N95 Masks: All About Their Fitting

N95 Masks: All About Their Fitting


Major world health organizations recommend the use of waterproof respirators and N95 protective masks. The N95 is a protective mask with a fine mesh synthetic polymer filter. The number 95 means that the mask filters out 95% or more of airborne particles, including splashes that may contain bacteria or viruses such as COVID-19.

The CSA Z94.4 standard requires that all workers undergo a fit test before wearing a respirator for the first time. Respirator users must be fit-tested at least every two years, when there is a change of equipment, or even a physical change, such as weight loss.

Respiratory protection program

In a company where the use of respiratory protection is necessary, it is mandatory to have an up-to-date respiratory protection program. A corporate respiratory protection program should indicate the protections available to workers.

A comprehensive respiratory protection program requires several elements. Procedures should be in place for:

  • The selection of respirators suitable for the task
  • The proper use of respirators
  • The definition of worker roles and responsibilities
  • Fit testing

Additional elements may be added:

  • Establishing procedures for the inspection, cleaning, storage and disinfection of respirators.
  • Creation of unit and job lists requiring respirators, with the inventory of respirators required for each function.
  • Implementation of training sessions for employees regarding the proper use and removal of respiratory protective equipment.
  • Implementation of a process to evaluate the effectiveness of the programs.
  • The implementation of a medical surveillance program.
  • Keeping a record about employees and their mask model and size, as well as the date of their last fit test.

Qualitative fit testing

Respirator fit testing is essential to a well-constructed protection program. Qualitative testing is based on the subjective taste and reaction of the person being tested. The user will use their senses to detect the infiltration of a substance inside and determine if the facepiece is tight.

Before beginning the fit test, the industrial hygienist or technician will conduct a taste test by placing a test hood over the individual's head. Wearing disposable gloves, the hygienist pumps 10 puffs of sensitivity test solution into the hood and the individual indicates when he or she will taste the substance.

This taste test is performed to ensure that the worker can taste the solution, and thus determine the concentration level of the substance to be used in the fit test. The mask is then properly fitted to the individual's face. No taste should be detected during this test to ensure that there are no leaks.

Some models of disposable respirators are equipped with a built-in exhalation valve that allows hot air to escape so that the lenses of eye or safety glasses do not fog up.

Fogging on glasses, masks, or face shields does not necessarily indicate a leak in the respirator. If this problem persists, a defogging solution may be considered.

Pandemic-related issues

The industrial hygienist or technician must be prepared to deal with some of the challenges arising from the current situation:

  1. The test hood must be properly cleaned and disinfected before and after each use. Wearing a test hood that has already been worn may be a concern for some, especially during an infectious disease outbreak.

  2. The current pandemic is causing inventory shortages of N95 disposable masks. The many known respirator manufacturers are unable to meet the enormous demand, even with their increased production.

  3. Ideally, the choice of respirators should be varied and adapted to different tasks or jobs, but the reality is that during this pandemic period, not all types of respirators are available.

  4. Wearing a mask cannot interfere with a worker's eye protection. The key is to find a respirator that fits the shape of the individual's face and maintains an effective seal at all times.

Did you know that we specialize in the fit testing of respirators? Learn how to ensure that your respiratory protective equipment actually protects you and your workers here! We also offer respiratory protection training. Learn more here.

Authorities have called for rigorous and judicious management of the use of N95 masks to address a potential shortage. The following links will keep you informed of developments.

1. https://www.canada.ca/en/public-health/services/diseases/coronavirus-disease-covid-19.html

2. https://www.canada.ca/en/health-canada/services/drugs-health-products/medical-devices/masks-respirators-covid19.html