Just a quick one here. Though people should not focus ONLY on pathogens in buildings it certainly seems that outbreaks of Legionella such as this one:
Legionnaires’ Disease Outbreak, Scotland: Man Dies In Edinburgh | UK News | Sky News.
could be used to call attention to the need to better understand microbiology of the built environment …
It’s worth noting that Legionella testing of cooling towers is required in the UK, and responses to trigger limits are also required by law. Penalties can be severe, but assigning responsibility when the distances over which Legionella can be dispersed via aerosol are large is of course a difficult task. While cooling towers are often assumed to be the source of Legionella outbreaks culturable legionella have also been isolated from hospital showers and potable water systems, as well as roadside puddles after a rainstorm. Unlike most other developed nations the United States does not mandate Legionella testing, and in fact voluntary guidelines are just being issued by industry groups and the CDC.
Study in Singapore in the 90s. http://www.ncbi.nlm.nih.gov/pubmed/9494658
“During the period 1986 to 1996, a total of 258 sporadic cases of community-acquired legionellosis was reported, giving a mean annual morbidity rate of 0.9 per 100,000 population.[…] Of the various occupational groups investigated, high seroprevalence rates were found in foreign construction workers (52.6%) and occupants of a building investigated for an unusual building-related illness (76.1%). Environmental surveillance of Legionella bacteria showed that 36% of cooling towers, 15% to 19% of decorative fountains and waterfalls and 2% of spa pools were positive. […]”
Along with the comment of John S. Chapman,
it seems that it will be necessary to do some microbial source tracking to really identify the source of the outbreak rather than assign it to the cooling towers.