Breathe Easy

Respiratory Protection Equipment (RPE) is a particular type of Personal Protection Equipment (PPE), used to protect the individual wearer against the inhalation of hazardous substances or other agents in air particulate forms in the workplace environment.

In order to understand and assess the potential hazardous substances or other agents in air particulate forms, which the workers are exposed to, a comprehensive and contextualised hazard identification, evaluation and control must be in place, which is beneficial in selecting the suitable type of respiratory protective equipment for the specific scope of work.

The most important route by which toxic chemicals enter our bodies is through inhalation. The best way to protect workers from inhaling such chemicals is to reduce or prevent contamination of the air they breathe through control measures such as elimination or substitution of toxic chemicals, installation of enclosures and implementation of engineering controls such as local exhaust ventilation systems. Where such measures are not feasible or cannot be implemented immediately or are inadequate to control the hazard, then supplementation with personal protective equipment such as respiratory protection would be necessary. Respiratory protection may also have to be used in maintenance operations or during emergencies.

Indications for respirator usage

There are two main indications for when appropriate RPE would be needed. They are:

• When exposed to hazardous air contaminants in concentrations which exceed the permissible exposure limits
• When in an oxygen deficient environment (< 19%), e.g. in a confined space such as a storage tank or manhole

Effective respiratory protection

If respirators are used, they should be used properly so as to ensure effective protection. Otherwise they can give a false sense of security and in fact be a danger to the user. For respirators to be effective, they must:

• Be of the correct type for the situation or hazard
• Fit the persons using them
• Be worn 100% of the time when in the hazardous environment
• Be properly maintained in good working condition

Correct type of respirator

There is no one-fit, all-purpose respirator. It is very important to select the correct type of respirator for the particular hazard or situation. Information on the type of respirator could be found in the Safety Data Sheet or could be provided by the respirator supplier. Ultimately, there are two types of respirators: air-supplied and air-purifying.

Air-supplied

Air-supplied respirators provide a separate supply of air, e.g. air-line respirators and self-contained breathing apparatus (SCBA). These respirators must be used when in an oxygen deficient environment or when the levels of the contaminants are at very high concentrations beyond the protective limits of most air-purifying respirators. Examples of such situations are maintenance operations or emergencies, e.g. firefighting, rescue and accidental leakage.

Air-purifying

Air-purifying respirators work by filtering or absorbing air contaminants as they pass through the respirator filter or cartridge. There are filters for particulates, e.g. dust, mist and fume and cartridges for vapours and gases. Some of the cartridges are specific for certain types of gases or vapours. Sometimes, a combination of a toxic dust filter and an organic solvent cartridge is required, e.g. a worker exposed to both pesticide dust and solvent vapour.

The respirators also come with various types of face pieces, e.g. full-face mask or half mask. Full-face respirators have the advantage of eye protection and a higher protection level but are heavier and bulkier. There are also disposable respirators which have the advantage of being lighter and being maintenance free. However, these may not be available in different sizes. In the United States (U.S.) and Europe, the different types of face masks are usually labelled in the following manner – “letter number”.

The three letters used are N, R and P which stand for “not oil resistant”, “oil resistant” and “oil proof” respectively. The number that follows indicates the percentage of airborne particles filtered by the mask. In Europe, masks are categorised into class 1, 2 and 3.

Not oil resistant

N95 – Filters >95% of airborne particles

N99 – Filters >99% of airborne particles

N100 – Filters >99.97% of airborne particles

Oil resistant

R95 – Filters >95% of airborne particles

R99 – Filters >99% of airborne particles

R100 – Filters >99.97% of airborne particles

Oil proof

P95 – Filters >95% of airborne particles

P99 – Filters >99% of airborne particles

P100 – Filters >99.97% of airborne particles

European nomenclature for “filtering face pieces” (FFP also called “filtering half masks”)

FFP1 – Filters >80% of airborne particles

FFP2 – Filters >94% of airborne particles

FFP3 – Filters >99% of airborne particles

European nomenclature for the classes of particle filters that can be attached to a face mask

P1 – Filters >80% of airborne particles

P2 – Filters >94% of airborne particles

P3 – Filters >99.5% of airborne particles

Consistent usage

The protection factor is reduced each time the respirator is removed in the presence of contaminated air. Respirators should be worn all the time while in a contaminated environment, i.e. worn before entry to the environment and removed only when outside the environment. Workers should not remove the respirators when conversing with other workers.

