A mask is a kind of protective equipment worn on the mouth and nose to filter the air entering the mouth and nose to prevent harmful gas, dust, droplets from entering and leaving the wearer's mouth and nose. It is made of gauze or paper. Masks have a certain filtering effect on the air entering the lungs. Wearing masks has a very good effect when respiratory infectious diseases are prevalent or working in dust and other polluted environments. So how do we choose a mask suitable for our job? Today we will talk about the protective effects of various masks.
Some masks are equipped with mask nose wire. The surface of the mask has large pores and cannot withstand particles with a particle size of only 2.5 microns. Some cotton masks with a filtering effect of more than 90% have very large airflow resistance. People will have difficulty breathing after wearing them. The basic function is to prevent cold and keep warm.
Ordinary gauze mask:
Usually there is no nose wire. The most common gauze mask blocking principle is a mechanical blocking effect. Through a layer of mechanical blocking, large particles can be blocked, but particles with a diameter of less than 5 microns cannot be blocked, let alone Said PM2.5 particulate matter. Its function is to block particles above 5 microns in diameter.
Activated carbon mask:
Activated carbon masks can reduce some peculiar smells, but the protection efficiency of particulate matter is not significantly enhanced. Activated carbon itself is a kind of particles, but it is a hazard for patients with chronic respiratory diseases or the infirm. Therefore, activated carbon masks do not increase the protection efficiency.
Ordinary medical masks:
Medical surgical masks and medical disposable masks can block particles larger than 4 microns in diameter. According to general medical standards, for 0.3 micron particles, the transmittance rate of medical surgical masks is 18.3%, and the transmittance rate of ordinary disposable medical masks is 85.6%. For example, medical masks are only suitable for rice particles with a diameter of 4 microns.
Medical KN95 masks can block most 2.5-micron particles. The permeability of such particles detected in the laboratory is only 0.425%. It can be said that more than 99% of the particles are blocked, so KN95 masks have the highest protective effect. of.