A mask worn for too long can increase the risk of contracting the virus.
- The mask that is supposed to protect against contamination; can have the opposite effect if worn too long or if it is too dirty
- The reduction in the speed of air entering the nose caused by the mask facilitates the inhalation of aerosols potentially carrying the virus
Wearing a mask is one of the tools in the fight against the new coronavirus. It is more about avoiding contaminating those around us, than a way of protecting ourselves. But when we wear a mask for too long or fail, we increase our risk of contracting the virus. In Physics of Fluidsscientists have made the observation thanks to the modeling of the inhalation of air and the deposit of droplets on the face when wearing a mask.
Better to wear nothing rather than a worn mask
The researchers point out that wearing a mask changes the way we inhale air: it enters the nose and mouth via the surface of the mask, at a slower rate, compared to when we breathe without a mask. This reduced speed favors the inhalation of aerosols, which means that even if the mask eliminates particles, the remaining ones can more easily pass into the respiratory tract.
According to the researchers’ analyses, carried out through modeling, a new mask has a filtration capacity of 65%, compared to 25% when it has already been used. “It is natural to think that wearing a mask, whether new or old, is always better than wearing nothing, says lead study author Jinxiang Xi. Our results show that this belief is only true for particles larger than 5 micrometers, but not for those smaller than 2.5 micrometers.He even claims that wearing a mask with less than 30% filtration capacity is worse than wearing nothing at all.
The mask is not enough to protect yourself and others
For mask-wearing to be effective, WHO provides some practical advice : wash your hands before putting it on, taking it off and after, but also covering your nose, mouth and chin well, placing your fabric mask in a clean plastic bag, washing it all days or to throw it away after use if it is a surgical mask. Do not wear a dirty or wet mask and especially do not lend it. In any case, the World Health Organization recalls that a “mask does not provide sufficient protection against COVID-19 on its own“. It does not exempt us from respecting barrier gestures and social distancing.
.
