How do I know if my mask actually works? What about the 'candle test'?
A few simple pointers can help you spot a quality mask from a dud.
Published on the 13 Aug 2020 by C Raina MacIntyre
Masks now come in all shapes and sizes, but some are better at protecting against coronavirus than others. Image from Shutterstock
With mask wearing in public compulsory in Victoria and recommended in New South Wales, many Australians are buying, wearing or making face masks for the first time.
of counterfeit or potentially substandard masks on the market may lead some people to question whether their surgical or cloth mask actually works.
So what can you look out for when buying a mask to make sure it does what it鈥檚 supposed to do?
And how can you test one you鈥檝e bought or made?
What do I look for in a surgical mask?
Surgical masks (also known as medical masks) are usually made of three or four layers, most commonly polypropylene.
Ideally, they should meet for how well they filter and how resistant they are to water.
Only masks the Therapeutic Goods Administration (TGA) approves as medical products (officially known as medical devices) can be used in hospitals.
If a mask meets Australian standards as a medical device, a label on the packaging, plus a code indicating the standards it has met, such as:
-
AS/NZS 4381:2015
-
ASTM F2101-14 or EN 14683:2014
-
ISO 22609 or ASTM F1862/F1862M-13.
If your surgical mask says 鈥渘ot for medical use鈥, it doesn鈥檛 necessarily mean it鈥檚 useless. It just means it has not been submitted to the TGA for approval as a medical device.
If that鈥檚 the case, you can assess it using one of the methods below.
What do I look for in a cloth mask?
Cloth masks are non-medical devices. But they can be to be reasonably protective.
If you鈥檙e buying one online or making one yourself, check it has. A single-layered mask is better than no covering, but are better than one, and three layers are better than two. are better still.
Look for a fine weave, high thread count and dense material. Flimsy or see-through material, or material with large gaps, is not adequate because droplets and aerosols can pass through the gaps.
For a cloth mask, pure cotton is not a good choice for the outer layer, as it is absorbent. If someone else is coughing and sneezing near you, you want your mask to block those droplets rather than enable them to pass through the mask and infect you. A polyester or cotton-polyester blend is a better choice for this outer layer.
So for cloth masks, at least three layers, including a water-resistant outer layer. The inner layer can be cotton, as that makes it more comfortable to wear, because it will absorb moisture from your breathing.
Check also that your mask fits well around your face. If you have gaps around the edges of your mask, you can breathe in unfiltered, contaminated air.
Look to see if there鈥檚 a nose bridge piece or other adjustable edge to help mould the mask around your nose and the top of your cheeks. If your mask is loose-fitting, a over the top can improve the fit and seal.
And remember to wash your cloth mask daily.
How can I test my mask at home?
Test for good filtration and fit
For filtration and fit, you can do some rather at home.
But a much simpler method is the candle test, popularised by US science educator . If you can blow out a candle while wearing your mask, that鈥檚 a fail.
It means your mask doesn鈥檛 adequately stop the flow of air. If you can blow air out, air can also leak inward just as easily.
Put on your mask, light a candle, then try to blow out the flame.Test for water resistance
The virus is carried on water droplets expelled when infected people talk, cough and sneeze. If these droplets land on your mask, you want the outer layer to repel them.
A TGA-approved mask will be water resistant. But other masks are. So you can test a non-approved surgical mask or cloth mask at home.
If a drop of water on the outside surface is absorbed straight away, . If the drop forms a bead, the mask is water-resistant.
Whether you go for a surgical mask that鈥檚 an approved medical device, an unapproved surgical mask, or a cloth mask, these simple tips should help you assess it before leaving the house.
Masks are a simple method for helping of the virus that causes COVID-19, alongside physical distancing, hand-washing and other infection control measures. If enough people wear them, they may even help .
, Professor of Global Biosecurity, NHMRC Principal Research Fellow, Head, Biosecurity Program, Kirby Institute,
This article is republished from under a Creative Commons license. Read the .
听