What’s the Evidence on Face Masks? What You Heard Was Probably Wrong

While some time ago anyone wearing a custom face mask in public areas might have drawn stares in several countries unused to this particular behaviour, they are now a reminder with the strange times we are in. And as governments around the world begin to ease their lockdowns to allow for their citizens in the market to mingle within the wider world again, growing variety of everyone is opting to use face masks in public.

Researchers at Cambridge University tested the strength of an array of household materials for use in homemade masks. They measured how well the family unit materials could capture and filter small particles.

Leaving the medical-grade masks to health workers, where they may be needed most, folks are increasingly looking to make their unique masks in your house. WIRED has picked three simple designs using fabrics you currently have around the house and without the need for master-level sewing skills.

The Case for Masks

For the reasons like the coronavirus outbreak, there are three main kinds of masks: respirators, surgical masks, and fabric, or homemade, masks.

Coffee filters. One of the masks designs the CDC has published carries a layer of a coffee filter. They are easily available and disposable.

The problem is that washing or sanitizing a medical mask will degrade it, making it less efficient. Scientists are finding that using UV light, heat and humidity or possibly a bleach vapor could work, nevertheless the methods are developed for used in hospitals with special equipment and are not for home use. You can learn more within our story about efforts to decontaminate a large number of medical masks.


The other study, published April 3 inside journal Nature Medicine, used a more elaborate method of collecting the herpes virus particles that sick people emit. The researchers asked 426 volunteers to breathe for 30 minutes in a cone-like device that captures everything exhaled. Of these, 43 patients had influenza, 54 patients had rhinoviruses and 17 patients had seasonal coronaviruses (the kinds that create colds, not the sort that creates COVID-19). This method allowed the study to quantify how much virus was found in droplet particles, that are in excess of 0.0002 inches (5 microns) in diameter, versus aerosol particles, which can be 5 microns or smaller. The participants were randomized to either wear a surgical mask or otherwise not wear a mask through the study.