Just when we started to breathe a sight of relief after a long COVID winter, we are facing more contagious COVID mutations and infection rates are going up again. And now governments are telling us to wear better masks. Like those FFP2 masks they told us not to wear before ?
Confused ? lets clear up a few things:
Masks filtration and leak ratio
Masks protect us by filtering most of small particles. For example a surgical mask is CE qualified if it can filter 85% or more of particles with size of 3 microns. FFP2 filtration level masks must filter more than 94% of particles with size 0.3 microns.
Since COVID particle size is small and closer to 0.3um, FFP2 masks are much more suitable than surgical masks to protect against COVID viral loads. That is why they are recommended to all front line workers.
In addition, a mask is defined by its total leak rate, that is the amount of small particles that make it to your lungs, from passing through the filter or through leaks due to fitting. So a surgical masks may let only 15% of small particles in, but you must add the leaks due to poor fit of the ear loops or the nose clip. Then you probably reach a total filtration leak rate of 30% or more for very small particles. According to the recently published advice from the US Center for Disease Control, a properly fitted surgical mask only catches 63% of small droplets exhaled by someone who cough. For a poorly fitted surgical mask or a cloth mask, the total filtration barely reaches 40%.
By comparison FFP2 level protection provides a filtration leak for very small particles which is less than 6% (and on average our FFP2 level masks provide actual filtration leak of only 2%) and a total leak rate of less than 8%. FFP2 masks achieve this lower combined leak rates with multiple filtration layers and tighter headbands or with ear loops which can be tightened to provide a good fit. So with a properly adjusted FFP2 mask, you will probably experience combined leak rate of about 5% or less. That is multiple times better than your average surgical mask or cloth mask.
Viral load and contagion
All that did not matter until we found ourselves in a winter where contagion rise since we spend more time indoors and we now have virus mutations which are much more contagious. Virus contagion is mostly dependent on the viral load required to contaminate an exposed subject. The longer and the closer you are with a virus carrier, the higher the risk of contagion. While we could get away with loose masks and 1 meter social distancing with COVID version 1, we now need to increase our level of protection to protect from the more contagious versions of COVID virus which spread faster, with lower viral loads.
Most contagions occur indoor, with prolonged exposure and with people eating or drinking and talking without masks or wearing their mask improperly. Or in poorly ventilated places with many people together for more than a few minutes. Think restaurants, bars, coffee shops, public transport, airports and train stations, subways, crowded supermarkets and indoor lines.
So with more contagious COVID virus, you need to consider wearing a good quality mask with proper fit in all these higher risk situations. The government in France, Germany and across Europe now recommend that you wear masks with higher protection level.
Protect yourself when it matters
So when you are in these high risk situations indoor or in places where social distancing cannot be maintained, you should wear a mask with FFP2 protection level that is fitted properly to your face. With strong bands behind your head or ear loops that can be tightened properly to your face.
And when you can maintain social distancing, with good ventilation and outdoor, you can probably wear just about any mask. In fact when outdoor with social distancing and good ventilation, masks do not serve much purpose. But that is another story.
You should also purchase your mask from a supplier you trust. Overseas suppliers have proliferated and even with a CE certification, they do not always maintain the promised protection level (see here). There are also many fake 3M respirators being sold online. Purchasing from a European manufacturer may reduce these risks.
You need to wear a well fitted FFP2 mask in all high risk situations. And you can wear a surgical mask or a reusable cloth mask when risks are lower if you prefer. FFP2 protection masks can be quite comfortable so you may also want to use such masks all the time if you can. This is what the German government now requires.
Wear two masks?
A quick note: some articles have been recommending wearing two masks. According to the same CDC recommendations, combining a surgical mask and a cloth mask provides high protection which is close to the protection you get from a single FFP2/N95 respirator. Certainly much better than a single poorly fitted surgical or cloth mask.