1. Researchers have developed a more efficient membrane filter that can be attached to a regular N95 mask and replaced when needed. 2. This filter has a smaller pore size than normal N95 masks, potentially blocking more virus particles. 3. N95 masks filter about 85 per cent of particles smaller than 300 nm. The researchers noted that SARS-CoV-2, the coronavirus that causes COVID-19 is in the size range of 65-125 nanometers (nm), so some virus particles could slip through these coverings. 4. To overcome these problems, Muhammad Mustafa Hussain and colleagues wanted to develop a membrane which more efficiently filters particles the size of SARS-CoV-2 and could be replaced on an N95 mask after every use. 5. The hydrophobic membrane also cleans itself because droplets slide off it, preventing the pores from getting clogged with viruses and other particles.