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Respiratory Protection

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Organizations and employers are obligated to protect workers from exposure to a hazardous biological or chemical agents in the air when other hazard control methods are not practical or possible to put in place. 

They should only be used:

  • When following the -hierarchy of control- is not possible (e.g., elimination, substitution, engineering or administrative controls)
  • While engineering controls are being installed or repaired
  • When emergencies or other temporary situations arise (e.g., maintenance operations)


Respiratory hazards may be present as 

  • Particulates
  • Gases
  • Vapours
  • Fumes
  • Mists
  • Dusts Bioaerosols (e.g., moulds)

Inhalation hazards can be divided into the following classes based on the type of effects they cause.

1. Irritants.
Materials that irritate the nose, eyes, lungs or throat. Some of these materials include solvent vapours, fibreglass dust, ozone and hydrogen chloride gas. Pulmonary edema, a pneumonia-like condition, can present after several hours from being exposed to materials like cadmium fume produced by welding or oxyacetylene cutting of metals coated with cadmium.
2. Asphyxiants.
Substances that do not allow proper oxygenation to the body and can be divided into simple asphyxiants (displaced oxygen by gases or vapours), or chemical asphyxiants (elements that interfere with the body’s ability to transport oxygen).

3. Central nervous system depressants.
Cause symptoms such as headache, drowsiness, nausea, and fatigue. Most solvents are central nervous system depressants. 
4. Fibrotic materials.
Asbestos and Silica can cause fibrosis or scarring of lung tissue in the air sacs. 

5. Carcinogens.
Asbestos, Silica and Hexavalent Chromium can promote or cause cancer in specific body organs. 

6. Dusts.
Excessive exposure to these substances can be adverse in itself or can aggravate existing conditions such as emphysema, asthma, or bronchitis. 

7. Biological hazards.
Can cause asthma, throat, nose and eye irritation or pneumonitis. 

8. Respiratory sensitizers.
Asthma can be caused by chemicals such as isocyanates in spray foam insulation or certain wood dusts.


Supervisors/Principal Investigator and All Others in Authority
Supervisors/Principal Investigator and all others in authority shall:

  • Identify situations where respirators are required
  • Conduct an assessments for respiratory hazards
  • Determine the type of respiratory protection required for the specific respiratory hazard.
  • Ensure that user screening, training and fit testing, and, where required, medical assessments are completed prior to assigning a worker any task that requires the use of a respirator
  • Provide workers with appropriate respiratory protection
  • Ensure workers use the respirators in accordance with the instructions, the training received, and the safe operating procedures established for the workplace
  • Ensure workers wear appropriate respiratory protection at all times in respiratory hazard areas
  • Ensure that workers use only those respirators for which they have been trained and fit-tested for
  • Ensure respirators are cleaned, sanitized and decontaminated when required, inspected, maintained, repaired, and stored in accordance with training and manufacturer’s recommendations
  • In case of a tight-fitting facepiece, ensure respirator users are clean-shaven and do not have any object or material that would interfere with the seal or operation of the respirator 
  • Provide details of the type of respirator selected and the anticipated working conditions to the health care professional conducting the medical assessment of a respirator user

Respirator Users 
Respirator Users shall:  

  • Wear appropriate respiratory protection at all times when performing tasks or working in an area where respiratory hazards exist
  • Inspect the respirator to ensure it is clean and in good operating condition prior to each use and at intervals that will ensure that it continues to operate effectively
  • Clean, maintain and store the respirators in accordance with the training received and the manufacturer’s instructions
  • Perform negative and positive pressure/seal checks after each donning of a tight-fitting respirator
  • Remove from service any respirator that they determine to be defective and report it to their supervisor
  • Report to their supervisor or other person in authority any condition or change that may impact their ability to use a respirator safely
  • When using a tight-fitting facepiece respirator, be clean shaven and ensure that no object or material interferes with the seal or operation of the respirator
  • Use the respirator in accordance with the manufacturer’s instructions, written instructions and training received


What is NIOSH?
The National Institute for Occupational Safety and Health (NIOSH) is the U.S. federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH conducts scientific research, develops guidance and authoritative recommendations, disseminates information, and responds to requests for workplace health hazard evaluations. Where there is a danger of an airborne hazardous substance or an oxygen deficient atmosphere in a workplace, the employer shall provide a respiratory protective device that is listed in the NIOSH Certified Equipment List.

