When paper towels are soaked in a saline solution and then allowed to dry, they can effectively filter out particles comparable in size to the SARS-CoV-2 virus, a US study suggests.

The ability of kitchen paper towels, laboratory paper towels and surgical mask filters to block tiny particles was dramatically improved by salt soaking, researchers report in the American Journal of Infection Control.

The researchers say the salt treatment is both as a way of improving DIY cloth masks and also extending the life of surgical masks.

An earlier study had shown that salt treatment of surgical masks improved their ability to block various strains of the flu virus, according to lead author Jonathan Carnino, a research assistant in the department of pulmonology at the Boston University School of Medicine, Massachusetts.