Guidance on the use of respiratory and facial protection equipment.

Infectious micro-organisms may be transmitted by a variety of routes, and some may be spread by more than one route. Respiratory and facial protection is required for those organisms that are usually transmitted via the droplet/airborne route, or when airborne particles have been artificially created, such as during 'aerosol-generating procedures'. A range of personal protective equipment that provides different degrees of facial and respiratory protection is available. It is apparent from the recent experiences with severe acute respiratory syndrome and pandemic (H1N1) 2009 influenza that healthcare workers may have difficulty in choosing the correct type of facial and respiratory protection in any given clinical situation. To address this issue, the Scientific Development Committee of the Healthcare Infection Society established a short-life working group to develop guidance. The guidance is based upon a review of the literature, which is published separately, and expert consensus.

Key points

Healthcare workers (HCWs) may have difficulty in deciding whether facial and respiratory protection is required, and in choosing which combination is appropriate in any given clinical situation. This document provides guidance to support HCWs to select appropriate respiratory and facial protection.

Respiratory and facial protection as considered in this guidance is required to deal with the presence of potentially infectious particles in the air.

A range of personal protective equipment (PPE) that provides facial and respiratory protection is available. In most clinical scenarios where this is required, it will comprise either a surgical mask or a respirator, with or without eye protection.

The requirement to wear respiratory and facial protection will be determined by a range of factors that involve a risk-assessment-based approach related to: the procedure/task to be undertaken; known/suspected infection; and presenting patient symptoms.

The selection and use of respiratory and facial protection equipment must be underpinned by appropriate staff education and training.

Specific recommendations on selection of equipment based upon this approach are presented in detail within the main body of the document.

In the majority of situations where respiratory and facial protection is required, a surgical mask will be adequate. For a very small number of pathogens that are truly transmissible via the airborne route, or where aerosol-generating procedures (AGPs) involving infectious body fluids are being undertaken, a respirator will be required. The requirement for eye protection will largely be determined by the risk of splashing/spraying of blood and/or body fluids to the eyes/face.

Recommendations for future research to address outstanding evidence gaps are provided.

Introduction

A range of PPE that provides different degrees of facial and respiratory protection is available. This includes surgical face masks, respiratory protection equipment (RPE), protective spectacles, goggles and visors. It is apparent from recent experiences with severe acute respiratory syndrome and pandemic (H1N1) 2009 influenza that HCWs may have difficulty in choosing the correct type of facial and respiratory protection in any given clinical situation.1, 2

To address this issue, the Scientific Development Committee of the Healthcare Infection Society established a short-life working group in May 2011 to develop appropriate guidance. The working group included representation from the Healthcare Infection Society, Public Health England, Health and Safety Executive (HSE), Association of National Health Occupational Physicians, Health Protection Scotland, Infection Prevention Society, Intensive Care Society, Clinical Virology Network and British Infection Association. The guidance is based upon a review of the literature (which can be accessed separately) and expert consensus. Although the guidance also takes account of relevant current UK health and safety legislation, the majority of the material will be more widely relevant.

Implementation of this guidance is a matter for local determination based on risk assessment and the need to adhere to any relevant health and safety legislation. Employers in the UK have a duty of care to their employees to provide a safe working environment, which may include the provision and use of PPE (see Appendix 3).

Aim

This article provides guidance (best practice guidelines) to support HCWs in hospital or community settings to select and wear the appropriate respiratory and facial protection to minimize the risk of acquisition of infection in the workplace.

Exclusions

This guidance does not cover the use of powered respirators, chemical exposures and laser plumes, or Category 4 pathogens. Recommendations on the latter are available from the Advisory Committee on Dangerous Pathogens and the HSE document ‘Respiratory protective equipment at work: a practical guide’.

Advice on the wearing of respiratory and facial protection by patients and visitors is also out with the scope of the current guidance.

Risks associated with infectious particles and routes of transmission

The respiratory and facial protection considered in this guidance is required to deal with the presence of infectious particles in the air. These particles form a continuous spectrum of sizes and resultant properties. The size of the particle determines the microbial numbers it can carry, the distance it can travel, how deeply it can penetrate the host's respiratory tract, and what form of protection will be necessary.

For convenience, particles can be grouped into functional units categorized by their routes of transmission.

Splashes: large particles (>100 μm in diameter) that fall out of airborne suspension within a few seconds.