What is CSA Z94.4?
The Canadian Standards Association is the most widely accepted regulatory agency in Canada. CSA is an independent, not-for-profit membership association that encompasses standards development, training and advisory solutions, global testing and certification services, as well as consumer product evaluation services. Currently 40 per cent of all the standards issued by CSA are referenced in Canadian legislation CSA Z94.4.1:21 provides a classification for respirator types and performance criteria for respirator certification. It follows the requirements in 42 CFR 84 approved by the National Institute for Occupational Safety and Health (NIOSH) in the United States. The Canadian standard and accredited certification program provides manufacturers with an equivalent option to the U.S. NIOSH certification program for filtering respirators. Eventually, this certification program will replace the Health Canada Guidance on safety and performance specifications for filtering facepiece respirators (FFRs) issued during COVID-19 in 2020. 

Comparing CSA Z94.4.1:21 with NIOSH (42 CFR 84):
A primary objective of CSA Z94.4.1:21 was to align the Canadian standard to NIOSH requirements. CSA also took the opportunity to address some of the specific needs and requirements identified during COVID-19. Some of the key additions include:

  • Airflow resistance and breathability: New classes with lower airflow resistance were introduced to address breathability and comfort.
  • Fluid and flammability resistance: New class for fluid and flammability resistance to address medical and surgical applications.
  • Shelf life: Requirement included for manufacturers to provide validation of a given lifetime. 

CSA Z94.4.1:21 excluded gas/vapour and CBRN filtering respirators, such as:

  • self-contained breathing apparatus (SCBA)
  • gas masks chemical cartridge respirators
  • special use respirators, andclosed-circuit escape respirators.
NIOSH 42 CFR 84 Standard Requirements
CSA Z94.4.1:2021 Standard Requirements
Filter performance (must be ≥ X% efficient): ≥95%
Filter performance (must be ≥ X% efficient): ≥95%
Testing agent: NaCL
Testing agent: NaCL
Flow rate: 85 L/min
Flow rate: 85 L/min
Inhalation resistance - max pressure drop: ≤ 343 Pa
Inhalation resistance - max pressure drop: Three levels: ≤ 100 Pa, ≤ 175 Pa, ≤ 343Pa
Exhalation resistance - max pressure drop: ≤ 245 Pa
Exhalation resistance - max pressure drop: Three levels: ≤ 100 Pa, ≤ 175 Pa, ≤ 245 Pa
Inhalation/ exhalation resistance: No requirement to mark or inform the user of the degree of inhalation/ exhalation, which is a factor for breathability.
Inhalation/ exhalation resistance: Requirement to add a suffix to the particulate filtration designation to inform users if the inhalation/ exhalation testing falls within 3 levels of breathability (from more difficult/ higher resistance results to easier breathability/ lower resistance results)
Fluid resistance: FDA Clearance for surgical use (including fluid/ flammability testing) is additional to 42 CFR 84.
Fluid resistance: Fluid/flammable resistance is included as a respirator class.
Shelf life: No requirement
Shelf life: Designation and validation of shelf life for filters and integrated respirators, optional for other components.
Marking/ labelling: N95/99/100
Marking/ labelling: CA-N95/N99/N100. L replaced by F for surgical respirators and only 1 level so no number added.


If any worker needs to use a respirator, then a respiratory protection program is
necessary. The program should include the following procedures for:

  • Hazard identification, assessment, and control.
  • Selection and use of respirators.
  • Respirator user training.
  • Respirator fit testing.
  • Inspecting, cleaning, maintaining and storing respirators.

In addition, CSA standard Z94.4 requires that the employer ensure the individual is medically approved to wear a respirator. It is important to refer to the occupational health and safety legislation in your jurisdiction for additional requirements for respirator use.


Oxygen levels can determine if an atmosphere is oxygen-deficient or oxygen-enriched.

Above 23%
There is an extreme risk of fire hazards possible in an oxygen-rich atmosphere
Generally the maximum "safe" oxygen level, however, some jurisdictions allow up to 23.5%
The average concentration in air
The minimun safe oxygen level in most provincial jurisdictions
The minimum safe oxygen level in federal jurisdictions
Impaired judgment can be detected
The first sign of anoxia (lack of oxygen to the organs) begins
Breathing and pulse rates being to increase and abnormal fatigue and emotional upset can occur
Nausea, vomiting and loss of consciousness can occur
6% or less
Results in convulsions, respiratory failure and heart failure

Oxygen-rich environments (above 23%) have flammable hazards that relate directly to firefighting, hazmat response and operations, and confined space entry.


Filters and cartridges enhance the effectiveness of respiratory protection. Advanced planning and consideration must be given when choosing a filter or cartridge. Particulate filters are available in three classes known as N, R and P.
Each class can provide three levels of filter efficiency: 
1. 95%
2. 99%
3. 99.97%

N-Class (Non-Oil)
N-class filters are for non-oil atmospheres only. This means they will not provide protection in oily atmospheres.

R-Class (Somewhat Resistant to Oil)
R-class filters are resistant to oily atmospheres but must be time monitored with a maximum of eight hours of service.

P-Class (Oil Proof)
P-class filters are oil proof and may be used in oil-containing atmospheres like underground mines and machine shops.

How to Choose a Filter:

  • Decide on the filter efficiency required for  the task
  • Consider if the aerosol  contains oil. If not,  you can use an  N-class filter.

N95 Filtering Facepiece
The N95 filtering facepiece is one of the most popular respirators on the market. You can use N95 pre-filters with chemical cartridges, as well as R pre-filters and standalone P-class filters.

Pre-filters are N-series or R-series filter disks held to the top of a chemical cartridge by a filter holder. They are designed to filter particulates before air enters the cartridge.

N95s filter 95% of particulates > 3 microns in size. 

They are typically worn to reduce exposure to bioaerosols or droplets produced by coughing and sneezing. 

An N95 filtering facepiece respirator seals tightly and reduces exposure to smaller airborne particles. It forces inhaled air through a filter and must be fit tested to the user. Additional information on fit testing is found later in this guide. 

N95 filtering facepiece respirators cannot be used:

  • In oily atmospheres
  • In atmospheres containing less than 19.5%  oxygen
  • In Immediately Dangerous To Life or Health (IDLH) atmospheres, or
  • By users with facial hair or other conditions that may affect the seal between the face and  respirator.


To help select the correct respirator cartridge, NIOSH created a colour coding system.

Air-Purifying Respirator Cartridges Cartridges and filters provide protection against a specific type of hazard. The P100 filter is the most common type of cartridge. It's used for low-level concentrations of certain toxic dust including asbestos, radionuclides and silica.

P100 can be a standalone cartridge or stacked with the following:

  • Organic Vapour Cartridges that are approved for concentrations not to exceed 1,000 parts  per million for many organic solvents,  petroleum distillates and alcohols
  • Acid Gas/Mist Cartridges for atmospheres containing low levels of mineral acid gas  or mist
  • Ammonia and Methylamine Cartridges primarily used for ammonia
  • Multi-Contaminant Cartridges for environments with more than one  contaminant present (e.g., organic vapours or acid gasses)
  • Mercury Cartridges which are standalone only and are used for protection against low levels  of metallic mercury vapours
Color Code on Cartridge/ Canister
Acid Gases
Organic Vapor
Ammonia gas and Methylamine
Acid Gases and Organic Vapor
Multi-Contaminant and CBRN Agent
Mercury vapor, Chlorine and Sulfur Dioxide


A qualified person must establish written procedures and schedules to outline how often workers should change cartridges and filters based on warnings that determine an end-of-service time.

The useful service life of a cartridge is based on how long it provides adequate protection from hazardous air contaminants. The service life of a cartridge depends on many factors including:

  • Environmental conditions
  • Breathing rate
  • Cartridge filtering capacity
  • Contaminant quantity in the air.

Employers should apply a maximum use time to the service life estimate. This ensures the change-out schedule is based on a conservative estimate. 

Manufacturers have technical documents and tools to assist qualified persons when estimating maximum use time limits. These documents give instant access to contaminant and concentration data and other customized information.

Manufacturers also provide visual saturation indicators to let the user know when it's time to replace a cartridge.

