As everyone knows, KN95‑rated masks can help protect against the COVID‑19 virus. But how do you choose the right mask? Today, we’ll walk you through some key information about KN95‑rated masks.
I. What is a KN95 mask?
KN95 masks are Chinese‑certified respirators that achieve a filtration efficiency of at least 95% against non‑oil‑based particulates. In China, KN95 masks adhere to the KN standard, which was developed based on the U.S. NIOSH standards for dust‑protective respirators. Common protection levels are rated at 90%, 95%, and 100%, with 90% indicating an efficiency of at least 90% against non‑oil‑based particles, while 95% and 100% denote filtration efficiencies of at least 95% and 100%, respectively.
II. What is the purpose of KN95‑grade masks?
KN95‑grade masks provide a certain level of protection against various airborne particulates, non‑oil‑based particles, and viruses. For the current novel coronavirus, KN95‑grade masks offer the best protective performance; when worn correctly, they can help prevent infection.
3. How often should KN95‑grade masks be replaced?
Under normal circumstances, when used outdoors—in public places such as subways, buses, supermarkets, and shopping malls—KN95‑level masks should be replaced every 4 to 6 hours. However, in areas affected by the novel coronavirus outbreak, it is recommended to replace KN95‑level masks every 2 hours.
At present, international organizations, including the WHO, have not reached a definitive conclusion on the optimal duration of N95 mask use, and China has yet to establish specific regulations regarding mask‑use durations. Some researchers have investigated the protective efficacy and wear time of KN95 medical protective masks; their findings indicate that after two days of wear, the filtration efficiency remains above 95%, with only minor changes in breathing resistance, whereas after three days, the filtration efficiency declines to 94.7%. The U.S. CDC recommends that, in situations where mask supplies are limited, masks may be reused as long as they are not visibly soiled or damaged—such as by creases or tears.
Properly certified KN95‑grade protective masks have a shelf life because prolonged storage can cause them to lose their electrostatic charge, rendering them ineffective. While KN95 masks can indeed be reused, they must be handled using specialized knowledge—never attempt to do so on your own.