Droplets: smaller particles but larger than aerosols (approximately 5–100 μm in diameter). While the lower range of these particle sizes (<20 μm) will remain airborne for many minutes, particles >20 μm fall out of airborne suspension within seconds. Droplet particles penetrate the respiratory tract to above the alveolar level. However, if a liquid (aqueous) droplet evaporates before falling to the ground, it can shrink to become an aerosol particle known as a ‘droplet nucleus’.

Splash and droplet transmission occurs as a result of droplets being expelled from the respiratory tract of an infected individual (e.g. during coughing and sneezing). These may impact directly on to a mucosal surface or conjunctiva of a susceptible individual. Such transmission tends to be relatively efficient (large particles can contain high numbers of microbes), but is only effective over the short distance before these particles fall out of the air.

Traditionally, a distance of 1 m6, 7, 8 has been used to define the need for droplet precautions; however, this distance is recommended as the minimum rather than an absolute distance.

Protection against splashes and droplets requires barriers to protect the eyes, nose, mouth and upper respiratory tract of those exposed.

Aerosols: very small, lightweight particles with neutral buoyant density that can remain in suspension in the air for long time periods and travel long distances. These particles can penetrate the respiratory system to the alveolar level and are generally <5 μm in diameter. Aerosol particles can be formed from the evaporation of a larger droplet particle. Aerosols formed in this way are termed ‘droplet nuclei’ but behave as all other aerosols.

Airborne transmission (literally ‘via the air’) occurs as a result of aerosol particles being generated from the respiratory tract of an infected individual during, for example, coughing and sneezing and during procedures that put sufficient energy into infectious body fluids to break them up into small enough particles to form aerosols directly or via droplet nuclei (AGPs). Such transmission tends to be relatively inefficient and requires close proximity, prolonged proximity, high levels of dispersion, high susceptibility or a combination.

Protection against aerosols requires filtration of inhaled contaminated air (i.e. the use of respirators).

AGPs can generate an aerosol hazard from an infection that may otherwise only be transmissible via splashes or droplets. The following procedures are considered to be AGPs (this is currently an area of active research and this list is likely to be subject to change to reflect this):

intubation, extubation and related procedures (e.g. manual ventilation and open suctioning);

cardiopulmonary resuscitation;

bronchoscopy;

surgery and post-mortem procedures involving high-speed devices;

some dental procedures (e.g. drilling);

non-invasive ventilation (e.g. bi-level positive airway pressure and continuous positive airway pressure ventilation);

high-frequency oscillating ventilation; and

induction of sputum.

Whilst other procedures/equipment may generate an aerosol from material other than patient secretions, they are not considered to represent a significant infectious risk. Procedures in this category include:

pressurized humidified oxygen (unless other risks exist); and

medication administered via nebulization.

Protection against aerosols requires RPE to remove (filter) aerosols from inhaled air. As aerosols are frequently generated along with droplets and splashes, barrier protection of eyes is also usually required if close to a dispersion source.

The rate of clearance of aerosols in an enclosed space (room) is dependent on the extent of ventilation: the greater the number of air changes per hour (ventilation rate), the faster any aerosols will be diluted. The time required for dilution of aerosols, and thus the time after which the room can be entered without respiratory protection, can be determined following a risk assessment. The risk assessment should take into account the number of air changes per hour (assuming perfect mixing, a single air change removes 63% of airborne contamination, and each subsequent air change removes 63% of what remains; therefore, five air changes reduces contamination to <1% of its former level, assuming dispersion has ceased).

A list of the more commonly encountered infections and their routes of transmission is given in Table I .

Table I

Commonly encountered infections and their routes of transmission

Pathogen	Disease	Immunization (refer to appropriate immunization guidance, e.g. ‘Green Book’ in UK20)	Main route of transmission	Respiratory personal protective equipment for healthcare workers
				Surgical face mask required	FFP3 required	FFP3 for AGP requireda
Bordetella pertussis	Pertussis/whooping cough	Should be vaccinated as part of childhood programme. Protective response in approximately 80%	Droplet	✓Until patient has received five days of appropriate antibiotics		✓
Chlamydia pneumoniae	Pneumonia	Not available	Droplet	✓Duration of acute symptoms until patient is no longer considered infectious		✓
Haemophilus influenzae	Epiglottitis Meningitis	Hib vaccine given as part of childhood immunization in UK20	Droplet	✓Until patient has received 24 h of appropriate antibiotics		✓
Influenza virus	Upper +/− lower respiratory tract infection	Healthcare workers should be vaccinated. Protective response in approximately 70%	Droplet, aerosol if AGP	✓Duration of respiratory symptoms, particularly cough.Prolonged shedding and detection of virus in nasopharynx of immunocompromised patients		✓Duration of respiratory symptoms, particularly cough.Prolonged shedding and detection of virus in nasopharynx of immunocompromised patients
Legionella spp.	Lower respiratory tract infection	Not available	Person-to-person transmission not considered a significant transmission route	Standard infection control precautions apply
Measles virus	Measles	Live-attenuated vaccine. Protective response in approximately 90%	Droplet/aerosol		✓b(recommended to be worn until patient is no longer considered infectious)	✓
Mumps virus	Mumps	Live-attenuated vaccine (effectiveness 64%)	Droplet	✓b(recommended to be worn until patient is no longer considered infectious)		✓
Mycobacterium tuberculosis	Smear-positive pulmonary or laryngeal disease	Healthcare workers should be vaccinated. Response rate/protection is 70–80% and <70% protection against respiratory disease	Aerosol		✓Until multi-drug-resistant or extensively-drug-resistant tuberculosis excluded by laboratory testing	✓
Mycoplasma pneumoniae	Pneumonia	Not available	Droplet	✓Duration of acute symptoms		✓
Neisseria meningitidis	Meningitis	Healthcare workers are not routinely vaccinated but may require risk assessment for prophylaxis	Droplet	✓Until patient has received 24 h of appropriate antibiotics		✓
Norovirus	Winter vomiting disease	Not available	Droplet	✓Only if spillage/risk of splashing
Rubella virus	Rubella	Live-attenuated vaccine (95–100% protection)	Droplet	✓b(recommended to be worn until patient is no longer considered infectious)		✓
SARS coronavirus	Pneumonia	Not available	Droplet/aerosol		✓(recommended to be worn until patient is no longer considered infectious)	✓
Streptococcus pneumoniae	Pneumonia, meningitis	Pneumococcal polysaccharide vaccines available for various at-risk groups, but are not routinely indicated for healthcare workers in the UK20	Droplet	✓cOnly required if evidence of ongoing transmission within a healthcare facility; if so, continue until patient has received 24 h of appropriate antibiotics		✓
Varicella zoster virus	Chickenpox	Live-attenuated vaccine. Protection is 75% (for adolescents and adults)	Droplet/aerosol		✓b(recommended to be worn until patient is no longer considered infectious)	✓
Other respiratory virusescAdenovirusRhinovirusCoronavirus (non- SARS)Parainfluenza virusRespiratory syncytial virus	Upper +/−lower respiratory tract infection	Not available (although adenovirus vaccine in production for military services)	Droplet	✓cDuration of respiratory symptoms, particularly cough.Prolonged shedding and detection of virus in nasopharynx of immunocompromised patients		✓

FFP, filtering face piece; AGP, aerosol-generating procedure; SARS, severe acute respiratory syndrome.

AGPs are defined as: intubation, extubation and related procedures (e.g. manual ventilation and open suctioning); cardiopulmonary resuscitation; bronchoscopy; surgery and post-mortem procedures in which high-speed devices are used; dental procedures; non-invasive ventilation (e.g. bi-level positive airway pressure ventilation and continuous positive airway pressure ventilation); high-frequency oscillatory ventilation; and induction of sputum. NB. These procedures are likely to change as new evidence emerges.

Maintaining immunity in the healthcare worker population helps to prevent transmission of vaccine-preventable diseases to and from healthcare workers and patients. Staff who have regular clinical contact with patients and who are directly involved in patient care should have a documented history of all immunization. NB. In relation to childhood illnesses and use of masks, no vaccine offers 100% protection and a small proportion of individuals get infected despite vaccination. Personal protective equipment should be used as a means of protecting from the risks that remain. For further information regarding selected vaccinations for healthcare workers, please refer to the Green Book.

In routine clinical practice, healthcare workers do not commonly wear masks when dealing with patients presenting with symptoms of a ‘common cold’ or ‘influenza-like illness’. However, in a patient with undiagnosed respiratory illness where coughing or sneezing are significant features, or in the context of known widespread respiratory virus activity in the community or a suspected or confirmed outbreak of a respiratory illness in a closed or semi-closed setting, the need for appropriate respiratory and facial protection to be worn should be considered as per Figure 1.

