Panasonic is the first in the industry*¹ to verify the inhibition of airborne and adhered bacteria in a real-world space by using hypochlorous acid

Osaka, Japan, January 16, 2025 - Panasonic Corporation today announced that its Heating & Ventilation A/C Company (HVAC Company) is the first in the industry*¹ to verify the inhibition of airborne and adhered bacteria in a real-world space by using hypochlorous acid*² jointly with Gunma Paz University. The company will continue to promote industry-academia collaboration and conduct research with the aim of achieving the further advancement of hypochlorous acid technology and creating a space that reduces the risk of bacterial and viral infection.

In recent years, as outbreaks of various infectious diseases, such as influenza, COVID-19, and mycoplasma pneumonia, have been identified, the HVAC Company has confirmed the inhibition of several bacteria and viruses, including influenza and COVID-19, using hypochlorous acid. For over 30 years, the company has been studying hypochlorous acid,*³ which proved to be highly effective in bacterial and viral inhibition and deodorization. Moreover, in April 2022, the IAQ Verification Center was established in Kasugai City, Aichi Prefecture, as a facility for conducting more advanced verifications related to hypochlorous acid, to further enhance the company's research system.

In order to verify the effects of hypochlorous acid on controlling human infection, in addition to the accumulated evidence of inhibiting bacterial and viral growth, the HVAC Company has launched industry-academia collaboration with Gunma Paz University, which focuses on medical studies. The university's Advanced Medical Science Research Center promotes pioneering medical science studies. It consistently conducts important research fundamental to diagnosing and treating virus infectious diseases such as the development of new testing and diagnostic methods, and carries out studies related to infection control within hospitals and facilities and cause investigation.

The current testing used a real-world space for the first time in the industry,*¹ classrooms and a laboratory at Gunma Paz University, to verify the inhibition of airborne and adhered bacteria in the rooms by using hypochlorous acid. To test airborne bacteria, students took classes in two different classrooms, each about 115 m² in size, where ventilation was provided, and the air conditioner was running. Verification devices equipped with a dust collecting filter and the function to generate the hypochlorous acid solution within the devices were placed in one room. The devices were operated 24 hours a day for five days, from Monday to Friday, while the university was open. Airborne bacteria were sampled on Tuesday during the lunch period and following afternoon classes. Consequently, the company confirmed a reduction in bacteria by approximately 85% in the classroom with verification devices. Furthermore, it identified airborne bacteria inside the classroom, detecting fungi and various other bacteria, including mold, Bacillus species, and Staphylococcus aureus. This indicates that the devices equipped with the hypochlorous acid generation function and dust collecting filter are effective against a wide range of airborne bacteria.
With regard to adhered bacteria, a petri dish with Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus adhered was placed 8 meters away from the verification devices mentioned above in an empty laboratory of about 93 m², with ventilation and the air conditioner running. After 24 hours of testing, the company confirmed a 99.9% reduction in Staphylococcus aureus compared to a room without verification devices (natural attenuation), using the hypochlorous acid solution generated within devices and then gasified.

Concerning the current research results, Professor Hirokazu Kimura, Infection Control Doctor of Gunma Paz University, stated, "I will continue testing the inhibition of bacteria and viruses in a real-world space and evaluating the prevalence rate, and look forward to a future where the use of hypochlorous acid technology proves effective in reducing infection risks." Panasonic will engage in research on hypochlorous acid technology to create an infection-controlled space, where people can live with a sense of security and safety.

Notes:
*1: With respect to the verification of the inhibition of airborne and adhered bacteria in a real-world space. In Japan's air purification and air conditioning industry. As of January 16, 2025, according to Panasonic's research.
*2: These verifications were conducted for basic research purposes and did not involve any products containing the hypochlorous acid solution.
*3: Including SANYO Electric Co. Ltd.

■Verification method
Four verification devices were placed in each of the two classrooms at Gunma Paz University, where classes were held. The inhibition of airborne bacteria was verified by comparing verification devices with the hypochlorous acid generation function and those without it (natural attenuation). A verification test was also conducted to compare verification devices with and without the dust collecting filter mounted on the air inlet.
Gram stains were performed on sampled bacteria to identify falling airborne bacteria.

