The Science Behind Face Fit Testing: How Particle Physics Impact RPE

Face Fit testing is a critical process that ensures tight-fitting Respiratory Protective Equipment (RPE), such as masks and respirators, provide an effective seal to the face of the wearer and so protect the wearer from harmful respirable hazards, such as dust, mists, fumes, gases and vapours. It involves an assessment of mask leakage around the face seal area to ensure that any leakage is not significant enough to impact the level of protection the mask or system is designed to provide.

In any safety test, it’s necessary to understand the nature of the risk – and that’s equally true in Face Fit testing. So, what’s the science behind RPE and how can understanding it help to improve the use of respiratory protection?

What Is Particle Physics?

Particle physics is a branch of physics that deals with particles' behaviour and properties, including those we breathe. Understanding particle physics can help scientists improve the performance of RPE and develop more effective equipment for use in hazardous environments.

RPE is designed to protect workers from airborne particles, such as dust and mist, which can pose health risks. These particles occur in different sizes and shapes, and their behaviour can affect how effectively RPE performs. For example, the size of a particle determines how easily it can penetrate a filter or mask material: smaller particles, such as fine dust or aerosols, can be more challenging to capture and may require specialised filtration techniques. Understanding the properties and behaviour of particles allows researchers to develop more effective filter materials and mask designs to provide optimal respiratory protection.

How Particle Physics Improves Mask Efficiency Testing

Particle physics research also contributes to developing techniques for measuring RPE performance. Traditionally, Face Fit testing has been used to ensure that masks provide a proper seal; however, advances in particle physics have led to the introduction of innovative methods for evaluating efficiency.

One such technique is the use of particle counters, and laser-based particle detection methods can be used when Face Fit testing. For example, Fire Safe International are a distributor of the AccuFIT 9000, which employs cutting-edge particle counting technology to assess the fit of RPE. The device generates a controlled and constant flow of air, which passes through an alcohol-saturated wick and then a condensing chamber before entering a further chamber with a laser light source and detector. This Laser-based technology detects and counts any microscopic airborne particles.  Air is sampled from both inside and outside the mask, and by calculating the ratio of particles inside and outside, the fit factor of the mask or leakage rate can be determined. This approach provides a very accurate and objective evaluation of RPE fit, minimising errors that human factors might introduce.

AccuFIT 9000 Features

  • Rugged design for rapid deployment.
  • Features proven CNC Fit Testing technology for optimised particle counting efficiency.
  • Adaptable for all types of respirator, elastomeric and disposable respirators.
  • Conforms to HSE INDG479 Fit Test protocols and OHSA testing standards.
  • 7” colour touchscreen.
  • 3-year warranty.

Find Out More

To find out more about the AccuFIT 9000, please call Fire Safe International on 01743 761000.


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