Figure 1

Flow diagram for the selection of respiratory and facial protection. FFP, filtering face piece; AGP, aerosol-generating procedure. a Airborne (aerosol) spread refers to inhaled infectious particles small enough to penetrate down to, and be retained in, the deepest part of the lungs (alveoli). These particles are <5 μm in size, too small to be seen by eye and can remain suspended in the air for prolonged periods of time. This is in contrast to droplet spread, which is associated with larger particles (>5 μm) that do not readily penetrate the lower respiratory tract, but may cause infection by impacting directly upon a mucosal surface or conjunctiva. Table I describes the transmission route for a range of pathogenic micro-organisms spread wholly or partly by airborne (aerosol) or droplet routes.

Types of respiratory and facial protection

The range of different types of respiratory protection and other components of facial protection that are available for routine use by HCWs are described below (the key attributes of surgical masks compared with RPE are summarized in Table II ).

Table II

Comparison of attributes of surgical masks compared with respiratory protection equipment

	Surgical mask	Respirator (e.g. FFP3)	Powered respirator
Cost	Inexpensive (depends on type)	Moderately expensive (depends on type)	Expensive
Level of protection	Protects mouth, nose and respiratory tract against splashes and droplets (but not aerosols)	Protects mouth, nose and lower respiratory tract against splashes, droplets and aerosols	Protects mouth, nose and lower respiratory tract against splashes, droplets and aerosols
Fit testing requirement	Not required	Required	Not required
Eye protection	May be included	Not included	Included
Relative comfort	Reasonable comfort for wearer	Can be uncomfortable if used for long durations	Reasonable comfort for wearer
Decontamination requirement	Single use: no decontamination required	Single-use type: no decontamination requiredRe-usable type: must consider decontamination	Re-usable: must consider decontamination
Power requirement	No power required	No power required	Rechargeable battery pack required
Duration of use	Can keep same mask on for duration of the specified activity. Should be changed:– after each use; – if mask is damaged; or – if obviously contaminated with respiratory secretions or other body fluids	Can keep same respirator in use for the duration of the specified activity. Should be changed:– after each use; – if breathing becomes difficult; – if respirator is damaged; or – if obviously contaminated with respiratory secretions or other body fluids	Useable for as long as battery has sufficient power

Surgical face mask

Surgical face masks provide a barrier to splashes and droplets impacting on the wearer's nose, mouth and respiratory tract. They do not provide protection against airborne (aerosol) particles and are not classed as RPE. Whilst some surgical masks claim to have particulate filtration properties, they do not have the filtering efficiencies required for adequate respiratory protection. Moreover, most are not designed to fit closely to the wearer's face, and the poor fit means that aerosols can be inhaled having passed through the gap between the mask and the wearer's face, escaping any filtration. Although not classified as RPE, surgical face masks used for protection against infection must be fluid repellent, compliant with the Medical Devices Directive (MDD 93/42/EEC), and be ‘CE’ marked. Some surgical masks have integral eye protection.

Surgical masks should be worn for the duration of the relevant exposure, task or procedure. They should be changed if they become damaged or contaminated with respiratory secretions, only worn once, and discarded as healthcare waste following use.

Respirator

A respirator is used by an individual to provide respiratory protection. In the healthcare setting, this most commonly relates to the filtering half face mask. The European standard for filtering face masks [EN 149 (currently 2009)] lists three classes of filtering face piece (FFP): FFP1, FFP2 (approximately equivalent to N95) and FFP3. These are classified by inward leakage in laboratory tests and simulated real-life use. Inward leakage can result from penetration through the material matrix of the face piece or through any gap between the face piece and the wearer's face (see Appendix 1 ‘fit testing’). FFP3 offers the highest level of protection. Although most of the evidence base supporting the use of FFP respirators in the prevention of airborne transmission of infection is based upon N95/FFP2 devices, FFP3 is the only FFP class acceptable to HSE for use against infectious aerosols in health care in the UK (Appendix 3). In the USA, N95 (approximately equivalent to FFP2) is acceptable, as is the case in a number of other countries.

FFP respirators are available with or without an exhalation valve. Valved FFPs, although slightly more expensive, are more comfortable to wear than non-valved FFPs as the valve reduces overall breathing resistance, and heat and humidity build up in the face piece.

FFP3 respirators should be changed after each use, if breathing becomes difficult, if it is damaged, or if it becomes obviously contaminated with respiratory secretions or other body fluids. Single-use respirators should be worn once and disposed of as healthcare waste. Re-usable devices will require appropriate decontamination. The manufacturer of the respirator should provide clear instructions on the method of decontamination to be used between uses.

