prior history of legionellosis, buildings that serve at-risk or immunocompromised populations, and the incorporation of control limits( that is, defined values for chemical or physical parameters) into the risk management programme( ASHRAE, 2015; HSE, 2014).
• HSE( 2014) suggests that monthly legionella testing be conducted in premise plumbing systems that provide treatment with biocides and where water is stored or distribution temperatures are reduced. Monitoring is expected to continue until treatment effectiveness and control can be confirmed. HSE provides additional guidance on sampling locations in hot and cold water systems.
• VHA( 2014) recommends routine environmental testing for legionella in VHA facilities as a way to validate the effectiveness of measures for legionella control.
• The Maryland Department of Health and Mental Hygiene( 2000) recommends that water distribution systems within acute care hospitals be routinely cultured for legionella at a facility-specific schedule determined by risk assessment.
Despite the limitations of environmental monitoring, both WHO and CDC acknowledge using legionella testing as one way to verify and validate a WSP( Garrison et al., 2015; WHO, 2007).
If a decision is made to conduct routine environmental testing for legionella as part of a risk management approach, studies recommend that a building-specific sampling plan be developed that specifies the location of sampling sites, the type of samples, the frequency of sampling, the sample collection method and the sample analysis method( AIHA, 2015; Krageschmidt et al., 2014). Ditommaso et al.( 2010) concluded that hospitals could adopt a simple and efficient environmental sampling strategy for legionella testing in hot water systems by conducting water sampling, including water from the recirculation loop and excluding biofilm sampling. However, there is no consensus on how many and which types of samples to take( for example, bulk water or biofilm), nor how often to perform the sampling to accurately assess the risk from legionella.
Keywords for identifying the areas of responsibility of the designer and the installer
Complex plumbing systems Dead-end Design phase Distribution piping design systems Greater energy use Greater than 60 ° C Hot and cold temperatures Hot water distribution system Ideally grow Increase scalding risks
Multi-storey building Outlets reaching 55 ° C Plumbing systems Proper maintenance Risk management System deficiencies Water age Water distribution Water quality and parameters Water safety plans( WSP) PA
Reference Technologies for legionella control in premise plumbing systems: scientific literature review. Republished with permission from the Environmental Protection Agency.
www. plumbingafrica. co. za April 2017 Volume 23 I Number 2