Researchers reporting in ACS Nano have developed an N95 mask membrane that can be attached to a mask and removed when needed, which could help reduce the spread of Covid-19.

The filter has a smaller pore size than normal N95 masks, potentially blocking more virus particles.

Traditional N95 masks filter about 85% of particles smaller than 300 nanometres (nm). With the SARS-CoV-2 virus that causes Covid-19 sitting in the size range of 65nm to 125nm, some virus particles could slip through.

The new membrane features pores smaller than 60nm, placed at a maximum of 330nm from each other to achieve good breathability. The membrane is also self-cleaning because droplets slide off it, preventing the pores from getting clogged with viruses and other particles.