The 'candle test', an unrigorous experiment to find out if a mask is valid
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Videos on YouTube in which people (even health professionals) appear doing the famous 'candle test' have been going viral for weeks. The experiment is simple: with the mask on, a subject tries to extinguish the flame of a lighter to test whether it is valid or not. The theory is that if the flame does not go out, the mask is 'good' and if it goes out, the mask is 'bad'. It is such a simple and visual experiment... as it is not very rigorous.
Why is the "candlestick test" not a valid experiment?
First of all, because the masks have been designed to filter particles (such as microorganisms) and not gases (such as oxygen). To put ourselves in a situation, the size of viruses ranges between 10 and 100 nanometers, while the size of oxygen is less than one nanometer. That is to say: the particles are significantly larger than the gases and, therefore, it is not only possible (but to some extent desirable) for a mask to let air through but not the particles .
Second, it is not a standardized experiment with constant parameters, but rather a home test that can vary depending on the intensity with which the individual blows . As in the story of the three little pigs, the wolf does not blow with the same intensity when trying to knock down the straw house than the brick house.
Thirdly, because if accurately measuring the validity of the mask were something so simple that anyone could do it at home, we would not need accredited entities to certify that the masks do or do not comply with the regulations. And yet they are necessary.