“there is no one-fit, all-purpose respirator”

Hazard identification

Identification of hazard is the first and most critical steps which is undertaken in the Risk Management process. Damage caused by inhaled particles is dependent on their physical, chemical and biological properties as well as the concentration, size, shape and density. This process requires knowledge of the following:

• Work Processes
• Nature of Exposures
• Nature of substances used and their risks
• Intermediates or products formed
• Potential for oxygen-deficient atmosphere

When conducting hazard identification, the hazard associated with each of these work processes are identified with their potential outcomes in terms of probability and consequences (incidents or accidents). Safety Data Sheets are obtained from the manufacturer or supplier to aid in identifying the hazardous components (inclusive of intermediate products).

Engagement interviews and worksite inspection are recommended, so as to further understand the potential respiratory risks involved. For example, when working in confined space, the potential oxygen-deficient atmospheres developing before entry and during work inside the confined space must be carefully considered, and suitable risk control measures carried out to address and mitigate such risk.

Hazard Evaluation

Qualitative and quantitative information is required to enable clear assessment of the atmospheric conditions in the workplace and measurement of the contaminants varies with the type of hazard present.

Radiation Hazard

A survey to aid in determining the radionuclide(s) being present, the magnitude of possible doses and physical forms of radiation sources should be carried out. Each employee of a licensed radiation vendor shall wear prescribed monitoring equipment and device as stipulated in the Radiation Protection Act to determine the level of exposure of the employee.

Chemical Hazard

The level of exposure of users to inhalable hazards shall be determined by a competent person measuring the concentration of air contaminants or oxygen using appropriate sampling instruments and analytical methodologies. Assessments need to be conducted for every level of oxygen, flammables, and toxic airborne contaminants prior to any entry into confined space for work. The size of particles such as dust, mists, fumes or fibres affect the site of depositions within the respiratory system. Hence particle size shall be determined with size selective sampling.

Large particles with an aerodynamic equivalent diameter up to 100 millimicron (mµ) in size are referred to as inhalable and inspirable particles. Small particles < 10 millimicron (mµ) in size indicate that they are respirable particles, which are able to penetrate deep into the lungs. Respirable particles are particularly important when considering the suitability of respiratory protection equipment. The need for respiratory protection against ultra-fine particles with aerodynamic equivalent diameter of less than 100 nanometres in size has not been established, however, respiratory protection equipment used could reduce the risk of exposure.

Appropriate sampling strategies shall be utilised to determine the full shift Time-Weighted Average (TWA) concentration and the short-term concentration (if needed and when necessary) of the inhalable hazard to users which may be exposed. The result shall be compared with the permissible exposure levels in the legal requirements or any other comparable standards.

Biological Hazards

Microorganisms encountered in the workplace may be classified by the following risk group (in accordance with AS / NZS 1715:2009):

• Risk Group 1 -(low individual and community risk) – a microorganism that is unlikely to cause human disease
• Risk Group 2 – (moderate individual risk, limited community risk) – a pathogen that could cause human disease and which might be a hazard in occupational environments but is unlikely to spread in the community
• Risk Group 3 – (high individual risk, limited community risk) – a pathogen that can cause severe human disease and may be a serious hazard in occupational environments. It could present a risk if it spreads to the community, but there are usually effective preventative or treatment measures available
• Risk Group 4 – (high individual and community risk) – a pathogen that usually produce life-threatening human disease, and is a serious hazard in the occupational environments; readily transmissible into the community and the effective preventative or treatment measures are not available

There was no defined occupational exposure limit for microorganisms. This is due to the rationale of the infectious inhalation doses, and the air concentration of infectious particles to which the users may be exposed, are usually uncertain. One of the most helpful tools available for performing a microbiological risk assessment is the listing of risk groups for microbiological agents. However, simple reference to the risk grouping for a particular agent is insufficient in the conduct of a risk assessment. Other factors that should be considered are:

• Pathogenicity of the agent and infectious dose
• Potential outcome of exposure
• Natural route of infection
• Other routes of infection, resulting from manipulation (parenteral, airborne, ingestion)
• Stability of the agent in the environment
• Concentration of the agent and the volume of concentrated material to be manipulated
• Work activity planned (sonication, aerosolisation, centrifugation)
• Any genetic manipulation of the organism which may extend the host range of the agent’s sensitivity to known, effective treatment regimens
• Local availability of effective prophylaxis or therapeutics interventions

