The Legionnaires' outbreak is said to have huddled around Heads of the Valleys corridor and there are at present 11 people being linked to the disease. These people are among the 13 people in south Wales who are being treated for the disease.

While the health officials have been focusing mainly on the industrial premises, some of them believe that large scale air conditioning systems too can be the source of this infection.

All this research by the Health officials is subsequent to the death of a 64-year-old woman on Monday, though it has yet not been established that the cause of her death was Legionnaires' disease.

Jonathan Richards, a GP in Methyr Tydfil has asserted that since there was no tangible source, it was very difficult to confirm that the death was due to the disease.

Dr. Brendan Mason, consultant epidemiologist for PHW said that they were very busy figuring out the reason behind the infection, so that they could save all the ones who were at a potential risk of the disease. Presently, the Public Health Wales, the Health and Safety Executive are busy inspecting the seven council areas.

“You are then looking at sources like cooling towers that under the right atmospheric conditions can disseminate this organism over very wide areas, many miles in fact”, he added.