The Ffp2 mask, as well as the surgical one, could be used without risk up to 40 hours, if stored correctly. Tip number one is to keep it away from moisture. Surgery under the Ffp2 is absolutely to be avoided (the opposite is right), just as the habit of using plastic bags or cases to store them in a bag or pocket is wrong. With a warning: if you are not exactly meticulous or if you are dealing with the little ones, the ideal choice remains to change them every day. To suggest the most ‘hygienic’ way to use these accessories, which we cannot do without now, is Cristiana Boi, a chemical engineer at the University of Bologna, who with her team took care of the tests. for the surgical masks and also worked on the Ffp2. “On surgical masks – he explains to Adnkronos Salute – but the discussion can also be extended to Ffp2, we have seen that they work well up to 40 hours, a number designed for a 5-day work week for 8 hours. It does not necessarily have to be treated. 40 hours in a row, however: if you use an hour a day to do the shopping, you can keep it up to 15 days, as long as you keep it well. These devices fear humidity. So they should not be stored in a plastic bag and leave the paper or the fabric there, but the ideal would be to hang them in the house in a clean place “. The Ffp2 “protects more not for the material – specifies the expert – but for its greater adherence to the face. This is why putting it over the surgical is absolutely wrong. The opposite is better, which allows an extra layer of filtration and protects from dirt the FFP2. It’s what the Americans call the ‘Emmental effect’, referring to the holes in the famous cheese: if I put more layers together, the holes in different positions create more ‘fullness’ and retain more particles “. Even kids who go to school can “keep it for a week, if you are sure they keep it clean,” Boi points out. Outdoors, then, “it is not necessary to use the Ffp2. The suggestion is to bring the two types with you, using the surgical outside, which allows you to breathe more easily, and the Ffp2 when you enter an enclosed place”.