The importance of Mask Fit Testing: Unveiling the perfect fit

27th Feb 2024

Discover the importance of Mask Fit Testing in our latest blog. Learn why finding the perfect fit matters for your safety and well-being.

the importance of mask fit testing

A mask fit test is crucial for ensuring respiratory protection equipment is effective. Including respiators such as FFP3, in preventing the inhalation of harmful airborne particles. The method involves assessing the seal and fit of the mask on an individual’s face to minimise the risk of exposure to contaminants. In this blog post, we delve into the crucial role of mask fit testing and why it’s key to ensuring optimal protection in today’s challenging times.

Importance of Mask Fit Testing

Ensuring effective protection:

A mask’s effectiveness in filtering out airborne particles relies heavily on how well it fits the wearer’s face. When the mask is sealed properly, air passes through the filtration material instead of leaking out.

Minimising exposure to harmful substances:

In environments such as healthcare facilities, construction sites, or industrial settings, exposure to airborne contaminants is common. Therefore, mask fit testing is crucial! Mask fit testing helps minimise the risk of inhaling harmful substances such as dust, chemiclas, fumes, etc.

Reducing occupational hazards:

For workers in high-risk occupations, such as healthcare workers, builders, firefighters, or industrial workers, proper respiratory protection is essential for their safety. A mask fit test ensures that these individuals are adequately protected against inhaling hazardous substances.

Compliance with regulations:

In the United Kingdom, mask fit testing is regulated primarily under the Control of Substances Hazardous to Health (COSHH) Regulations 2002. These regulations require employers to control exposure to hazardous substances, including airborne contaminants, to protect the health of employees.

Preventing spread of infection:

In healthcare settings, where preventing the transmission of infectious diseases is paramount, mask fit testing ensures that healthcare workers wear masks that provide a reliable barrier against respiratory droplets containing pathogens like bacteria or viruses.

Optimising comfort and wearability:

Properly fitted masks are more comfortable to wear for extended periods, reducing the likelihood of wearers adjusting or removing their masks, which could compromise their effectiveness and increase the risk of exposure to contaminants.


And finally cost-efficiency. By ensuring individuals are wearing masks that fit properly, mask fit testing helps optimise the use of respiratory protective equipment, reducing waste and unnecessary expenses associated with ill-fitting masks.


Types of Testing:

There are two main methods of mask fit testing: qualitative and quantitative.

Qualitative Fit Testing

Individuals use qualitative fit testing as a method to assess the adequacy of a mask's fit on their face by relying on their sense of taste to detect any leakage or airborne contaminants. This method can be used to fit ½ face FFP3 respirators.

Quantitative Fit Testing

Quantitative fit testing is a method use to quantitatively measure the effectiveness of a mask or respirator in forming a seal around the wearer’s face. Unlike qualitative fit testing, which relies on subjective indicators like taste or smell, quantitative fit testing involves the use of specialised equipment to measure the concentration of airborne particles inside and outside the mask.  This method can be used to fit both ½ face and full face FFP3 respirators.


The main differences between Qualitative and Quantitative Fit Testing 

Method of Evaluation

Qualitative fit testing relies on the wearer’s subjective response to detect leakage of the test agent. While wearing the mask, the wearer will perform various different exercises including:

  • Normal breathing
  • Heavy breathing
  • Moving their head side to side
  • Moving their head up and down
  • Counting form 100 backwards
  • Bowing forward and backwards

They will then indicate whether they can taste the test agent.

Quantitative fit testing utilises specialised equipment to objectively measure the amount of leakage into the mask. This is typically done by comparing the concentration of particles inside the mask to the concentration outside the mask, using a particle counting device such as PortaCount machine.

Subjectivity vs Objectivity

As qualitative fit testing relies on the wearer’s subjective perception of taste, this can make it more prone to variability and subjectivity. It depends on the wearer’s ability to detect the test agent, which may vary between individuals.

On the other hand, quantitative provides an objective measurement of mask fit, as it quantifies the amount of leakage numerically. This makes it less susceptible to individual interpretation and more consistent in assessing mask fit across different wearers.

Types of Tests

Regarding qualitative fit testing, common methods include Bitrex (bitter taste), or Ssccahrin (sweet taste). The wearer's breathing zone recieves the introduction of these substances.

The wearer then  indicates whether they can taste them while performing specialised exercises.

However, quantitative fit testing includes ambient aerosol, controlled negative pressure, and controlled positive pressure tests. These tests use specialised equipment to generate a consistent aerosol or particulate challenge, measure particle concentrations inside and outside the mask, and calculate a fit factor based on the ratio between the two.

Suitability and Accuracy

Qualitative is generally considered suitable for half-face respirators and filtering facepiece respirators but is not accurate, or suitable, for full-face respirators or respirators with high-efficiency filters.

Quantitative is typically recommended for all types of respirators, including half-face, full-face, and powered air-purifying respirators, as it provides a more accurate and objective assessment of mask fit, especially for respirators with high-efficiency filters.

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