Antimicrobial filters could improve the safety of travellers

18 March 2022 | Muriel Cozier

Studies have indicated that globally, the risk of developing covid-19 increases with greater use of public transport.

Editorial image credit: William Perugini / Shutterstock

Researchers at the University of Birmingham have developed an antimicrobial coating for air filters which is said to kill bacteria, fungi and viruses, including SARS-CoV-2. The development, which provides a potential solution for preventing the spread of airborne infections on trains, was carried out in partnership with the companies NitroPep Ltd, Pullman AC and the University of Nottingham.

Publishing the work in the journal Scientific Reports, air filters were coated with chlorhexidine digluconate (CHDG), a chemical biocide. In the laboratory, cells of the Wuhan strain of SARS-CoV-2 were added to the surface of the treated filter and a control filter, and measured over an hour. The team said the results indicated that while much of the virus remained on the surface of the control filter, all of the SARs-CoV-2 cells were killed within 60 seconds on the treated filter. The team added that similar results were seen in experiments were bacteria and fungi.

The treated filters were tested in heating, ventilation and air conditioning systems in train carriages. The trials found that no pathogens survived on the treated filter, even after three months on-board the train. The researchers noted studies had indicated that globally, the risk of developing covid-19 increases with greater use of public transport. Other studies showed higher rates of flu-like illnesses in people travelling on the UK’s London underground, as well a six-fold increase in respiratory infection in people using a tram or bus.

Dr Felicity de Cogan, Royal Academy of Engineering Industry Fellow at the University of Birmingham said; ‘The covid-19 pandemic has brought to the forefront of public consciousness the real need for new ways to control the spread of airborne respiratory pathogens…Most ventilation systems recycle air, and the filters currently being used in these systems are not normally designed to prevent the spread of pathogens, only to block air particles. This means filters can actually act as a potential reservoir for harmful pathogens.’

Dr de Cogan added that while there exist a number of novel filters for ‘purifying air’ these have fallen short as they either lack energy efficiency or speed in effectiveness and are not ideal for the majority of existing heating, ventilation and air conditioning systems which would require significant infracstructure upgrades to use them.


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