Abstract
ABSTRACTCurrently silver nanoparticles (AgNP)-modified filter are widely used to inactivate airborne microbes in indoor environment. However, AgNP is extremely small and thus will penetrate cells membranes to cause cytotoxicity. AgNPs/NSP has been proven to be less cytotoxic to human body. In this study, it was the first time that AgNPs/NSP was used to develop a new antimicrobial air filter with low cytotoxicity. The AgNPs/NSP filter was made by dip-coating of filter with AgNPs/NSP and acrylic resin solution and three different amount of silver on filter were obtained including 12.6, 31.5 and 63 ppm. The filtration efficiency and the antimicrobial activity of AgNP/NSP filter were evaluated by bioaerosols including Escherichia coli and Candida famata in testing chamber and HVAC simulation system under 30% and 70% relative humidity (RH). The results showed that filtration efficiency of AgNPs/NSP-modified filter increased by about 13 to 20% compared to unmodified filter for E. coli but remained almost the same for C. famata. The antimicrobial efficiency of AgNPs/NSP modified filter of 63 ppm was 95.1% for E. coli at RH of 30%. In addition, 91% of antimicrobial efficiency for C. famata was found at RH of 70%. On the other hand, the antimicrobial efficiency of yeast for AgNPs/NSP-modified filter was 97.8% and 86.4% for RH of 30% and 70% respectively when yeast just started to contact with filter in HVAC system. The results suggest that AgNP/NSP-modified air filter can effectively inactivate microorganisms retained on. Therefore, emission of bioaerosols from air filter can be avoided in order to improve the air cleaning technology in indoor environment.
Highlights
IntroductionPeople with exposure to bioaerosols may get acute pulmonary and respiratory diseases (Peccia et al, 2008)
Bioaerosols have been shown to have adverse effects to human health
The results showed that filtration efficiency of AgNPs/nanosilicate platelet (NSP)-modified filter increased by about 13 to 20% compared to unmodified filter for E. coli but remained almost the same for C. famata
Summary
People with exposure to bioaerosols may get acute pulmonary and respiratory diseases (Peccia et al, 2008). The outbreak of severe acute respiratory syndrome (SARS) in 2003 and H1N1 pandemic in 2009 prompted high attention to bioaerosols. Filtration, which can remove particulate matter and bioaerosols simultaneously, is widely used in air purifiers to improve indoor air quality (Lee, 2011). Silver nanoparticle (AgNP) is one of the most prevalent antimicrobials because it is relatively less toxic and environmentally friendly (Windler et al, 2013) and has been widely used in commercial silver coated filters. The silver coated air filters could still potentially release AgNPs into air while using (Quadros and Marr, 2010). Due to its nanoscale size (1–100 nm), AgNPs may penetrate cell membranes and accumulate in cells, which may cause cytotoxicity and genotoxicity
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