Applied and Environmental Microbiology, Dec. 1982, Vol.44, No.6, p.1330-1334.
Infectious Disease Section, Research and Medical Service,
Veterans Administration Wadsworth Medical
Received 7 April 1982/Accepted 5 August 1982

The effect of ozonation of supply water for one wing of an unoccupied hospital
building which had positive cultures for Legionella pneumophila from multiple
potable water fixtures was studied in a prospective, controlled fashion. Mean
ozone residual concentrations of 0.79 mg/liter eradicated L. pneumophila from the fixtures, but so did nonozonated water in the control wing fixtures. The efficacy of the nonozonated water was most probably due to a mechanical flushing effect and to an unexpected rise in the chlorine content of the supply water. Determination of the in vitro activity of ozone against L. pneumophila did not predict the efficacy of its eradication from water fixtures treated with ozone.
Paul H.Edelstein, R.E.Whittaker, R.L.Kreiling, Clifford L.Howell