Authors: Le Hoang Tu, Le Hoang Oanh, Nguyen Vu Trung, Le Cao Cuong, Doan Thi Yen Oanh, Tran Vinh Dieu, Nguyen Hoang Nghi
Affiliations:
- Ha Dong General Hospital, Ha Dong, Hanoi, Vietnam
- Hanoi University of Science and Technology, Hanoi, Vietnam
- Publishing House for Science and Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Submitted: March 20, 2020
Accepted: May 17, 2020
Abstract
Healthcare-associated infections (HAIs) affect hundreds of millions of patients globally each year, leading to significant mortality and financial losses. Contaminated surfaces and air in hospitals are critical vectors for the transmission of respiratory pathogens. Recently, ozone disinfection has emerged as an effective alternative to conventional disinfectants, significantly reducing microbial contamination in hospital air and surfaces. This study investigates the disinfection capacity of ozone gas by analyzing colony-forming unit (CFU) reduction during ozonation of an operative theatre at Ha Dong Polyclinic Hospital in Hanoi, Vietnam. The complete removal of microorganisms and fungi was achieved with an ozone concentration of 5 ppm and an exposure time of 40-60 minutes.
Introduction
Hospital-acquired infections are a prevalent issue worldwide, with hundreds of millions of patients affected each year. The transmission of respiratory pathogens in clinical settings is often facilitated by contaminated surfaces, such as bed sheets and towels, and through airborne particles. Therefore, effective air disinfection techniques are essential to minimize the risk of HAIs. Traditional methods like UV radiation and HEPA filters have limitations, prompting the exploration of ozone as a powerful oxidizer for air and surface disinfection.
Materials and Methods
Experiments were conducted in a 30 sq. meter operative theatre at Ha Dong Polyclinic Hospital. An ozone generator with a capacity of 25 grams per hour was used to achieve an ozone concentration of 5 ppm, with exposure times ranging from 20 to 60 minutes. The disinfection process was monitored using ozone monitors and electronic systems to ensure uniform distribution and control of ozone levels. Two experimental variants were tested: a static variant with no air addition post-ozonation, and a dynamic variant with fresh air added through a HEPA filter.
- Static Variant: Ozone levels maintained at 5 ppm for 20-60 minutes, followed by thermal decomposition and Petri dish exposure.
- Dynamic Variant: Fresh air introduced post-ozonation, reducing ozone levels to 0.1 ppm, followed by Petri dish exposure.
Petri dishes were placed in the room, incubated, and analyzed for CFU counts to assess microbial reduction.
Results and Discussion
The study demonstrated a significant reduction in CFU in both static and dynamic variants, with a higher effectiveness observed in the static variant. In the static experiment, CFU decreased from nearly 500 to zero after 60 minutes at 5 ppm. The dynamic variant showed a CFU reduction from 500 to 64, indicating that the introduction of fresh air post-ozonation reduced the overall effectiveness.
Ozone was effective in disinfecting both airborne microorganisms and those on surfaces, including walls, ceilings, floors, and equipment. The study highlighted the potential of ozone as a powerful and environmentally friendly disinfectant, leaving no toxic residues.
Conclusions
- Ozone effectively eliminates microorganisms and fungi in hospital environments at 5 ppm concentration with a 30-60 minute exposure.
- Ozone disinfection targets both airborne and surface-bound microorganisms, providing comprehensive decontamination.
- The static variant of ozone treatment, without the addition of fresh air, is more effective than the dynamic variant with HEPA filters.
- Ozone, combined with HEPA filters, offers a high-efficiency air disinfection method, ensuring safe and clean hospital environments.
This study underscores the potential of ozone disinfection as a superior alternative to conventional methods, offering significant benefits for hospital hygiene and patient safety.
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