The Effectiveness and Proper Use of KN95 Masks

In recent years, particularly during global health events, filtering facepiece respirators like the KN95 mask have become a familiar tool for personal protection. While often compared to N95 masks, it’s important to understand what a KN95 is, how it works, and how to use it correctly to ensure maximum effectiveness. This guide provides a detailed look at KN95 masks to help you make informed decisions about your safety.

What is a KN95 Mask? Understanding the Standard

A KN95 mask is a type of filtering facepiece respirator that is manufactured and tested according to the Chinese standard GB2626-2019. The “95” in its name signifies its filtration efficiency: a properly fitted KN95 is designed to filter at least 95% of non-oily airborne particles down to 0.3 microns in size.

These masks are often compared to other international standards:

• N95 (United States): Certified by the National Institute for Occupational Safety and Health (NIOSH) under standard 42 CFR Part 84.
• FFP2 (Europe): Certified under standard EN 149:2001.
• KF94 (South Korea): Certified under standard KMOEL – 2017-64.

While all these masks are rated to filter approximately 95% of airborne particles, they are certified by different regulatory bodies in their respective countries and have minor differences in testing requirements such as pressure drop and flow rate.

The Anatomy of a KN95 Mask: How It Works

The effectiveness of a KN95 mask comes from its multi-layer construction and its ability to form a tight seal around the face. A typical KN95 mask consists of:

1. Outer Layer: A non-woven, fluid-resistant fabric that acts as the first barrier against splashes and large droplets.
2. Filter Layers: This is the core of the mask, usually composed of one or more layers of melt-blown polypropylene fabric. This material is not just a physical sieve; it carries an electrostatic charge that actively attracts and traps tiny aerosol particles.
3. Structural Layer: A layer of hot air cotton or similar material that provides shape and support to the mask.
4. Inner Layer: A soft, moisture-absorbing non-woven fabric that rests against your skin, enhancing comfort and wicking away moisture from your breath.

The design is completed with elastic ear loops and, crucially, an adjustable metal or plastic nose clip. This clip is essential for molding the mask to the bridge of your nose to prevent air from leaking in or out from the top.

Proper Use for Maximum Effectiveness: A Step-by-Step Guide

A high-quality KN95 mask is only effective if it is worn correctly. A poor seal can render even the best mask ineffective. Follow these steps for proper use:

1. Hand Hygiene: Before touching a clean mask, wash your hands thoroughly with soap and water for at least 20 seconds or use an alcohol-based hand sanitizer with at least 60% alcohol.
2. Inspect the Mask: Check the mask for any obvious tears, holes, or damage. Ensure the ear loops and nose clip are intact.
3. Donning (Putting on the Mask):
   • Hold the mask in your palm with the nose clip at your fingertips, allowing the ear loops to hang freely.
   • Place the mask over your face, covering your nose and mouth completely.
   • Pull the ear loops over each ear.
   • Using both hands, mold the nose clip firmly to the shape of your nose bridge to create a tight seal.
   • Adjust the mask to ensure your chin is covered and there are no gaps on the sides.
4. Perform a Seal Check: Place both hands over the front of the mask and breathe sharply.
   • If you breathe in (negative pressure): The mask should slightly collapse inward.
   • If you breathe out (positive pressure): You should not feel any air leaking from the edges of the mask, especially around your nose or cheeks. If you feel a leak, readjust the nose clip and the position of the mask until the seal is secure.
5. Doffing (Taking off the Mask):
   • Avoid touching the front of the mask, as it is considered contaminated.
   • Lean forward slightly and remove the mask by handling only the ear loops.
   • Pull the mask away from your face.
6. Disposal and Hand Hygiene:
   • Dispose of the used mask immediately in a closed-lid trash can.
   • Wash your hands thoroughly again.

Important Considerations: Certification, Counterfeits, and Reuse

• Certification: It is critical to understand that NIOSH does not certify KN95 masks; NIOSH certifies N95s. Authentic KN95 masks should be marked with the GB2626-2019 standard. During periods of N95 scarcity, the U.S. CDC did provide guidance and lists of tested KN95s that met certain performance criteria, but this is not the same as formal NIOSH approval. Always look for the standard printed on the mask itself.
• Avoiding Counterfeits: Due to their popularity, counterfeit KN95 masks are common. To avoid them, purchase masks from reputable suppliers and be wary of products with no markings, missing manufacturer information, or claims of “NIOSH approval” for a KN95.
• Reuse: KN95 masks are designed and intended for single use. With each use, the ear loops can stretch, the fit can degrade, and the mask can become soiled. Furthermore, moisture from your breath can gradually reduce the electrostatic charge of the filter layer, lowering its filtration efficiency. For these reasons, the mask should be disposed of after a single use, or when it becomes dirty, damaged, or difficult to breathe through.

Conclusion

KN95 masks are a highly effective means of personal respiratory protection against airborne particles and viruses, but their performance is entirely dependent on three factors: authenticity, fit, and proper use. By choosing a certified mask from a reputable source, ensuring it forms a tight seal on your face, and following correct donning and doffing procedures, you can significantly enhance your personal safety. Remember, a high-quality mask with a poor seal offers little protection.