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Q&A: City of London environmental health officer discusses legionella

H&V News spoke to City of London environmental health officer Toby Thorp about legionella contamination following the recent outbreaks in America and the UK.

In August, an outbreak traced to the Opera House Hotel in New York killed 12 people and sickened 128 before it was declared over, while four people were also killed following a Legionnaires’ outbreak at an Illinois veterans’ home.

An outbreak was also discovered in California at the San Quentin Prison, which sickened at least five inmates and left dozens under observation; and a UK-based steel coating company has recently been fined for failing to manage the risks from legionella bacteria at two cooling towers over a period of five years.

Following these events, H&V News questioned Mr Thorp about avoiding, containing and managing legionella outbreaks.

What are the main issues behind the ongoing problems with cooling towers and their association with legionella contamination?

We all know that contamination is essentially unavoidable in any man-made water system. What I think is oft forgotten, or maybe unrealised, is how little time it takes legionella to proliferate in an ideal environment. It’s rare to find an ideal environment in the real world, but the systems that come closest are surely uncontrolled cooling towers.

Good design can eliminate so many risk factors for legionella growth at the start of a system’s life, and this is why it is so very frustrating for us as regulators to come across problems in newly installed towers. Often it appears that various project teams have simply failed to effectively communicate – whether that be failing to adequately plan for maintenance requirements, for example space and access around a tower, or failing to convince clients that value engineering a tower down to the lowest point is false economy. 

Its invariably difficult and arguably inappropriate to pinpoint where “blame” may lie in design failure, but rushing passivation of towers using the cheapest materials possible and installing baffles and ducting above a tower so the pack can never be removed are all significant issues for the long-term management of legionella in a cooling system.

How can awareness of this be improved?

Given the local prevalence of towers, we do our best at the City of London to intervene early with architects and designers where we suspect a tower will be installed – but that has surprisingly limited effect. Health and safety is not a statutory consultee for planning, and our enforcement powers don’t come into effect until after the event. The construction phase is almost certainly under the enforcement remit of the Health and Safety Executive (HSE) and, on a large building project, future legionella control will likely take a back seat to safety matters during any enforcement visit.

The truth is that those in the best place to make arguments for better design and appropriate resourcing at installation are those undertaking the work. Also, in making an effort to go a step or two higher in the communication chain to where the decisions are really being made.

Is society justified in vilifying companies whose cooling towers are shown to contain legionella bacteria?

Contain? No, it’s inevitable. Fail to control? Yes.

There is so much guidance, information and assistance out there that we really shouldn’t be seeing outbreaks from cooling towers. It’s pretty inexcusable not to have at least basic control measures in place. 

Luckily, outbreaks remain infrequent events in the UK, but the increasingly fragmented managerial arrangements on some sites makes effectively assigning responsibility for the cooling tower harder – both for those on site and for those of us involved in regulating their practices.

I think any sort of finger pointing needs to be supported by evidence and thus it is beholden on investigators to reveal all information that is in the public interest in a timely fashion to better enable society to form the most accurate view possible.

Is there sufficient knowledge within the industry of appropriate maintenance and treatment methods?

I should hope so. It knows more than I do, but the more I learn, the more I realise I don’t know. Most sites get the same treatment chemicals and the same control systems seemingly by default and without much of an initial phase spent deciding whether that is actually appropriate or not.

Luckily enough that’s actually fine for the majority of sites, where simply re-enacting the same old means of control turns out to be okay. However, legionella is an insidious organism and won’t always follow the rules. I personally regard legionella risk assessments as being some of the most difficult to undertake in the world of day-to-day health and safety for that very reason. Is there sufficient knowledge within the industry to spot the times when the same old isn’t working and to truly investigate why? I’m less sure of that.

Should there be more stringent penalties for owners and operators of cooling towers found to be in breach of the regulations?

I think there are going to be, regardless of whether I think there should be or not. The new Sentencing Guidelines should be published by the end of 2015, bringing health and safety in line with environmental penalties. Some are talking about an increase in penalty sizes, especially for larger operators with a substantial turnover. But I do think that current penalties are not the deterrent they once were, so I welcome an increase in the proposed levels of fines.

Let’s not forget that good legionella control and an efficient cooling tower should be going hand in hand – I’ve never really understood why some operators are content to let their towers degrade – and, certainly for business-critical units, the deterrent of a Prohibition Notice is surely more of a concern than any of the current fines.

The views above are that of Toby Thorp and not necessarily those of the City of London Corporation.

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

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