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What are facemasks and do we need to wear them?

Colin Dang

What types of face masks work best?

There’s been a lot in the news recently about the pros and cons of wearing a face mask in public to protect you - or others - from contracting coronavirus. In our latest blog we take a look at what face masks work the best for when you make trips out into crowded spaces.


Fit-and seal-tested respirators are made of tangled fibres that are highly effective at filtering pathogens in the air. These respirators must meet the rigorous filtration standards set by the National Institute for Occupational Safety and Health (NIOSH).

The diameter of the coronavirus is estimated to be 125 nanometers (nm). Keeping this in mind, it’s helpful to know that:

  • Certified N95 respirators can filter 95 percent of particles that are 100 to 300 nm in size.
  • N99 respirators have the ability to filter 99 percent of these particles.
  • N100 respirators can filter 99.7 percent of these particles.

If you’ve ever wondered how you can breathe in a mask, some of these respirators have valves that allow exhaled air to get out. However, the downside of this is that other people are susceptible to the particles and pathogens that are exhaled through these valves.

Frontline healthcare and other workers who need to use these masks as part of their job are tested at least once a year to verify proper respirator size and fit. This also includes checking for air leakage using specific test particles. These routine tests help ensure that harmful particles and pathogens can’t leak through thus keeping everyone safe.

Surgical masks

Typically, surgical masks are disposable, single-use and are cut into a rectangle shape with pleats that expand to cover your nose, mouth, and jawline. They are composed of breathable synthetic fabric.

Unlike respirators, surgical face masks don’t have to meet NIOSH filtration standards. They aren’t required to form an airtight seal against the area of your face that they cover. How well surgical masks filter pathogens varies widely, reports show.

Despite differences in fit and filtration capacity, a randomized trial found that surgical face masks and N95 respirators reduced participant risk of various respiratory illnesses in similar ways.

Proper and consistent use of the mask played a more important role than the type of medical-grade mask or respirator worn by the participants in the study.

Cloth masks

Do-it-yourself (DIY) cloth masks are less effective at protecting the wearer because most have gaps near the nose, cheeks, and jaw where tiny droplets can be inhaled leaving you more exposed to the virus. Also, the fabric is often porous and can’t keep out tiny droplets.

Although cloth masks tend to be less effective than their medical-grade counterparts, experimental results suggest they are far better than no mask at all when worn and constructed properly.


Presently a visit to the supermarket can resemble a Dick Turpin convention, but what does the evidence say about how well face masks work and who should wear them?


The main reason for someone to wear a mask is to prevent other people from being infected from Covid-19. It is vital for healthcare workers to wear face masks both during surgery and other routine procedures to prevent patients being infected and to stop the virus spreading. The masks that health workers wear are of the highest medical-grade.


The main reason masks work more effectively in hospitals is partly because they are changed often and correctly fitted. Health workers are also trained to know how to remove masks without becoming infected.


Presently, there is a lack of good evidence of the effectiveness of standard face masks worn by the public. There aren’t any randomised controlled trials that have been carried our previously on face masks for example to test how face masks can prevent the spread of influenza, which is the model for respiratory virus diseases.


There are many scientific studies being rapidly carried out across the world to try and determine how best to stop the spread of the virus and scientists are also working to gather more evidence about whether people who have the virus but are yet to develop symptoms can actually transmit the disease to other people before they develop them.


Without any conclusive evidence, it may not be wise to rely on something that might give you a false sense of security. Indeed, removing a mask that has been contaminated may increase your risk of infection. Also, with medical staff and patients in hospital in dire need of masks, encouraging the mass consumption of mask wearing could reduce the supply for the people who need them the most.


Stay tuned for more news on this as the World Health Organisation decides in the near future about whether the public should be wearing face masks to protect against coronavirus. In the meantime, there are plenty of things we can do to keep ourselves safe and healthy, through hand hygiene, social distancing and using the oldest trick of all - common sense!


If you have any questions or concerns about coronavirus, please contact your GP.


The Coda Team

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