■Verification results
Verification devices with the hypochlorous acid generation function and dust collecting filter demonstrated a significant difference, with an approximate 85% reduction in airborne bacteria.
Verification devices without the hypochlorous acid generation function but with the dust collecting filter demonstrated a significant difference, with an approximate 50% reduction in airborne bacteria. (Figure 1)
Moreover, as a result of Gram staining of the sampled bacteria, fungi and various other bacteria were detected, including mold, Bacillus species, and Staphylococcus aureus. (Figure 2)

Testing organization: Panasonic Corporation
Verifying organization: Gunma Paz University

●Verification device: Four verification devices were placed, with a rotary inhibition filter inserted after being soaked in a hypochlorous acid solution of approximately 100 mg/L and exposed to a specified airflow (5.6 m³/min), and a dust collecting filter mounted on the air inlet.
●Verification method
- Operation of verification devices: 24 hours a day from Monday to Friday
- Verification device conditions*⁴: Hypochlorous acid (+) & dust collecting filter (+), hypochlorous acid (-) & dust collecting filter (+), hypochlorous acid (-) & dust collecting filter (-) [natural attenuation]
- Test environment
University classroom: Approximately 322 m³, with ventilation and air conditioning (Figure 3)

[Sampling of airborne bacteria]
- Hypochlorous acid (+) & dust collecting filter (+), hypochlorous acid (-) & dust collecting filter (-): Collect airborne bacteria in the classroom by drawing 500 L of air in 5 minutes using an air sampler with a petri dish containing blood agar, at the onset of testing, and after 2.25 and 4.25 hours.
- Hypochlorous acid (-) & dust collecting filter (+): Collect airborne bacteria in the classroom by drawing 200 L of air in 2 minutes using an air sampler with a petri dish containing blood agar, at the onset of testing, and after 3.75 and 5.75 hours.
- Air sampler installation position: Place the air sampler 2.3 m away from verification devices (0.7 m above the floor).

[Measurement of bacteria]
The petri dish was collected at each predetermined time and was placed in an incubator for about 48 hours. Colonies were counted, and a significant difference in the bacterial reduction rate was identified using the Tukey statistical method.
[Bacterial identification through Gram stains]
- After several types of bacteria were extracted from the collected petri dish containing blood agar and Gram stains were performed, they were observed under a microscope for identification.

Notes:
*4: Hypochlorous acid (+): Electrolytically generated, Hypochlorous acid (-): No electrolysis, Dust collecting filter (+): Mounted, Dust collecting filter (-): Not mounted

Testing organization: Panasonic Corporation
Verifying organization: Gunma Paz University

●Verification device: Two verification devices were placed, with a rotary inhibition filter inserted after being soaked in a hypochlorous acid solution of approximately 30 mg/L and exposed to a specified airflow (5.6 m³/min) to volatilize the active chlorine component.
●Verification method
- Verification device conditions*⁵: Hypochlorous acid (+), hypochlorous acid (-) [natural attenuation]
- Test duration: 24 hours
- Bacterial adhesion method
Drop 50 μL of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus bacterial liquids in a petri dish and dry them.
- Test environment
Hypochlorous acid (+): University laboratory, approximately 260 m³, with ventilation and air conditioning (Figure 5)
Hypochlorous acid (-): Inside the safety cabinet
- Petri dish placement
Hypochlorous acid (+): Place a petri dish 8 m away from verification devices (0.8 m above the floor).
Hypochlorous acid (-): Place a petri dish inside the safety cabinet.

[Measurement of bacteria]
The bacteria-adhered petri dish was collected 24 hours after its placement. Considering the liquid used to wash the dish as an undiluted test solution, it was serially diluted to 10 levels. The undiluted or diluted solution was sampled on a petri film, which was placed in an incubator for 24 to 48 hours. Colonies were counted, and a significant difference in the bacterial reduction rate was identified using the Mann–Whitney U test statistical method.

Notes:
*5: Hypochlorous acid (+): With the placement of verification devices, Hypochlorous acid (-): Without the placement of verification devices

* These verifications provide the results of Panasonic's technology research or information on ongoing projects, and do not demonstrate the effects of products.