The most effective DIY facemask involves a combination of different fabrics, or a bit of quilt that already has a set of layers, a new study suggests.

The US research was prompted by the on-going shortage of high quality masks for people to use during the coronavirus pandemic.

Before the study, there was little hard scientific data on the effectiveness of fabrics used in cloth masks to prevent the transmission of aerosol particles, which range in size from 10 nanometers (nm) to 10 microns (10,000 nm).

After testing various fabrics’ ability to block tiny particles, the US researchers concluded that a homemade mask made from a cotton layer, combined with a layer of chiffon and/or batting material, could fend off virus particles best.