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Breathe Safe

Published: 18th Aug 2014 in OSA Magazine

The history, hierarchies and hazards associated with respiratory protection

In times of necessity, ingenuity prevails. This is certainly true of respiratory protective equipment (RPE), which has been used and developed for hundreds of years. In this article, Mark Da Silva shows that with progress in standards and technology, RPE will continue to develop and evolve for hundreds of years to come.


Respiratory protection has been used since the ancient Romans first wore animal bladders to help protect them from lead dust in mines. As far back as the First Century, Pliny the Elder is said to have described a filtering device for use against vermillion dust. Leonardo da Vinci, too, is thought to have been concerned with providing respiratory protection against chemical warfare agents and suggested using wet cloths. 

In the 16th century, Agricola described the respirator-like devices used in mines. In the United States, as in Europe in the 18th and 19th centuries, the search for respiratory protection centred on the fire services. Firemen often were required to have a full beard. They would soak their beards with water and clamp them in their teeth before going into a smoke-filled area, in an effort to block some of the larger airborne particulates.

In the 20th century, as technology improved, government regulations were enacted to protect the safety and health of workers, particularly those in high risk industries such as mining. At various points these regulations have driven innovation, which in turn has lead to the regulations’ requirements being exceeded, eventually resulting in changes to the regulations. 

At times, regulations have been the impetus for the development of increasingly advanced technologies and have created the incentive for companies to develop new, state of the art respiratory protection products. In countries that lack an effective regulatory structure, workers and citizens are taking responsibility to protect their health, occasionally using makeshift respiratory protection devices when nothing else is available (Herris, 2009).

Hierarchy of controls

Respiratory protective equipment (RPE) is a particular type of PPE used to protect the individual wearer against the inhalation of hazardous substances in the workplace air. RPE should only be used where adequate control of exposure cannot be achieved by other means, in other words, as a last resort within the hierarchy of control measures: elimination, substitution, engineering controls, administrative controls, and then PPE.

Employers are required to firstly attempt to eliminate the hazard at its source. RPE should only be used after all other reasonably practicable control measures have been taken. PPE is considered a last resort because it only protects individual workers, is prone to failure or misuse such as wearing the wrong RPE for the job, and employees wearing RPE may get a false sense of security.


Respirators are designed to prevent the inhalation of contaminated air and can be divided into two main categories: air purifying and air supplied. Air purifying respirators are designed to filter or clean contaminated air from the workplace before it is inhaled by the wearer. They are available as either disposable respirators, or as non disposable respirators with disposable filters. Air supplied respirators deliver clean, breathable air from a source independent from the wearer. Air supplied respirators are typically used for high risk environments, such as oxygen deficient atmospheres and confined spaces.

When an unknown hazard is drifting through the air the use of high quality respiratory protection is fundamental. Additionally, to select the right respiratory protection, consideration must be given firstly to the existing contaminants and the application requirements, alongside the limitations of use. When selecting RPE, ensure that the equipment meets the appropriate standard.

Additionally, the protection levels of each respirator being used must also be known. The correct selection of RPE will depend on a number of factors, including the following questions:

  • What are the airborne contaminants?
  • What is the concentration of the airborne contaminant?
  • What is the task or process being undertaken?
  • Is the employee able to wear the RPE?

In many cases, consultation with manufacturers, importers and suppliers of chemicals, including reference to the safety data sheet (SDS) of the chemical used, as well as manufacturers and suppliers of RPE, may provide suitable information on the correct type of respiratory protection required. Some RPE manufacturers and suppliers have selection charts available that can assist in identifying the appropriate respirators and filters for particular contaminants.

Documents such as codes of practice, industry standards and guides may also be able to provide information on selecting respiratory protection.

Where there is doubt, atmospheric monitoring may be needed to determine the correct RPE to use. As there are many different types of respirators available, atmospheric monitoring may assist in making an informed decision when selecting the appropriate level of respiratory protection for a given work activity.

RPE is typically needed for the following activities:

  • Irregular or short duration operations, such as inspections and maintenance
  • Jobs where the location continually changes and so fixed engineering controls are not appropriate
  • Where engineering controls have been installed, but do not reduce the concentration of air contamination to safe levels
  • Entry into confined space

PPE is the least effective means of controlling exposure to harmful substances. While RPE may be used as an immediate control measure, as mentioned previously employers must try to eliminate or minimise airborne contamination in the workplace at its source. Where this is not possible or practicable, other control methods should be put in place, such as:

Substitution - Can a less harmful substance be used, or can the substance be used in a less harmful form, such as pellets instead of powder?

  • Isolation - Can the process be isolated from the operator?
  • Engineering controls - Can ventilation be installed or plant and machinery be modified to capture contaminants?
  • Administrative controls - Can the time spent on the task be reduced?

When these control measures have been tried and RPE is still needed, a respirator suitable for the situation can be used in conjunction with the other controls. The wearing of RPE, however, should never be considered as an easy fix or long term solution for controlling exposure to airborne contaminants in the workplace.

The quandary, when it comes to using RPE, is that some workers rely on using their sense of smell as an indicator to determine when to change the filter on the respirator. 

This practice is not encouraged because:

  • Some gases do not have an odour and cannot be detected
  • Some people are unable to detect contaminants by smell
  • The contaminant may be hazardous at a low concentration and the worker may already be exposed to harmful levels by the time they smell something

Other disadvantages of RPE:

  • When RPE is in place as a long term control measure it can create an ongoing administrative and financial burden for the employer, especially when many people are required to wear RPE
  • RPE is often uncomfortable to wear, especially during warm weather
  • Wearing RPE may adversely affect the performance of the task being undertaken; e.g. it may limit vision and mobility and increase the breathing load on the individual
  • Ongoing supervision is required to ensure the equipment is being worn correctly
  • Regular maintenance is required, for example, storage, cleaning, inspection, and replacing filters

Information should always be requested from the supplier to confirm that, where applicable, the RPE purchased has been tested as a complete system and meets the appropriate standards. Do not modify any component of the RPE without the knowledge and consent of the manufacturer, as the equipment’s safety specifications may become void.

Respiratory hazards

The respiratory system is constantly working to cleanse and purify the air. Some occupational activities and environments require the extra protection of equipment specifically designed to protect against hazards that may enter the body through the nose and mouth when breathing. Many airborne hazards are invisible and odourless, and to the unsuspecting worker, the air may seem clean and free from dangers. 

Respiratory hazards include dusts, fumes, mists, gases, vapours, and oxygen deficient atmospheres.

To understand why respiratory protection is so important, the characteristics of each hazard are outlined in the following sections.

Dusts, fumes and mists 

Dusts, fumes and mists are tiny particles that are suspended in the air. Dusts are formed when solid materials are broken down in activities such as sanding, grinding and crushing. 

Fumes occur when metal is melted, vapourised, then quickly cooled, creating very fine particles that drift in the air. Welding and furnace work are likely to produce fumes. 

Mists are tiny liquid droplets usually created by spraying, mixing or cleaning activities. Mists may hold a combination of several hazardous ingredients. 

When hazardous dusts, fumes, or mists are inhaled they become trapped in the respiratory system, causing irritation, short or long term health problems - even death.

Gases and vapours 

Gases and vapours are invisible contaminants mixed in the air. Gases are substances that become airborne at room temperature. They are often produced by chemical processes and high heat operations. Gases drift quickly, rapidly become untracable to their source. 

Vapours are formed when liquids or solids evaporate, typically occurring with solvents, paints or refining activities. As with dusts, fumes and mists, breathing in hazardous gases or vapours irritates the respiratory system, causing short or long term health problems or even death.

Oxygen deficiency 

Oxygen deficiency is a lack of oxygen in the air. It can be caused by chemical reactions, fire, or displacement by other gases. In confined spaces, where ventilation is very limited or non existent, aerobic bacterial growth and oxidation of rusting metals can also cause an oxygen deficient atmosphere. Oxygen comprises only a small percentage, about 21%, of the air we breathe, yet when levels of oxygen fall below even 19.5% life threatening health problems begin to occur very quickly. 

Oxygen deficiency is a very serious situation, which can cause loss of consciousness or death in minutes.

Respiratory protection programme 

An important aspect of respiratory protection is user acceptance. As such, before issuing RPE plans must be made to ensure its use. These would include speaking to various RPE suppliers, obtaining different samples of respirators and consulting with employees. Employers must allow wearers of RPE to select a respirator that is comfortable to wear while also providing the best fit and protection.

Once the correct RPE has been selected, the next step is to implement a respiratory protection programme to ensure that RPE is being correctly worn and maintained. 

The following sections outline the main elements that a respiratory protection programme may include:

Ensuring the worker is able to wear RPE:

  • Male employees who have facial hair may not be able to achieve a proper face seal when wearing a respirator
  • Medical checks should be undertaken to ensure that the employee is physiologically and psychologically suited to wear RPE. Medical checks should screen for conditions such as respiratory and heart diseases, as well as claustrophobia

Providing cleaning and storage facilities:

  • Filters, such as those for organic vapours, must be kept in airtight containers when not in use to maximise the life of the filter
  • Refer to the manufacturer’s instructions on the correct method for cleaning and storing respirators

Inspecting RPE regularly for defects:

  • Replacement parts should be readily available; e.g. valves, straps and filters
  • Compressors used for air supplied respirators should be checked regularly to ensure that the breathing air reaching the wearer is of a suitable quality


  • Employees will need training on the need for, correct use of and maintenance of equipment. In particular, employees should be able to demonstrate that they can put on a respirator correctly and check for leaks, known as a fit check

Keeping records of maintenance:

  • The detail of record keeping required will vary depending on the RPE used and its purpose. It can range from keeping detailed logbooks of equipment to simply writing dates on filters when they are opened. Records would not normally need to be kept for disposable respirators

In some countries there are legislative compliance requirements, to which organisations must officially adhere when choosing the RPE. Employers must provide and maintain, as far as reasonably practicable, a working environment that is safe and without risks to health. The act also specifies duties applying to employees, contractors and their employees.

Employees must cooperate with the employer where actions have been taken to comply with any legislative health and safety requirements. Work health and safety regulations, such as those for confined spaces, asbestos, lead and hazardous substances, also set out the requirements on how an employer must apply the risk control processes before PPE is used.

Future frontiers

Some developing countries do not have standards in place for respirator performance or use. Through increasing awareness of occupational health and safety issues among employers, workers and governments, however, respirator regulations will be strengthened and adopted. 

The International Organization for Standardization (ISO) currently is developing global respirator performance standards that will be available for all countries to incorporate into their respirator use regulations.

These new performance standards may again pose a challenge to respirator manufacturers and may drive the development of new technologies. In addition, as the population of respirator users expands, respiratory product developers will need to consider designing respirators for an even wider variety of faces.

Elimination is considered the number one risk control to be put into practice to mitigate potential hazards. Due to the cost of implementation, however, this is not always reasonably practicable. Organisations may choose respiratory protection due to its quick and easy fix, but this resolution is much like putting a bandaid on a bullet wound - it will not address the real problems. Practical solutions need to be considered where workers are at risk.

With workplace health and safety professionals working together with agencies such as the National Institute for Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and international organisations such as the ISO, respiratory protective devices will continue to promote the development of new technologies, designs and regulations, to help protect workers around the world. As after all, necessity is the mother of invention. 


Health and Safety Authority Ireland, 2014. Accessed on 02/07/2014: www.hsa.ie/eng/Topics/Personal_Protective_Equipment_-_PPE/Respiratory_Protective_Equipment/

WorkSafe Victoria, 2005. Accessed on 02/07/2014: www.vwa.vic.gov.au/forms-and-publications/forms-and-publications/respiratory-protective-devices 

EHS Today - Herris, 2009. Accessed on 02/07/2014: http://ehstoday.com/ppe/respirators/regulation_innovation_shaped
ISO 16900-1 - Respiratory protective devices. Methods of test and test equipment Part 1: Determination of inward leakage 60.0013.340.30ISO 16900-2:2009.

Respiratory protective devices. Methods of test and test equipment Part 2: Determination of breathing resistance 60.6013.340.30ISO 16900-3:2012.

Respiratory protective devices. Methods of test and test equipment Part 3: Determination of particle filter penetration 60.6013.340.30ISO 16900-4:2011.

Respiratory protective devices. Methods of test and test equipment Part 4: Determination of gas filter capacity and migration, desorption and carbon monoxide dynamic testing 60.6013.340.30ISO/CD 16900-5.

Respiratory protective devices. Methods of test and test equipment Part 5: Breathing machine/metabolic simulator/RPD headforms/torso, tools and transfer standards 30.6013.340.30ISO/DIS 16900-6.

Respiratory protective devices. Methods of test and test equipment Part 6: 

Mechanical resistance/strength of components and connections 40.2013.340.30ISO/DIS 16900-7.

Respiratory protective devices. Methods of test and test equipment Part 7: 

Practical performance test methods 40.2013.340.30ISO/DIS 16900-8.

Respiratory protective devices. Methods of test and test equipment Part 8: Measurement of RPD air flow rates of assisted filtering RPD 40.6013.340.30ISO/DIS 16900-9.2.

Respiratory protective devices. Methods of test and test equipment Part 9: Determination of carbon dioxide content of the inhaled air 40.6013.340.30ISO/DIS 16900-10.

Respiratory protective devices. Methods of test and test equipment Part 10: Resistance to ignition, flame, radiant heat and heat 40.2013.340.30ISO 16900-11:2013.

Respiratory protective devices. Methods of test and test equipment Part 11: Determination of field of vision 60.6013.340.30ISO/FDIS 16900-12.

Respiratory protective devices. Methods of test and test equipment Part 12: Determination of volume-averaged work of breathing and peak respiratory pressures 50.2013.340.30ISO/DIS 16900-13.

Respiratory protective devices. Methods of test and test equipment Part 13: RPD using regenerated breathable gas and special application mining escape RPD: Consolidated test for gas concentration, temperature, humidity, work of breathing, breathing resistance, elastance and duration 40.2013.340.30ISO/DIS 16900-14.

Respiratory protective devices. Methods of test and test equipment Part 14: Measurement of sound level 40.2013.340.30ISO 16972:2010.

Respiratory protective devices. 

Terms, definitions, graphical symbols and units of measurement 60.6013.340.30ISO/DTS 16973.

Respiratory protective devices. Classification 30.9913.340.30ISO/TS 16974:2011.

Respiratory protective devices. Marking and information supplied by the manufacturer 90.2013.340.30ISO/DIS 16975-1.

Respiratory protective devices. Selection, use and maintenance Part 1: Establishing and implementing a respiratory protective device programme 40.2013.340.30ISO/DTS 16975-2.

Respiratory protective devices Part 2: Guidance for selection, use and maintenance 30.6013.340.30ISO/CD 16975-3.

Respiratory protective devices Part 3: Selection, use and maintenance - Fit testing procedures 30.6013.340.30ISO/TS 16976-1:2007.

Respiratory protective devices. Human factors Part 1: Metabolic rates and respiratory flow rates 90.6013.340.30ISO/TS 16976-2:2010.

Respiratory protective devices. Human factors Part 2: Anthropometrics 90.6013.340.30ISO/TS 16976-2:2010/Cor 1:2011 and 60.6013.340.30ISO/TS 16976-3:2011.

Respiratory protective devices. Human factors Part 3: Physiological responses and limitations of oxygen and limitations of carbon dioxide in the breathing environment 60.6013.340.30ISO/TS 16976-4:2012.

Respiratory protective devices. Human factors Part 4: Work of breathing and breathing resistance: Physiologically based limits 60.6013.340.30ISO/TS 16976-5:2013.

Respiratory protective devices. Human factors Part 5: Thermal effects 60.6013.340.30ISO/TS 16976-6:2014.

Respiratory protective devices. Human factors Part 6: Psycho-physiological effects 60.6013.340.30ISO/TS 16976-7:2013.

Respiratory protective devices. Human factors Part 7: Hearing and speech 60.6013.340.30ISO/TS 16976-8:2013.

Respiratory protective devices. Human factors Part 8: Ergonomic factors 60.6013.340.30ISO/CD 17420-1.

Respiratory protective devices. Performance requirements Part 1: Supplied breathable gas devices 30.6013.340.30ISO/CD 17420-2.

Respiratory protective devices. Performance requirements Part 2: Filtering devices 30.6013.340.30ISO 17420-3:2012.

Respiratory protective devices. Performance requirements Part 3: Thread connection 60.6013.340.30

Published: 18th Aug 2014 in OSA Magazine


Mark Da Silva

Mark Da Silva is a registered safety practitioner for the Safety Institute of Australia (SIA) and has acquired the status of Chartered Fellow - the peak professional graded membership of the SIA. He has academic accreditations including a master’s degree in Applied Science (OHS-RMIT) and a graduate diploma of Occupational Hazard Management (VIOSH), with extensive industry knowledge including safety leadership, organisational behaviour, environmental sustainability and risk.

Through the completion of a master’s thesis on safety leadership, Da Silva has an exemplary understanding of workplace safety culture and behaviour based safety techniques. Case studies developed and proven in Da Silva’s thesis incorporate management commitment considerations, information and communication dimensions, plus workplace perception.

Da Silva has applied his theoretical framework to his professional conduct through the development and implementation of effective safety cultural surveys, which were paramount in many organisations’ cultural step changes, essentially adding value to the safety improvement and action plans for clients.

As a proactive, conscientious and adaptable health, safety and environment professional, Da Silva’s personal aphorism is “Go Home Safe!”

Skilled in developing, implementing and executing key strategic business improvement initiatives, Da Silva draws on wide ranging practical experience, including heavy industrial manufacturing, telecommunications, oil and gas and renewable energy resources, infrastructure operations and the maintenance and construction of major projects, with knowledge attained through academic accreditation.

Mark Da Silva



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