The user can tell a cartridge needs changing based on warning properties and breathing resistance. For instance, if the hazard is a gas or vapour, the substance may be detected by smell or taste. This lets the user know that there has been a cartridge breakthrough. This however cannot be used as the sole method of cartridge change out.

If the hazard is a particulate, increased breathing resistance through the filter is the main way to determine that a change out is required.


The purpose of a qualitative or quantitative fit test is to verify a user’s ability to obtain an effective seal and an acceptably comfortable fit for a selected tight-fitting respirator. The fit test process also verifies that a user is able to demonstrate the required level of competency in donning and doffing the respirator, as well as inspecting it and performing a user seal check.  

  1. Respirator users must pass an appropriate quantitative or qualitative fit test when using a respirator with a tight-fitting face piece.
  2. Fit testing shall be conducted by a qualified provider which follows CSA Z94.4.21.
  3. The fit tester shall be competent in the applicable fit test methods and be able to verify a user’s ability to obtain an effective respirator seal, comfort, and fit for a tight-fitting respirator.
  4. The respirator user must demonstrate the required level of competency in donning and doffing the respirator, as well as inspecting and performing a user seal check without assistance.
  5. A fit test shall be carried out
    1. prior to initial use of a tight-fitting respirator
    2. after completion of the Respiratory Protection training
    3. after completion of the Respirator User Screening Form
    4. at least every 2 years
    5. when there is a change in respirator (e.g. make, model, or size)
    6. when a respirator user experiences continued significant discomfort during use or difficulty in completing a successful user seal check
    7. when there is a change in PPE use that could affect the respirator
    8. when changes to the user’s physical condition could affect the respirator fit such as (but not limited to):
      • facial scarring
      • dental changes
      • cosmetic surgery
      • significant weight change
      • facial rash (dermatological condition)
  6. The respirator user shall be fit tested with the same make, model, style and size of respirator to be used. 
  7. Assessment of comfort and appropriateness of fit shall be completed prior to the fit test.
    The respirator user will be asked to complete a comfort assessment scoring according to the following criteria:
    0 – No issues.
    1 – Discomfort that can be ignored.
    2 – Some discomfort but still able to function.
    3 – Unacceptable discomfort – not bearable.
    1. A score of 2 will prompt the fit tester to initiate a new re-donning or re-positioning or to use an alternative respirator option.
    2. A score of 3 shall result in rejection of the respirator worn.
    3. After passing the fit test, the respirator user shall be further assessed regarding the comfort of the respirator through the following question: Does this specific respirator provide you an acceptable comfort level for the scope of your work? Yes or No.
  8. The fit test shall only be performed on respirator users who are clean-shaven where the facepiece seals to the skin.
  9. When a worker is required to wear other personal protective equipment, such as eye, face, head and hearing protection during his/her course of work, the same protective equipment shall be worn during the fit test to ensure they are compatible with the respirator and does not break the facial seal
  10. A respirator fit-test card can be issued upon the respirator user upon successful completion of training and fit-test. The fit test card indicates the respirator manufacturer, model, size, and expiry date.
  11. The respirator user must only use the specific respirator (same manufacturer, model, and size) he/she was successfully fit tested with.

General Considerations
There are a few general points to consider when it comes to respirators and fit testing: 

  • Respirators must fit properly to provide adequate protection.
  • One size generally will not fit all.
  • Most manufacturers offer several facepiece sizes.
  • In some cases, no size from one manufacturer may fit a worker and a different brand may be necessary.
  • The user should be clean-shaven to ensure an effective seal.
  • A person should never be assigned a respirator without completing a qualitative or quantitative fit test. 
  • The results of fit testing must indicate the user has achieved an adequate seal.

A fit test must be carried out: 

  • After user screening and training. 
  • Before initial use of a tight-fitting respirator.
  • When changes to a user’s physical condition could affect the respirator, for instance, significant weight loss or gain, or changes to facial or dental features.
  • When there is a change to the actual respirator, for example, the make, model or size. 
  • When a respirator user experiences continued discomfort or has difficulty completing a successful seal check.
  • When there is a change in personal protective equipment that could affect the respirator.
  • At least every two years.

