Quantitative fit testing (QNFT)

When it comes to protecting workers from harmful airborne contaminants, ensuring a proper seal between a respirator and the wearer’s face is critical. One of the most reliable and objective ways to measure this seal is through Quantitative Fit Testing (QNFT).

What Is Quantitative Fit Testing?

Quantitative Fit Testing is a method used to assess how well a respirator fits an individual by providing a numerical value, known as a fit factor. This value indicates the effectiveness of the seal between the facepiece and the wearer’s skin.

Unlike qualitative fit testing—which relies on the user’s subjective senses (like taste or smell) to detect leakage—QNFT provides an objective, measurable result. This makes it especially valuable in environments where safety and compliance cannot be left to guesswork.

How Does QNFT Work?

During a QNFT, specialized instruments measure the concentration of microscopic particles both inside and outside the respirator while the wearer performs a series of exercises (e.g., turning the head, talking, or bending over). These movements simulate real-life conditions and help assess whether the mask maintains its seal during motion.

The fit factor is then calculated as the ratio of the concentration of particles outside the mask to the concentration inside. The higher the fit factor, the better the seal.

Applications of QNFT

QNFT is suitable for testing a variety of respirators, including:

• Disposable half masks (e.g., N95 respirators)

• Reusable half-face respirators

• Full-face respirators

  
  

This makes QNFT a flexible and essential tool in industries like healthcare, construction, manufacturing, chemical processing, and any field where respiratory protection is required.

Why QNFT Matters

1. Objective Results - QNFT removes subjectivity from the testing process, giving employers and safety professionals hard data to base decisions on.

2. Compliance and Regulation - Many regulatory bodies, including OSHA and other international safety organizations, recognize QNFT as a valid method for ensuring respirator fit.

3. Enhanced Protection - A respirator that doesn’t fit properly can expose workers to harmful particles. QNFT ensures that each mask provides the expected level of protection.

Contact us to find out more!