LEGIONELLA - World Health Organization

9.4.4 Concrete batcher process on a construction site — UK
This section is based on a case study submitted by SB Surman-Lee, C Seng and T Harrison,
of the Health Protection Agency, London, UK.
Untreated warm water and high pressure aerosols are high-risk factors for causing Legionnaires’
disease. Aggregate (used in making concrete) stored outside in winter in the UK is too cold
for production of some concrete mixes. A case of Legionnaires’ disease was found in a construction
site worker. The person was working near a concrete batching plant where warm water (about
30 ºC) was added to a concrete batcher to facilitate the chemical process during cold weather.
The untreated warm water source was a storage tank containing borehole water, heated by an
adjacent boiler.
A powered jet washer connected into the warm water supply was used to hose down and remove
concrete from the batcher plant, surrounding areas and lorries. Water from the storage tank,
associated pipework and jet washer had high levels of Legionella pneumophila serogroup 1
(>105 CFU/litre). Isolates obtained from the patient and the environmental sources were
found to be indistinguishable by further typing from L. pneumophila serogroup 1, MAb
subgroup “Knoxville”, SBT 3,10,1,10,14,9.
This is the first time that a case of Legionnaires’ disease has been associated with concrete
production on a construction site. The site workers believe that similar systems operate elsewhere.
This case therefore highlights the need for a thorough risk assessment of all systems using
water on construction sites worldwide, and the need for systems to manage and control warm
water used in similar processes.
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS