Respirator User Seal Check: Positive and Negative Pressure Methods (2026)

Respirator User Seal Check: What It Is and How to Do It

A respirator user seal check is the self-performed test you must do every time you put on a tight-fitting respirator before entering a hazardous atmosphere. OSHA 1910.134 Appendix B-2 requires it. A passing seal check confirms the respirator is properly seated and the face seal is intact for that specific donning — it takes under 30 seconds and is your final verification before exposure.

A seal check is NOT a substitute for the annual OSHA fit test. The fit test (QLFT or QNFT) qualifies the respirator model for your face shape once a year. The seal check confirms proper donning every single time. See how to fit test a respirator and QLFT vs QNFT comparison for annual fit-test requirements.

What Is a User Seal Check?

The user seal check is a rapid test — positive pressure, negative pressure, or both — performed by the wearer immediately after donning a tight-fitting respirator. The goal is to confirm that the face seal has no leaks for that specific donning. A leak detected by the seal check indicates an improperly seated respirator that must be adjusted or replaced before entering any atmosphere requiring respiratory protection.

OSHA 1910.134 Appendix B-2 specifies two accepted methods: positive pressure and negative pressure. The manufacturer's recommended method should be used when available. In the absence of manufacturer instructions, either method may be used.

Step-by-Step: Positive Pressure Seal Check

The positive pressure check is performed on respirators with an accessible exhalation valve:

1. Ensure the respirator is properly donned — nosepiece formed, straps adjusted, chin positioned correctly.
2. Cover the exhalation valve with your palm or the valve cap (if provided). Do not press on the facepiece itself — hold only at the valve.
3. Exhale gently into the facepiece.
4. Pass: The facepiece bulges slightly outward with no air leaking around the face seal. You feel slight outward pressure inside the facepiece.
5. Fail: Air escapes at the face seal (you feel it on your cheeks, chin, or around your nose). Adjust and repeat.

If the positive pressure check fails after adjustment: (1) re-form the nosepiece; (2) re-tension the straps; (3) reposition the chin in the chin cup; (4) try a different size or model.

Step-by-Step: Negative Pressure Seal Check

The negative pressure check is the standard method for disposable N95s and works for cartridge respirators too:

1. Ensure the respirator is properly donned.
2. Cover the inhalation ports (cartridge inlets, or the entire facepiece for disposables) with both palms. Do not press on the facepiece — cup your hands loosely.
3. Inhale gently.
4. Pass: The facepiece collapses slightly inward and holds steady. No air enters around the face seal. You feel suction holding the mask against your face.
5. Fail: Air enters around the face seal (you hear or feel inflow at the edges). Adjust and repeat.

Seal Check for Disposable N95 Respirators

Disposable N95 respirators (from the N95 collection) do not have separate inhalation ports to close, so the negative pressure check is performed by cupping both hands over the entire facepiece:

1. After donning, cup both hands over the facepiece without disturbing it.
2. Inhale sharply.
3. Pass: The respirator pulls inward slightly — you feel it tighten against your face with no air entering around the edges.
4. Fail: Air enters around the nose bridge, cheeks, or chin. Re-form the nosepiece, re-adjust straps, and repeat.

If the N95 seal check fails after adjustment, try a different N95 model or size. See respirator sizing guide for sizing guidance and fit test requirements for the annual OSHA fit-test requirement.

Common Causes of Seal Failure

• Facial hair at the sealing surface — even a single day's growth can break the seal; see respirator with beard guide for compliant alternatives
• Eyeglass temple bars — pass through the face seal; see respirator with glasses guide for solutions
• Deformed nosepiece — nosepiece not formed to nose shape; reform before retesting
• Wrong size or model — use sizing guide and fit test to find the correct respirator
• Damaged sealing surface — cracks, hardening, or contamination of the face seal material
• Strap tension — too loose (leaks at edges) or too tight (distorts the sealing surface)
• Chin not in chin cup — full-face respirators require the chin to be fully seated in the chin cup

Seal Check: Frequently Asked Questions

What is a respirator user seal check?

A user seal check is a quick test performed by the respirator wearer at every donning to confirm the respirator is properly seated and sealed for that use. OSHA 1910.134 and its Appendix B-2 require users to perform a seal check each time the respirator is put on. A seal check does NOT substitute for formal annual fit testing — it only confirms proper donning for that session. See fit testing guide for the annual OSHA requirement.

What is the positive pressure seal check?

In the positive pressure user seal check, the wearer closes off the exhalation valve (typically by covering it with a palm or the provided cap), then exhales gently. If the facepiece bulges slightly and no air escapes around the face seal, the respirator is properly seated. Any detectable outward airflow at the face seal indicates a leak. This method is appropriate for respirators with an accessible exhalation valve. Note: many disposable N95 respirators do not have a separate exhalation valve.

What is the negative pressure seal check?

