Construction sites around the world are filled with dust, heavy metals and dangerous gases. For decades, construction workers have relied on masks made by companies like 3M to dramatically reduce their exposure to polluted air, as the masks are at least 95 percent efficient at filtering inhaled air, test results from independent labs prove.
This is exactly the meaning of "95" in the "N95 mask" we often see. (N95 type mask is one of the 9 anti-particulate masks certified by the National Institute of Occupational Safety and Health. Under the testing conditions specified in its standard, the filtration efficiency reaches 95%. N95 is not a specific product name. As long as it meets N95 Standards, and products that pass the review can be called "N95 masks".)
In the test of N95 type masks, one person wears the mask for about 15 minutes. The wearer of the mask should move in many positions. The mask is connected to a special machine to record the particle concentration inside and outside the mask. If the reduction of particles in the air inside the mask exceeds 95%, then the mask passes the N95 test. Many masks have received this certificate, and in light of this, it can be determined that these masks can greatly reduce our exposure to the dangerous PM0.3-PM2.5 particles in air pollution.
