Protecting our lungs with respiratory protection

Our lungs have evolved over thousands of years to deal with naturally occurring levels of particles — dusts, pollens, small pieces of vegetation, seeds, etc. We have developed certain protective mechanisms such as nasal hairs, mucous-lined airways and even coughing and sneezing as ways to control exposures to reduce the chance they cause significant damage to our respiratory system. But this protection can only go so far. Modern industrial processes can expose us to a myriad of substances that do not occur naturally and we have little or no effective defence against many of these without PPE.

We breathe in about 8–10,000 L of air per day when just sitting quietly. Working hard physically increases this amount significantly. Each of these litres of air may contain a level of a substance that can enter the lungs and damage its structure directly or be absorbed into the bloodstream and cause health effects in other parts of the body. Effects can range from simple irritation right through to permanent incapacity or lethal outcomes such as lung cancer. The time frame for these effects can be immediate (eg, a whiff of strong ammonia will cause an immediate response) or long term (some exposures can take years for the health outcomes to appear eg, coal dust and asbestos).

Airborne contaminants we can inhale come in two broad categories — particles and gases/vapours.

Particles come in a wide range of materials (eg, dust, pollens, welding fume, asbestos fibres and paint spray) and sizes. Some will stay suspended for many hours long after they have been released into the air. Our lungs have some protective mechanisms to capture particles we inhale, but these are not able to deal with large exposures that can occur in workplaces.

Gases and vapours are more insidious. Our lungs are designed to inhale air (a mixture of gases) deep into the lungs so that oxygen can be absorbed into the bloodstream. Unlike particles, our lungs do not have any effective filtering system to capture gases and vapours, so these can travel deep into our lungs and may then get absorbed into our blood.

Health effects from overexposure to these airborne contaminants can vary from short-term effects like stuffy nose, sore throat, headache, coughing, nausea and irritation to longer-term health issues such as lung damage with reduced lung function, fertility, emphysema, neurological effects, heart damage and cancer.

Protection in the workplace

A Respiratory Protection Program run according to the guidance in AS/NZS1715 is needed for workers to achieve a safe, reliable and ongoing level of protection from airborne contaminants in Australian workplaces.

The laws of the states and the Commonwealth mandate the use of appropriate strategies to provide a safe workplace. Employers are required to use appropriate means to prevent health hazards to the workers. Providing respiratory protection for workers is part of the duty of care of the employer in the modern industrial situation.

Each workplace will have its own problems and hazards and will require assessment by a suitably qualified person to determine if there is a need for respiratory protection and, if so, what specific types of respirators are needed.

Ideally, there will be controls that keep these airborne contaminants to a minimum, eg, using materials that do not create a respiratory hazard, use of extract ventilation, use of sealed delivery and mixing systems, etc. However, there will be circumstances where personal respiratory protection is needed. The challenge is to wear the right respirator to make sure we protect ourselves from these hazards. By wearing a well-fitted respirator 100% of the time exposed, you can greatly reduce your health risks, both short and long term.

Respirators are designed to reduce and control exposures to substances, aiming to protect to levels that should not be hazardous to most wearers.

The basis for selection and performance of respirators in Australia is normally based on a number of documents, with the relevant Australian Standards being paramount. These are:

• AS/NZS1715 “Selection, use and maintenance of respiratory protective devices” provides users with the information they need to use appropriate respiratory protection systems. It gives them guidance on the selection factors and types of respirators available, their performance and their applications.
• AS/NZS1716 “Respiratory protective devices” is the performance standard. It sets out the performance parameters and requirements for the different types of respirators. State OHS regulators, eg, Safework NSW, Worksafe Victoria, etc, normally expect respirators used in Australian workplaces to meet the requirements of this standard.

There are other relevant state and federal regulations and codes of practice that specify the appropriate level of respiratory protection to be used for certain tasks eg, for use when removing asbestos or when spraying two-pack paints containing isocyanates.

Assessing the hazard

There are a number of basic requirements needed to assess a respiratory hazard. The first is to identify the contaminant, and then to quantify the amounts of the airborne contaminant in the working environment. In some cases, this may require the use of an occupational hygienist or safety professional, who will have the knowledge and resources to determine the airborne concentrations of the materials in question, and to make informed recommendations as to the appropriate responses to the hazard.

