Seoul Viosys says through air purifier and air steriliser filters, bacterial growth and leakage occur
Ansan, South Korea – Seoul Viosys, a global optical semiconductor company, conducted a test on air sterilisation by air purifiers sold in the market. The test confirms that bacterial growth and its leakage occur through the filters. The company announced filters in air purifiers and air sterilisers can cause viral infection and virus spread.
The company commissioned a research institute K, an internationally certified testing and research institute, to conduct a ‘test on bacterial residue count’ to check how many germs remain within filters. Air purifiers sold in the market were randomly selected and the filter contamination level was checked. For one gram of filter, an average of 70 CFU (colony forming unit) was confirmed, and for yeast and mold, more than 300 CFU per gram. These numbers are three times higher than the bacteria-permissible level, 100 CFU/g, in wet tissues under the current Cosmetics Act of Korea.
In general, air purifier filters need to be replaced, on a regular basis, every 6 months or every year, as the capture performance of filters is compromised due to suspended particles such as captured dust. According to a thesis on the survival period of harmful bacteria in filters (survival of microorganisms on HEPA filters. James T. Walker et al., Applied Biosafety Vol. 16, No. 3, 2011), it has been confirmed that Staphylococcus epidermidis which causes vomiting, stomachache, and diarrhea can live up to five days in filters, and Bacillus atrophaeus can survive for more than 6 days up to 210 days at maximum.
The bioresearch team of the company checked bacterial residue inside filters, and then based on the outcome, the team also conducted a ‘virus filtration test (virus passage test).’ After spraying ‘Phi X 174’ virus which is similar to the Covid-19 virus in size and features at a chamber of 60 m3, air purifiers from company A, B, and C were operated for 10 minutes, respectively. Then, the virus level was measured around the purifier’s outlet area, and virus level was confirmed at 0.005~0.01% compared to the sprayed virus concentration in the air. One virus can multiply up to 1 million to 100 million times at maximum in 5~6 hours, and even if air purifier filter is used, 10,000 viruses, amounting to 0.01%, may not be filtered and may disperse into the air. Usually, as a small number of viruses such as 1,000 flu (influenza) viruses and 10~100 Noroviruses can cause infection, a sterilisation system to prevent any micro leakage is required. It has been measured that one droplet of a Covid-19 patient contains 100-1,000 viruses at maximum.
Young Ju Lee, CEO of Seoul Viosys Co., Ltd., says “Through this test, it has been confirmed that as time goes by, filters can even work as a medium of bacteria growth, and viruses that pass the filter can spread the infection. Filters alone cannot prevent bacterial infection and sterilisation will be the best way for disinfection.”
With its dedication to UV LED technology development for the last 20 years, the company has developed a clean sterilisation technology, ‘Violeds.’ As part of the activities to prevent the spread of infection through the air, in 2020, the company has provided ‘air sterilisers’ for free in 300 SOHO business sites in Korea that combine filters with ‘Violeds’ technology, developed based on the investment of KRW one billion. According to a phone survey on its users in December 2022, 92% of respondents were found to be satisfied, and 83% said they would recommend the product to others, showing that the level of satisfaction with the product is quite high.
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