To tell if a KN95 fits, you should perform a user seal check to ensure no air leaks are present.
Ensuring a proper fit for your KN95 mask is crucial for maximizing its effectiveness in filtering airborne particles. A well-fitting mask creates a seal around your face, preventing unfiltered air from leaking in.
Checking the Seal: The Key Indicator
According to the reference provided, a proper fit is indicated by two main things:
- Facepiece Collapse: When you inhale sharply, the facepiece should slightly collapse on your face. This shows that the mask is tight enough for suction.
- No Air Leakage: Crucially, you should not feel air passing between your face and the facepiece at the edges (around your nose, cheeks, or chin) when you inhale or exhale.
If you feel air leaking, the mask is not forming a proper seal.
Performing a User Seal Check
Here's a common method to perform a user seal check:
- Put on the Mask: Place the mask over your nose and mouth, securing the ear loops or headbands.
- Adjust: Adjust the nose piece to mold it firmly across the bridge of your nose using both hands. Ensure the mask covers your chin.
- Check for Collapse: Inhale sharply. The mask should pull inward slightly towards your face.
- Check for Leakage:
- Positive Pressure Check: Exhale sharply but gently. Feel around the edges of the mask with your hands. You should not feel air escaping.
- Negative Pressure Check: Inhale sharply. The mask should pull towards your face, and you should not feel air coming in around the edges.
What if You Cannot Achieve a Proper Seal?
If you cannot achieve a proper seal due to air leakage, the reference states that you may need to be fit tested for a different respirator model or size.
This is a critical point. Not all mask styles or sizes fit everyone's face shape. If you try the seal check and detect leaks, consider:
- Readjusting the mask and nose piece.
- Trying a different brand, size, or shape of KN95 mask. Different designs have different fit characteristics.
- For occupational use or situations requiring guaranteed protection, professional fit testing can confirm if a specific mask model provides an adequate seal for your face.
Summary of a Good KN95 Fit
| Aspect | Indication of Good Fit | What to Avoid |
|---|---|---|
| Seal Confirmation | No air leaks felt around the edges when breathing. | Feeling air escape or enter the edges. |
| Mask Movement | Facepiece slightly collapses inward when inhaling sharply. | Mask staying rigid or not moving. |
| Coverage | Covers nose, mouth, and chin. | Gaps around the nose, cheeks, or chin. |
| Comfort | Fits snugly but comfortably without excessive pressure. | Pain, discomfort, or difficulty breathing due to poor fit. |
A successful seal check confirms that the air you breathe is primarily passing through the mask's filter material, offering the intended level of respiratory protection.
