Modern history has proven that airborne respiratory infections are not to be underestimated. Now, a new sprayable coating applied to standard air filters may give us an edge in the fight against the pathogens that cause these illnesses.
Measles, influenza, SARS, MERS... whenever you think of a major infectious disease, it is likely to be an airborne pathogen. Currently, COVID-19 and tuberculosis are the world’s deadliest infectious diseases, and both diseases are airborne. Therefore, to reduce the risk of disease spreading among the population, it is paramount to develop solutions that can remove infectious germs from the air.
So researchers in Spain teamed up with Spanish air filter manufacturer Venfilter to investigate whether a spray-on coating could improve the disease resistance of commercially available air filters.
The team tried three metal compounds: silver oxide, copper oxide and zinc oxide. They each created a spray containing nanoparticles of these compounds and sprayed it on the filter. They found that both silver oxide and copper oxide sprays had over 99% antiviral activity, with silver oxide spray also completely preventing bacterial growth within 24 hours of the study. They also found that the spray did not affect the filter's ability to properly remove other particles from the air.
Most encouragingly, the authors found that both the AgO and CuO complexes used had complete antiviral activity (greater than 99%), with the AgO filter extract also completely preventing the growth of the target bacteria during the 24-hour incubation period measured in the study.
The researchers believe the coating could be effective against a variety of airborne pathogens, but in this study they focused on two in particular: Streptococcus pneumoniae and Pseudomonas aeruginosa.
"Diplococcus pneumoniae and Pseudomonas aeruginosa are considered to be among the top five bacterial pathogens causing death worldwide," said study co-author Mónica Echeverry-Rendón. "Streptococcus pneumoniae is a major causative agent of community-acquired bacterial pneumonia, acute otitis media in children, and non-epidemic meningitis. Pseudomonas aeruginosa is often associated with recurrent exacerbations of chronic infections in patients with cystic fibrosis and bronchiectasis."
We’ve seen the antiviral effects of metal oxides in bioactive glass and heat-activated procedures designed to disrupt biofilms, as well as a light-activated foil used to improve the effectiveness of HEPA air filters in destroying harmful bacteria. As with these advanced technologies, new spray coatings require further development before they can be put into commercial use.
"While the achievements achieved so far are significant at a scientific level, there is still a long way to go before commercialization at an industrial level," said Echeverry-Rendón. "Different aspects need to be considered in future work and further testing... to enable a full characterization of the coating effect and filter performance over time using real-size filter prototypes with sealing frames."
The current research is published in the journal Chemistry and Physics of Materials.