Respiratory protection programme

Companies which require their workers to use respirators should implement a self-regulatory and comprehensive respiratory protection programme. This should include the following:

• Regular environmental monitoring of the hazard
• Engineering control to reduce the hazard where practicable
• Selection and provision of suitable respirators
• Supervision to ensure proper fit and consistent usage
• Proper maintenance of respirators
• Training in use and care of respirators
• Medical examinations for fitness to use respirators

Responsible persons

The respiratory protection programme shall be established by the occupier, employer or principal, and also a designated person to administer the programme. The individual designated shall have knowledge and competence in understand the airborne contaminants and its effects, in the workplace. They shall overall control of the implementation of the respiratory protection programme. Resources shall be sufficiently provided by the occupier, employer or principal, to ensure smooth and sustainable implementation.

Limitation of respirators

Many factors need to be considered when selecting a suitable respirator for a particular situation. It is important to ensure that only the correct type of respiratory protective devices were being used, and where there is any doubt, expert advice should be sought. Selection consideration could be on:

• Hazard-related factors
• Task-related factors
• Accessories-related factors
• Operator-related factors

Fitness for use

Most workers should have no problems breathing through the respirators and working. A few workers with poor cardiovascular function may have difficulty breathing through the respirators. Workers with poor effort tolerance or unstable angina may have difficulty doing strenuous exercise and carrying the heavy air-supplied respirators. Where indicated, lung function tests and stress electrocardiogram (ECG) can be carried out.

Respirator fit testing

There must be a good seal between the edges of the respirator and your face. Otherwise, the air contaminants would leak in through the edges of the respirator. The following may contribute to poor fit:

• Wrong size of respirator
• Wrong method of wearing respirator, e.g. using single strap only
• Wrong positioning of facepiece or straps
• Straps too loose
• Facial hair including beards
• Use of handkerchief or towel under the respirator
• Facial deformities
• Defective respirator

The following can be conducted to ensure a proper fit:

• Select the correct size/type of respirator
• Put on the respirator according to the manufacturer’s instructions, adjusting the straps and face piece to obtain the best fit
• Carry out a fit test at time of issue of respirator:
  • This is based on the ability to taste an aerosol of a substance like saccharin with the respirator worn
  • With a proper fit, you should not be able to taste it
• Carry out user seal checks each time the respirator is used:
  • With the respirator worn, cover the filter or cartridge with the palm of your hands
  • Breathe in and hold your breath
  • If there is no obvious leak, the face piece should collapse slightly and remain so

Maintenance inspection and storage

The cartridges or filters of non-disposable respirators must be regularly changed to ensure continued protection. Particulate filters should be changed once they are clogged up resulting in increased breathing resistance. Gas and vapour cartridges must be changed once they are saturated and can no longer absorb any more of the contaminant. This would be indicated by a “breakthrough” of the chemical into the respirator, e.g. smell or irritation by the chemical. The higher the concentration, the more frequent the change.

Once there is a breakthrough of the contaminant, the worker must leave the area and change the cartridge immediately. There must be good warning properties of the contaminant in order for a breakthrough to be detected. Otherwise, the air-supplied respirators must indicate this clearly.

“employers shall ensure that all respirator users are trained by the equipment manufacturer”

User training

Employers shall ensure that all respirator users are trained by the equipment manufacturer/supplier before any commencement of use. Such training could ensure that users are familiar with the right fitting, pre-use inspection protocols and maintenance after use, and the regular replacement of filters or filtration cartridges.

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References

1. AS/NZS 1715 : 2009 Selection, use and maintenance of respiratory protective equipment
2. AS/NZS 2243.3 : 2002 Safety in laboratories – Part 3 : Microbiological aspects and containment facilities
3. BS EN 529 : 2005 Respiratory protective devices – Recommendations for selection, use, care and maintenance
4. Biological Agents and Toxins Act 2005
5. OSHA 1910.134 on Respiratory Protection
6. Practical Radiation Technical Manual, Personal Protective Equipment International Atomic Energy Agency 2004
7. Radiation Protection Act 2008
8. The Workplace Safety and Health Act (Chapter 354A) 2006
9. The Workplace Safety and Health (General Provisions) Regulations 2006
10. WHO Laboratory Biosafety Manual Third Ed 2004