Can ordinary masks really protect against PM2.5?

There is very serious smog in Beijing now, so many friends wear masks when they go out. Masks are in short supply now, and many businesses selling masks say that their masks can protect against PM2.5. Although the prices of masks have been rising, it still cannot stop people from buying masks to block the haze. So, can ordinary masks protect against PM2.5?

Most masks cannot block PM2.5. "This is just a beautiful lie. Most of the 'PM2.5 masks' sold on the market are more hype than effectiveness." The size of PM2.5 is equivalent to one twentieth of the tip of a needle, and ordinary non-woven mask fibers cannot block it at all.

The results of the airtightness test on several masks showed that: ordinary gauze masks have no barrier to PM5 and below. Ordinary gauze masks are fiber masks. Their flow-blocking principle is a mechanical blocking effect. Through layers of mechanical blocking, large particles can be blocked, but particles with a diameter of less than 5 microns cannot be blocked, not to mention PM2.5 particles. Ordinary medical masks: very effective against PM4. Medical surgical masks and medical disposable masks can block particles with a diameter larger than 4 microns. The test results show that according to general medical standards, for particles of 0.3 microns, the transmittance of medical surgical masks is 18.3%, and that of ordinary disposable medical masks is 85.6%, which indicates that these two types of medical masks have limited blocking effects on fine particles. And N95 masks: most PM2.5 are blocked. When using a medical N95 mask to detect particles of 0.3 microns, larger particles can be blocked. However, when tested in a mask airtightness laboratory, the transmittance of the medical N95 mask is only 0.425%, which means that more than 99% of the particles are blocked.

Although tests show that the higher the filtration efficiency, the better the effect. However, the test was a sealing experiment conducted in a hospital environment, and the city has a large amount of emissions from automobile exhaust and other gases, and many particles in the air are oily, which will also reduce the actual protective effect of the mask.

Most PM2.5 masks have an antibacterial fabric on the outside, a warm filling in the middle, and a PM2.5 filter underneath, which is far from being truly high-tech.

The above is an introduction on whether ordinary masks can prevent PM2.5. In fact, ordinary masks cannot block PM2.5. However, we don’t need to be too nervous when facing smog. In fact, wearing masks in normal times is a very correct choice. Although ordinary masks cannot prevent PM2.5, they can also prevent some large particles in the air.