BSRIA Legionella Guidance 2015

BSRIA legionella guide cover 2015

BSRIA legionella guide 2015

BSRIA has published a FREE Legionella topic guide in PDF format here is the (LINK) to download from the BSRIA website.

In fact I had the pleasure of meeting BSRIA’s Tom Jones during his recent trip to Hong Kong in October 2015.

John A. Herbert

Mr John A. Herbert (left) and Tom Jones at Eco Expo Asia Hong Kong 2015

BSRIA has also published a topic guide for building air tightness (LINK) to download from the BSRIA website.

by John A. Herbert

 

Hong Kong Baptist Hospital Legionella Discovered April 2015

Legionella Risk assessment Hong Kong

A 60 year male patient attending Hong Kong Baptist Hospital (HKBH) contracted a nosocomial infection, the potentially fatal Legionnaires Disease (LD). After the patient was diagnosed, EMSD sampled from both his home and the hospital. His home was negative, but the hospital water supply tested positive, four samples with Legionella pneumophila serogroup 1 (Lp1) with 0.3 to 2.3 colony-forming units per millilitre (cfu/ml) reported. {1}.

Remember the infectious dose for LD is still unknown, but could be as little as 1 cfu based on a case where Legionella was contracted 6 km away from the source.

The HKBH fresh (potable) water tank was reported negative for Lp1. Since the fresh water tank in an ‘occupied’ hospital would typically have a high turnover, a negative result would be expected because there is little risk of stagnant water. Therefore, in this case the root cause must be within the water distribution piping.

Interestedly, three environment swabs, collected from HKBH, also tested positive for Lp1, but as usual no details were reported. We can only speculate these could be swabs from surfaces in and around the shower and toilets areas.

Approximately month after first exposure, around 4 April 2015, it is reported that the EMSD visited the site today, presumably the date of the government press release 5 May 2015 {1} , recommending I quote ‘….disinfection of the relevant water system.’ amongst other measures. The number of patients who may have been exposed to the risk of contracting Legionella during that month is unknown, and attempting to disinfect the water system in a working hospital full of patients will be a challenge. In the report there is no mention of any earlier risk assessment.

This case is particularly troubling because Legionnaires Disease (LD) was contracted in the hospital environment, and it seems from the report that approx. one month lapsed between infection and disinfection.

[1] http://www.chp.gov.hk/en/view_content/39502.html

Poorly Maintained AC is a Health Hazard

As the mercury hovers above 30 Deg C buzzing air conditioning units working overtime are commonplace in street and offices across the city.  And if you’re a facility operator or business owner you also need to ensure that the air conditioning system is properly maintained, not only to maintain energy efficiency but also to prevent spreading disease. If we had a Legionella threat level it would now be ORANGE!

Air conditioning systems are a documented source of Legionella [1], the system has all the necessary elements, the capacity to harbour, breed, and distribute Legionella into the air we breathe. Microscopic water droplets contaminated with Legionella can be easily inhaled, risking the potentially fatal Legionnaires disease infection.

Legionella comes from nature, its found at low concentrations in lakes, streams, and groundwater. Also one type thrives in compost and soil.  Legionella escapes conventional water treatment and low concentrations are piped into our buildings, given the right conditions Legionella can proliferate and then your problems begin.

Since the infection dose is small, and the incubation period is 7-10 days, you can see that just one contaminated cooling tower is a risk, and might expose thousands of people, before the first infected person seeks medical attention, that is how an outbreak occurs.

The EMSD Code of Practice for the control of Legionella [link] places the emphasis firmly on the business and owner to identify and assess any risk, and then act to minimise that risk, however many firms lack the expertise and need to contract this work to specialist consultant like Kelcroft [link]

Regular auditing of air conditioning systems lowers the risk of spreading disease than those left unattended. Thankfully, we now have simple tests that can detect the presence of bacteria, and they should be performed in addition to regular maintenance.

Buildings using WCAS (water cooled air conditioning systems) have devices called cooling towers used to reject the waste heat heat to atmosphere, using water, and these type of systems have been identified by government as a specific threat, and mandates that the owner must conduct an independent third party annual audit report and submit to EMSD every year.

Understand Legionella is important, I visited a industrial facility last year and found a heat recovery system with all the elements.  The system pre-heated fresh water, stored the warm water at the prefect temperature for Legionella breeding and growth then pumped the warm water across the factory to distant spray-heads –  a preventable outbreak waiting to happen!

— John A Herbert, Consultant, Kelcroft E&M Limited

[1] Note also other misting devices have been documented to harbour and spread Legionella, including but not limited to, decorative fountains, machinery coolant, hot water systems, heat recovery systems, showers, misting cabinets, spa baths, and humidifiers.