We assessed the disinfection efficacy of an
ozone generator prototype in ambulances used to transport patients with coronavirus disease (COVID-19). This research consisted of three stages: in vitro tests using microbial indicators, such as Candida albicans, Escherichia coli, Staphylococcus aureus and Salmonella phage, which were experimentally inoculated onto
polystyrene crystal surfaces within a 23 m3 enclosure. They were then exposed to
ozone at a 25 ppm concentration using the
ozone generator (Tecnofood SAC) portable prototype, and the decimal reduction time (D) was estimated for each
indicator. The second stage involved the experimental inoculation of the same microbial indicators on a variety of surfaces inside conventional ambulances. The third stage consisted of exploratory field testing in ambulances used to transport patients with suspected
COVID-19. During the second and third stages, samples were collected by swabbing different surfaces before and after 25 ppm ozonisation for 30 min. Results suggested that
ozone was most effective on Candida albicans (D = 2.65 min), followed by Escherichia coli (D = 3.14 min), Salmonella phage (D = 5.01 min) and Staphylococcus aureus (D = 5.40 min). Up to 5% of the microbes survived following ozonisation of conventional ambulances. Of the 126 surface samples collected from ambulances transporting patients with
COVID-19, 7 were positive (5.6%) for SARS-related coronavirus as determined on reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR).
Ozone exposure from the
ozone generator prototype inside ambulances at a concentration of 25 ppm for 30 min can eliminate gram positive and negative bacteria, yeasts, and viruses.