User Seal Check
A user seal check is an action conducted by the respirator user to determine if the respirator is properly sealed to the face. The user seal check can be conducted by doing one of the following tests: 

Positive pressure test: 

  • Block the exhalation valve, usually located on the bottom of the respirator.
  • Gently breathe out: The facepiece should puff slightly away from the user’s face without breaking the seal and stay like that while the user holds their breath.

Negative pressure test: 

  • Block the air inlets. These are usually the filter openings on the sides of the facepiece. 
  • Try to breathe in: If there are no leaks, the facepiece should collapse slightly and stay like that while the user holds their breath.

If a leak is detected, adjust the facepiece or straps and repeat the test until a good fit is achieved.

The users seal should be done prior to every use.

Important: A user seal check cannot be used as a substitute for a quantitative or qualitative fit test.


Qualitative fit testing relies on the user’s sensory response to detect a challenge agent in order to determine the fit of the respirator.

During qualitative fit testing, a challenge agent is introduced under a confined hood near the user to determine the integrity of the seal. 

The user must perform a series of head and body motions typical of normal daily movement. If the aerosol is undetected to the user on completion of testing, the seal is considered adequate and the test is considered successful. A pass is given to the user with the tested respirator only.

When QLFT is performed, a variety of fit testing challenge agents may be used. The most common types found in the latest Standard are:

  • Banana oil because of its aroma. 
  • Saccharin, a sweet-tasting agent.
  • Stannic chloride (otherwise known as irritant smoke). 
  • Denatonium benzoate (also known as Bitrex™) leaves a very bitter taste in the user’s mouth if the mask does not fit properly.

Successful Test Results

Users should refrain from the following activities for at least 30 minutes before testing to help ensure a successful process:

  • Smoking 
  • Ingesting sweet, bitter or spicy foods
  • Drinking coffee, tea or soft drinks.

Facial Hair

Individuals getting a fit test must be clean-shaven where the respirator seals to the skin of the face or neck.

For most, this means being clean-shaven within the previous 24 hours, but 12 hours is preferred.

This ensures hair won't infringe on the sealing surface of the respirator and won't interfere with the valve or respirator function.

It's best to put a clean-shaven policy in place by emphasizing its importance during training, regular reminders and ongoing conformance verification.

Important: If you cannot achieve a proper fit, do not enter the contaminated area and advise your manager or supervisor.


Quantitative fit testing uses an instrument to assess the amount of leakage into a respirator to determine fit.

During a quantitative fit test, ambient airborne particles are used as the challenge agent. These particles are measured both inside and outside the respirator while the test subject performs a series of exercises described in the CSA Standard. The particles may be counted by an optical particle counter (OPC) or condensation nuclei counter (CNC) to determine the number of particles inside and outside the respirator.

The instrument will sample for particles inside and outside the test subject’s mask simultaneously while determining a ratio.

A fit test pass is determined if:

  • The ratio is above the minimum test limit 
  • A high enough fit factor has been achieved
  • The user has completed a series of tests similar to the qualitative protocol.

This method removes any subjectivity on the part of the user and is considered the most reliable method of fit testing.


Respirator selection shall be based on a systematic review of the hazards and knowledge of standards, regulatory criteria, and manufacturer information on the types of respirators and their limitations to ensure that appropriate respirators are selected for the intended conditions of use.  

For the purpose of selection, respirators shall be grouped as follows:  

  1. Atmosphere-supplying respirators:
    1. Self-contained breathing apparatus (SCBA) (pressure-demand, open or closed-circuit)
    2. Airline or supplied air breathing apparatus (SABA) (pressure-demand or continuous-flow)
    3. Multi-functional (a configuration incorporating both SCBA and airline)
  2. Air-purifying respirators (APR), non-powered and powered (PAPR):
    1. Gas- and vapour-removing
    2. Particulate removing
    3. Gas-, vapour-, and particulate-removing
    4. Multi-functional (a configuration incorporating both APR and PAPR)
  3. Combined respirator (a configuration incorporating both atmosphere-supplying and air-purifying)
  4. Escape-only respirators (atmosphere-supplying or air-purifying). 

In most cases a Fit Test is required to reassure the proper function and use of the respirators. If you want to learn more about that, visit our Fit Testing section.

We can help in different levels such as:

  • Fit Testing
  • Hazard Assessment 
  • Mask Trade out
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