Specific high-risk respiratory hazards such as working in confined spaces or Hazmat response will require specialised equipment and assessment of the circumstances. This should be done by a suitably qualified occupational hygienist or safety professional.

After identifying the type and size of the respiratory hazard, suitable respiratory equipment for these conditions should be identified. Normally there will be a number of options, depending on the local conditions, wear time, cost and other factors, that will help to decide the appropriate equipment. Advice from manufacturers of respiratory equipment can assist in determination of the suitability and limitations of respiratory equipment.

Providing the equipment

The most widely used respirator type is the air purifying respirator — this uses one or more filters to remove contaminants from the inhaled air. These are powered by the wearer’s own breathing cycle. Included in this category are maintenance-free or disposable type respirators as well as re-usable type respirators in both half face (covering the mouth and nose only) and full face respirator (covering the whole face and eyes) designs. According to the contaminant, a particulate filter is needed to capture particles and/or a specific gas filter is needed for various classes of gases or vapours like ammonia or acid gases or solvent vapours, etc. The user must determine the correct type of filter and respirator to protect him/her from the specific type and quantity of the airborne contaminants present in his/her workplace.

Getting the right fit

An issue of critical importance for any face fitting respirators is facial fit. There are many reasons why a respirator may not fit on a specific worker’s face — facial contours, facial hair, heat, strenuous work and makeup on the face. Those with large moustaches, beards or even stubble will not be able to get an effective seal between the face and the respirator, and inhaled breath can then bypass the filter, not go through it, so they can have little or no respiratory protection. The individual wearer should be fit tested with the mask to prove it does (or does not) fit their face. This is a specified process that is required by AS/NZS 1715 and the relevant OHS regulators. There is fit testing equipment available as well as consultants who can do this testing for you.

There are several reasons why a half or full face mask may not be acceptable to an individual:

• Facial hair — the wearer has a beard of other interfering facial hair and wants to keep it.
• There is no tight-fitting mask that fits and is acceptable to the wearer.
• The potential wearer has some physical condition that is not compatible with the increased breathing resistance caused by a filtering mask eg, they have a lung issue and breathing problems and do not need an increase in breathing resistance from a respirator.
• There is a reluctance by the individual to wear a mask — eg, claustrophobia, heat issues or compatibility with other PPE.

For those individuals who cannot or will not wear a tight-fitting mask, use of a battery powered air purifying respirator (PAPR) or supplied airline respirator system, fitted with a suitable headtop like a hood or helmet can provide an alternative that can give the required protection.

A PAPR has the following benefits:

• No breathing resistance.
• Powered air delivery creates a moving flow which creates a cooling effect.
• Can be used with facial hair that does not interfere with the faceseal of the headtop.
• The headtop selected can provide multilevel protection — can include head, eye/face and/or welding protection as well as respiratory protection.

A supplied airline respirator has all of the benefits above plus:

• Does not require a filter that is suitable for all of the airborne contaminants present in the workplace air.
• High protection levels according to AS/NZS1715.
• Can use vortex heaters or coolers to ‘air condition’ the air coming into the headtop by ±250°C.

There can be specific circumstances where suitable filters are not available for the contaminants and an airline respirator supplying clean filtered air to a suitable headtop from a distant source can be suitable.

Maintaining the equipment

All workers using respirators should be trained in routine maintenance and storage. Disposable types are discarded when clogged, damaged or unacceptably dirty. Other respirator types are re-usable but will need regular inspection, cleaning and replacement of worn or faulty parts as required to get the expected performance and protection.

All filters have a service life — they don’t last forever. Gas filters will gradually fill up with contaminants and then will no longer absorb. At this point the gas/vapour contaminant will break through the filter into the lungs. These filters need to be changed before they are full. Exactly when this needs to happen will depend on the specific circumstances — type of gas/vapours, amounts, humidity levels, filter size and type, breathing rate, etc.

Particle filters will load with the contaminant at some rate over time and thus will become harder and harder to breathe through. This restriction to breathing will eventually become too much and the particle filter should be changed. All types of filters should be changed on a regular basis according to the manufacturer’s instructions and in accordance with the levels of contaminants in the workplace.

The future

An ISO Standard for Respiratory Protection is currently in development that will change the framework for design and selection of respiratory protective equipment, although this is still a number of years away. Advances in materials technology and electronics will also impact on future product designs.