Invisible masks are similar to nasal congestion. Both ends of the connecting cord are equipped with slots for inserting disposable filters. Both ends can be inserted into the nostril, this invisible mask cannot cover the mouth. It is more like two small stuffy noses. It can be inserted into the nostril when wearing it, and then the nano electrostatic filter cotton can automatically isolate the dust without affecting normal breathing.
This so-called invisible mask is a breathable nasal congestion with filtering function. In fact, it contains a kind of activated carbon, which can isolate some larger dust particles to a certain extent and absorb some toxic gases. The first type of invisible mask may be useful for some large particles, that is, it can block ashes and pollen, but it is certain that such a simple invisible mask is useless for PM2.5.