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Experts respond to New York legionella outbreak

With the Legionnaires’ disease outbreak in New York making headlines around the world, H&V News asked speakers at the upcoming Combating Legionella and Water Treatment conference for their comments.

What are the basics of global best practice on risk assessment of cooling towers?

SETRI Consultoria em Sustentabilidade, Brazil, technical director Fernando Henrique Bensoussan replied that legionellosis outbreaks around the world are, in most cases, associated with cooling towers.

“And it is common to think that laboratory analysis and risk evaluation suffice to prevent risks in that area,” he said.

“However, from my experience in field I can say that one of the most challenging hazards to identify is the true concern of the person in charge.

“Some may request a report only to have it archived, and others may really worry about risks to which they can be exposing people.”

He added: “If there is no concern in that regard, there will probably be no interest in a genuine validation.  No risk management should be based only in laboratory analysis.”

What should duty holders and cooling tower operators do to prevent Legionella contamination?

Hartlepool Borough Council Legionella team leader Ian E Kershaw said: “The Legionnaires’ disease outbreak in New York has once again highlighted the risk from legionella bacteria in the built environment.

“We know that any water system, subject to the right conditions, can cause a serious threat and therefore good control is essential. The ACoP L8 and the associated HSG274 Parts 1-3, although key here in the UK, form part of the many reference documents available.

He continued: “Of course, we also have the vast resource of the internet along with networking applications such as LinkedIn.

“You can harness a huge amount of information and advice from many recognised experts in the field of legionella and at no cost to your organisation and I would urge you to use it.”

Speaking on behalf of the Water Management Society Technical Committee David Bebbington CSci, CChem, MRSC, FWMSoc said cooling tower systems can be complex and vary widely in design.

“They can infect large numbers of people – many of whom may be susceptible – should they become infected with legionella,” said Mr Bebbington.

“The most important factor, therefore, is that the risk assessor be competent to carry out the work on this type of system.

He added: “They are likely to have had practical experience in dosing and control of a wide range of industrial cooling systems, as well as formal training, in order to have gained this knowledge.

“They must know their limitations and be prepared to ask for help – especially when assessing systems associated with processes and production, as occasionally cooling water comes into contact with the product.”

Mr Bebbington said the structure of the risk assessment for cooling towers is as follows:

  1. Identify the hazard.
  2. Assess the risk.
  3. Advise on elimination of the system or substitution for a lower risk system if possible, otherwise:
  • Reduce the risk to as low as is reasonably practicable by control and management.
  • Ensure the management of the system is robust (keeps the controls in place), is responsible, accountable and covers for absences.
  • Advise on monitoring, testing and inspections of the system.
  • Check records of all test results and actions.
  • Review on a regular basis.

The 12th Annual Combatting Legionella & Water Treatment conference will take place on 29-30 September at Aston Villa Park in Birmingham.