In the negative pressure seal check, the wearer closes off the inhalation ports (covering the air intakes on a cartridge respirator, or covering the entire facepiece on a disposable), then inhales gently. If the facepiece collapses slightly inward and holds — no air enters around the face seal — the respirator is properly seated. Any inward airflow at the face seal indicates a leak. This is the standard method for disposable N95 respirators.

How do I perform a seal check on an N95 respirator?

For an N95 disposable respirator: (1) cup both hands over the facepiece without disturbing its position; (2) inhale sharply — the respirator should collapse slightly toward your face with no air leaking around the edges. If air leaks: re-adjust the nosepiece, re-position the straps, and repeat. If leakage persists, try a different size or model. See respirator sizing guide and annual fit test requirements for N95 fit testing.

Is a seal check the same as a fit test?

No. A fit test (QLFT or QNFT) is a formal OSHA-required annual test with prescribed exercises and challenge agents, performed by a trained tester, establishing that a specific respirator model fits a specific wearer. A seal check is a quick self-check performed at every donning to confirm proper seating for that use. Seal checks catch donning errors; fit tests qualify the respirator-wearer match. See QLFT vs QNFT guide for fit test methods.

When should I perform a user seal check?

OSHA 1910.134 Appendix B-2 requires a user seal check each time a tight-fitting respirator is donned. Additional seal checks should be performed: after adjusting the respirator during a work session; after any event that might displace the respirator (sneezing, coughing, speaking extensively); and when re-donning after removal. Seal checks are mandatory before entering any atmosphere requiring respiratory protection.

What causes a respirator seal to fail?

Common causes of seal failure confirmed by a failed seal check: (1) facial hair at the sealing surface — see respirator with beard guide; (2) eyeglass temple bars passing through the sealing surface — see respirator with glasses guide; (3) bent or improperly formed nosepiece; (4) incorrect strap tension (too loose or too tight); (5) wrong respirator size; (6) damaged or worn sealing surface; (7) foreign material (sweat, makeup, grease) at the seal.

Can I adjust the respirator if the seal check fails?

Yes. If the seal check fails, adjust the nosepiece, strap tension, and position of the respirator, then repeat the seal check. Do not enter a hazardous atmosphere until a proper seal is confirmed. If adjustment does not resolve the leak, try a different respirator size, style, or model. OSHA prohibits using a respirator known to have an inadequate seal.

Do exhalation valve respirators use positive or negative pressure seal checks?

Respirators with exhalation valves use the positive pressure check — cover the exhalation valve and exhale to check for leakage around the face seal. The inhalation ports (cartridges) provide the resistance for the negative pressure check on the inhalation side. Many employers train workers to perform both checks on valved respirators: positive (exhalation valve covered) and negative (inhalation ports covered).

Does a seal check work for full-face respirators?

Yes. Full-face respirators (like the 3M 6800) use the same seal-check principles: positive pressure check by covering the exhalation valve and exhaling, negative pressure check by covering the inhalation ports and inhaling. Full-face respirators have a larger sealing surface — pay particular attention to the seal at the forehead, temples, and chin. The chin cup design must be properly positioned below the chin, not resting on it.

How do I store a respirator to protect the sealing surface?

Store tight-fitting respirators in a clean, dry location away from contamination, sunlight, and temperature extremes. Use the original storage bag or a dedicated container. Do not fold the respirator in a way that deforms the facepiece or face seal. Do not store with the sealing surface against rough surfaces. Inspect the sealing surface before each use — cracks, hardening, or deformation of the sealing material requires replacement.

What is the difference between a user seal check and a fit check?

The terms are often used interchangeably. OSHA 1910.134 uses "user seal check" (Appendix B-2); some manufacturers and trainers use "fit check." Both refer to the same self-performed positive/negative pressure test done at donning. Neither is a substitute for the formal annual OSHA fit test (QLFT or QNFT).

Should I perform a seal check on a PAPR (powered air-purifying respirator)?

PAPRs with loose-fitting hoods or helmets do not require a seal check or fit test because they are not tight-fitting. PAPRs with tight-fitting facepieces require fit testing and seal checks following the same procedures as other tight-fitting respirators. Check the PAPR manufacturer's instructions to confirm your hood/helmet type and whether a seal check applies. See the PAPR collection for tight-fit vs loose-fit PAPR options.

Can I use a respirator after a failed seal check by wearing it differently?

Not in a hazardous atmosphere. If adjustments do not produce a passing seal check, the respirator must not be used for the intended application until a satisfactory seal is achieved. Alternative actions: (1) try a different respirator size; (2) try a different respirator model; (3) use a loose-fitting alternative (PAPR hood) where the hazard allows; (4) implement engineering controls to reduce exposure. Document failed seal checks and the corrective actions taken.

Do N95 disposables require a seal check?

Yes — OSHA 1910.134 requires a user seal check each time any tight-fitting respirator is donned, including disposable N95s. The standard method for disposable N95 is the negative pressure check (cup hands over facepiece, inhale sharply, confirm the respirator collapses slightly with no leakage around the edges). Adjust and repeat if leakage is detected. See N95 respirator collection and sizing guide for fit-related N95 selection.