Recommended Treatment Levels of Ozone For Particular Microbial Species Note: The CT factor is the product of the ozone concentration and the contact time in minutes. Essentially, the  higher the CT factor, the more difficult the organism is to kill. Note also that a microbial species with a CT factor  of 0.01 for example will be killed by an ozone concentration of 0.01 mg/L end a contact time of 1.0 minutes, or  an  ozone concentration of 1.0 mg/L for 0.01 minutes, (0.6 seconds), e.g., the case with Staphylococcus aureus. -  Similarly, 2.0 mg/L ozone, in the case of Staphylococcus will produce a CT factor of 0.01 in 0.005 minutes, or  0.30 seconds.  ORGANISM mg/O₃/L Minutes CT Algae (blue green) 0.30 5.0 1.5 Bacteria (all species), recommended 0.10 1.0 0.1 Aeromonas & Actinomycetes yes Bacillus_, all yes Campylobacters yes Clostridium Botulinum & others yes Escherichia coli (E. coli) 0.04 1.0 0.04 coliphage MS2 0.20 0.5 0.1 Flavobacterium yes Helicobacter (pylori) yes Heterotrophic Bacteria,- HPC 0.20 .5 0.1 Leqionella pneumophlia yes Micrococcus, all yes Mycobacterium tuberculosis, leprae 0.01 6.0 0.06 Pseudomonas aeruginosa, fluorescens 0.01 1.0 0.01 Salmonella, all 0.01 1.0 0.01 Shigella shigellosis dysentery yes Staphylococcus sp, albus, aureus 0.01 1.0 0.01 Streptococcus all 0.01 2.0 0.02 Vibrio: aiginolyticus, anguillarium yes     cholerae, comma, parahemolyticus yes Yersinia enterocolitica yes Fungus, Molds, Yeasts 0.3 5.0 1.5 Mold Spores 0.03-0.30 Nematodes, all, recommended 1.0 5.0 5.0 Hook worm & etc. 0.3 Protozoa. all, recommended 1.5 5.0 7.5 Acanthamoeba & Naegleria 0.2 0.5 0.1 Amoeboe Trophozoites cysts 0.4 4.0 1.6 Cryptosporidium_,  recommended 1.5 5.0 7.5 Cyclospora yes Entamoebea (histolytica) yes. Giardia lamblia 0.8 5.0 4.0 Giardia muris 0.50 5.0 2.5 Microsporidium yes N. gruberi 0.50 5.0 2.5 Trematodes, all, recommended 1.0 5.0 5.0 Flat worms, flukes & etc. 0.3 VIRUS, all,  recommended 0.40 4.0 1.6 Adenovirus, 7A 0.30 3.0 0.9 Astrovirus yes Calicivirus yes Echovirus 5,12 & 29 0.40 4.0 1.2 Encephalomyocarditis yes Enterovirus, over 35 types 0.30                       4.0                         1.2 coxsachie, B3 & B5            0.60                      1.0                         0.6 poliovirus, 1, 2 & 3 0.30                        4.0                        1.2 Hepatitis, A E & HAV yes nonA and nonB yes Myxovirus Influenza yes Norwalk yes Picobimavirus yes Reovirus 3 types, yes Rotavirus, 3 types                                                         yes Information written for the Drinking Water Unit of EPA’s Region 10 by Jim Eagleton.