Airborne diseases are recognised by the World Health Organisation (WHO) to be among the top ten causes of death and have caused numerous pandemic outbreak in recent years. Having suffered under Severe Acute Respiratory Syndrome (SARS) in 2002 and H1N1 influenza pandemic in 2009, the public gained attention at effective air sterilization methods. Various air disinfection units such as ionizers and ozone-generating purifiers emerge as successful commercial products. However, these purifiers are energy-intensive and poses potential health concerns caused by ozone generation. Although alternatives such as high quality air filters can effectively remove bioaerosols from the air stream, trapped microbes continue to aggregate and populate on the filter surface during the filtration process and eventually results in filter degradation and penetration. Microbe populated filters can lead to subsequent volatile organic compounds (VOCs) release and become the source of pathogenic recontamination.
This work reports on a multilevel antimicrobial filtration system that employ the use of controlled-release antimicrobial coating applied on particulate air filters. Gaseous biocide, chlorine dioxide, was encapsulated and control-released for sustained “release-killing”. “Contact-killing” and “anti-adhesion” were also engineered into the encapsulating shell by the use of catalytic-dyad and detergent polymers. After the antimicrobial coating was incorporated into two types of particulate air filters (i.e., HVAC and HEPA), the “release-killing”, “contact-killing” and “anti-adhesion” properties of the new multilevel antimicrobial particulate air filters were individually investigated against Gram-positive and Gram-negative bacteria, bacteria endospores and fungal spores. Accelerated life test indicates the antimicrobial particulate air filter has an operation life of at least 12 months. Better than two log bacterial reduction was also observed for ten minutes contact test.