As public health officials around the world work to contain the outbreak of coronavirus, many are choosing to protect themselves with disposable face masks, but how effective are they at blocking the spread of viruses?
Controlled studies on the effectiveness of masks are difficult to carry out, and health agency guidelines are often confusing and contradictory. The US Centers for Disease Control and Prevention do not recommend masks for use by people without symptoms, whereas the Occupational Safety and Health Administration (OSHA) encourage voluntary use as a physical barrier against hazards.
However, a study from the University of Michigan found that wearing disposable masks and using alcohol-based hand sanitizers could prevent the spread of influenza virus by as much as 50 per cent.
The yet-unnamed coronavirus, a family of viruses that affect the respiratory tract, has killed over 100 people and sickened over 4000 at last count. The virus is believed to have started in a livestock market in Wuhan, China and spread from animals to humans, with cases now confirmed in 13 other countries.
According to Columbia’s Mailman School’s professor of epidemiology Stephen Morse, the best evidence suggests that face masks catch bacteria shed in liquid droplets, splashes or sprays, including virus-containing droplets, but are less effective in filtering out fine viral particles in the air.
“Wearing a surgical mask to prevent infection is popular in many countries, most notably in China, where memories of SARS have helped fuel anxiety over the new coronavirus.”
“But there isn’t a lot of high-quality scientific research to gauge the effectiveness of masks and the results are mixed. Some studies suggest they may provide some benefit, but what’s out there isn’t conclusive.”
Morse does not see any harm in wearing masks, but if people do decide to do so, they should heed the following advice:
- Wear the mask consistently, at least whenever there is any risk of infection. People often find them uncomfortable and take them on and off, rendering them ineffective. Wash your hands after removing the mask.
- Put the mask on correctly, with a good fit covering your nose and mouth. A loose fit between the mask and face will not provide protection from germs or contaminants.
- Do not let the mask give you a false sense of security. Wearing a mask does not mean you should avoid tried and true hygiene practices. Wash your hands regularly, keep away from people who are coughing and sneezing, cover your coughs and sneezes (and wash your hands afterwards), don’t touch your mouth, nose or eyes after touching a potentially contaminated object.
- If you experience symptoms, such as cough, headache, fever, sore throat or a general unwell feeling, remain at home.
The US Food and Drug Administration has also cleared certain filtering (face mask) respirators, known as N95s, for use by the public. They are considered to provide greater protection but are more difficult to wear and require a tighter fit on the face.