Qualitative vs Quantitive

Qualitative or quantitative fit testing; which method is best suited to the NHS?

Fit testing is a big headache for any busy NHS Trust and the sheer numbers of staff that require testing can sometimes feel overwhelming.  At Full Support Healthcare we have spent many years working with Infection Control Teams to provide education, training and problem solving to help NHS Trusts to become competent, confident and compliant in relation to HSE guidance in the area of Respiratory Protective Equipment (RPE) and fit testing.

As a company selling to Healthcare and Industry we commonly use both qualitative or quantitative methods of fit testing, matching the best method to the mask, the hazard and the environment where staff are required to work. In Healthcare FFP3 respirator masks are the ideal choice and the most widely used for protection against respiratory viruses, accounting for over 99% of all respiratory protection in the NHS.  They are single use and can easily be changed between the care of multiple patients. The qualitative method of Fit Testing in the Healthcare environment is the most suitable for a number of reasons.

The qualitative method of fit testing, conducted with Bitrex or Saccharine, is an excellent way of determine fit. 

  • It is a low cost and effective method of fit testing
  • No ongoing calibration or maintenance costs
  • Quick and efficient way to fit test multiple frontline staff
  • A simple and easy process requiring minimal training
  • Ensures staff become competent and confident fit testers

This method allows NHS Trusts to train the large bank of fit testers required to cascade fit testing to the thousands of frontline staff who require RPE.

A recent HSE paper highlighted the some considerations when choosing the best fit test method for FFP3 respirators;

‘The Bitrex qualitative fit test method has been shown to give a good determination of fit in this study. It may have the potential to give the most accurate determination of true fit as the challenge particles do not pass through the filtering material in a form which can be detected, a problem which can occur when using quantitative fit test methods.’

‘Both Portacount methods (without or with the N95-Companion technology) and the TIL method will be affected by challenge particles passing through the filtering material, leading to a less accurate (biased low) measure of fit.’

‘A further problem with the Portacount is that it cannot discriminate between particles; it will count all particles, whatever their origin or size, equally. This is especially a problem as some people can generate particles, particularly when they talk, and these will be counted in with the fit test sample from inside the FFP3, leading to a less accurate (biased low) measure of fit .¹‘

‘The Bitrex fit test method relies entirely on the taste response of the test subject to assess the fit. The test agent (Bitrex aerosol) does not pass through the filtering material in detectable form7, which means that by using this method one problem that occurs with quantitative methods is eliminated. However, the detection is entirely dependent on the test subject, their sensitivity to Bitrex and their judgement of whether or not they can taste Bitrex during the fit test.’

For respiratory protection against other particulates or chemical hazards please seek expert advice from a RPE specialist so they can recommend the correct respirator mask and filter combination.


¹. Review of fit test pass criteria for Filtering Facepieces Class 3 (FFP3) Respirators:  Prepared by the Health and Safety Laboratory for the Health and Safety Executive 2015


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