Are non-medical three-layer disposable masks useful?

It has a certain effect, but it is not as protective as medical masks.
The non-medical three-layer masks currently on the market have a non-woven outer layer, which can block droplets and dust, the middle layer is a melt-blown cloth, which can filter fine particles, and the inner layer is a non-woven fabric, which can absorb the exhaled heat.
It is comfortable on the skin, and it can block droplets and inhalable particles to a certain extent, but it has no protective effect on smaller viruses.
If it is used in a medical environment or to prevent virus infection, it is recommended to wear ordinary medical masks, medical surgical masks, medical protective masks, etc. These types of masks have a clear preventive effect on virus infection. Layer Disposable Face Mask