Does an ISO 20743 activity value directly state the proportion destroyed?

Does an ISO 20743 activity value directly state the proportion destroyed?

No. ISO 20743 is a contact test on fabric, and its activity value is a difference between a treated fabric and an untreated control.

It is not an absolute count of anything destroyed, and it is not an airborne result. The textile and mask records under that standard are these. Hong Kong Metropolitan University (formerly The Open University of Hong Kong), Test Report IRITS2020007130001R3, 7 June 2021, tested a C-POLAR spunlace textile of polyester and cotton under BS EN ISO 20743:2013. Hong Kong Metropolitan University (formerly The Open University of Hong Kong), Test Report IRITS202203250001, 25 March 2022, tested a C-POLAR PP nonwoven material under BS EN ISO 20743:2013. Hong Kong Metropolitan University (formerly The Open University of Hong Kong), Test Report 20220907001, 7 September 2022, tested the white nonwoven front layer of a C-POLAR face mask sample under BS EN ISO 20743:2013. The filter-medium record is this. Textile Testing Institute – Brno (TZÚ), Test Report AZL 26/0757-02, 3 July 2026, a laboratory accredited to ISO/IEC 17025, tested a MERV 15A filter medium under ISO 20743 and ISO 18184. On that MERV 15A filter medium, the report records an antibacterial activity value A = 6.4 against Staphylococcus aureus and A = 4.4 against Klebsiella pneumoniae under ISO 20743, absorption method. An activity value is a difference against an untreated control fabric. It is not a percentage destroyed and not an airborne result. The Viruses page shows airborne virus at 1.3 m/s airflow, NanoFlashing™ beside a control, and states: “NanoFlashing™ captures the virus, and destroys it.” The Mold page shows airborne mold spores at 1.6 m/s airflow, NanoFlashing™ beside a control, and states: “NanoFlashing™ captures the mold, and destroys it.” The Mold page also states that researchers at Massachusetts General Hospital and Harvard Medical School, in a study with funding from the U.S. National Institutes of Health, tested NanoFlashing™ with more than 100 million live, dry spores driven in by fast-moving air. A result on one of those articles is not a result for another, and a contact result on fabric is not a capture result for a panel air filter in a duct.

A copy may be made available on our review of the request. Confidentiality obligations may apply to a given report.

Source: C-POLAR — Validation, https://cpolar.tech/validation/; Hong Kong Metropolitan University, Test Report IRITS2020007130001R3, 7 June 2021; Hong Kong Metropolitan University, Test Report IRITS202203250001, 25 March 2022; Hong Kong Metropolitan University, Test Report 20220907001, 7 September 2022; Textile Testing Institute – Brno (TZÚ), Test Report AZL 26/0757-02, 3 July 2026; C-POLAR — Viruses, https://cpolar.tech/contaminants/viruses/; C-POLAR — Mold, https://cpolar.tech/contaminants/mold/.

Reviewed on 21 September 2026.