Hi all. I've found a very interesting paper from 2017 that documents a very low-cost and easy intervention for increasing the efficacy of fabric or surgical masks for catching and de-activating viral aerosols. I'll summarize it briefly and hopefully Dr Bromage & others with more domain expertise can review & comment, because if it does what it says on the label this should be much more widely known. The citation is:
Quan, F., Rubino, I., Lee, S.et al.Universal and reusable virus deactivation system for respiratory protection.Sci Rep7,39956 (2017). https://doi.org/10.1038/srep39956 This group found that if you take a regular surgical mask and soak it in a 30% NaCl solution, then let it dry completely, a crystalized salt coat forms on the fibers of the mask. This makes them hydrophilic: they catch virus-bearing aerosol droplets much more readily, and the water from the droplets temporarily dissolves some of the salt. As the water then evaporates again, the salt recrystalizes -- trapping the virus in the salt, where the sheer osmotic pressure then deforms and tears the membrane envelope of the virus apart, deactivating it in ~3 minutes. Very cool.
Using reclaimed H1N1 from the treated & untreated masks, they infected rodents and showed that those who got the virus from the untreated masks had the same death rate as the control group (100% by day 10), whereas the salted mask group had a 0% fatality rate. *Very* cool.
They used a couple of different strains of influenza in the experiments, but theoretically this should work the same for coronaviruses, no? One small detail: they actually used a 29% NaCl and 1% polysorbate surfactant solution, but the surfactant is only there to ensure even distribution of the salt adhering to the mask, and I don't think it's necessary. In a pinch, a drop of household detergent should have much the same effect, no?
Anyway, I would very much appreciate it if Dr Bromage or anyone else with some relevant expertise could weigh in on this; I have undergrad level chemisty, biology, and stats and know how to read research papers, but I'm not a professional. If this works as advertised, I think everyone should know about it. Cheers.