Eye protection

An element of facial protection that is often forgotten, eye protection provides a barrier to droplets and splashes impacting on the wearer's conjunctivae. The most commonly available items are safety spectacles, full-face visors or an integral transparent panel on the top of a surgical face mask. Eye protection should be used when there is a risk of contamination of the eyes from splashing [e.g. by secretions (including respiratory secretions), blood, body fluids or excretions]. Eye protection should always be worn by all those present in the room during potentially infectious AGPs. Disposable, single-use eye protection is recommended; however, if this is re-usable, appropriate decontamination between uses is required.

Selecting and wearing respiratory and facial protection

The requirement for and selection of appropriate respiratory and facial protection is determined by a number of factors that involve a risk-assessment-based approach considering:

the task or procedure to be undertaken;

the suspected or known infectious status of the patient; and

the presenting symptoms of the patient.

These factors are represented diagrammatically in the flow diagram in Figure 1 . This, used in conjunction with Table I, may be helpful in guiding HCWs in assessing the need for, and selection of, appropriate respiratory and facial protection. Worked examples are provided in Appendix 2.

It should be noted that Table I also provides information on the availability of immunization for the range of pathogens considered. Where such an option is available, or where immunity arising from prior infection can be established reliably, this is a powerful tool in managing the susceptibility of HCWs and a potentially important component of the hierarchy of controls. However, the degree of protection offered by immunization against different agents is variable, and the durability of protection may wane over time. In this context, the need for use of PPE still exists irrespective of immune status as it provides the last line of protection to manage any residual risk that has not been mitigated by other control measures (Appendix 3).

In summary, it should be emphasized from the foregoing that in the majority of situations where respiratory and facial protection is required, a surgical mask will be adequate. For a very small number of pathogens truly transmissible via the airborne route, or where AGPs involving infectious body fluids are being undertaken, a respirator will be required. The requirement for eye protection will largely be determined by the risk of splashing/spraying of blood and/or body fluids to the eyes/face.

With specific reference to tuberculosis, it should be noted that this guidance is essentially in agreement with the recommendations of the National Institute for Clinical Excellence and the British Thoracic Society. However, it is the authors' opinion that with the widespread availability of rapid susceptibility testing, increasingly by molecular methods, appropriate respiratory protection should be employed until multi-drug-resistant/extensively-drug-resistant disease has been excluded, rather than relying upon risk assessment (unless an AGP is being performed, in which case respiratory protection is required regardless of antimicrobial sensitivity). This is increasingly relevant in light of concerns over the rising prevalence of antibiotic-resistant tuberculosis.

The appropriate selection and use of all PPE, including respiratory and facial protection, must be underpinned by staff education and training.

A summary of current UK legislation pertaining to respiratory and facial protection is provided in Appendix 3.

Dos and don'ts of respiratory and facial protection

Do

Ensure the eye protection, surgical face mask or FFP respirator is worn correctly, completely covering the eyes, nose and mouth and secured on to the face according to the manufacturer's instructions.

Ensure the FFP respirator is ‘fit tested’ as it will be worn in practice (i.e. with eye protection if required) (see Appendix 1).

Ensure the FFP respirator is ‘fit checked’. This should be undertaken every time a respirator is worn (see Appendix 1).

Change the surgical face mask or FFP respirator if it becomes moist, wet or damaged in any way.

Ensure that the eye protection, surgical face mask or FFP respirator is removed at the end of a clinical procedure or task in the correct order to minimize the risk of self-contamination (see Appendix 1).

Dispose of single-use eye protection, surgical face mask or FFP respirator immediately after removal and in accordance with local policy.

Perform hand hygiene after removing PPE.

Don't

Pull surgical face mask or respirator down to hang around the neck.

Re-use eye protection, surgical face masks or RPE that are designated for single use.

Assume corrective spectacles will protect the eyes.

Fiddle with eye protection, surgical face mask or respirator while in position on the face.

Continue to wear eye protection if it is visibly soiled and/or vision is impaired.

Appendix 1 gives instructions regarding how to don and remove respiratory and facial protection.

Future research and evidence gaps

A survey of current UK infection prevention and control policies should be undertaken to establish the degree to which this guidance on the use of respiratory and facial protection differs from what is currently performed, and if possible to establish the source of any variations.

The uptake of use of facial and respiratory protection in areas where it is recommended, and also where it is not, should be established. This should focus on looking at areas of highest potential usage (e.g. accident and emergency departments).

Factors that influence the degree of compliance with recommendations for the use of respiratory and facial protection in comparison with other types of PPE should be examined.

It should be established which procedures are truly aerosol generating and which are not. The outputs of such research have direct practical implications for assessing the requirement for RPE.

Development of transparent respiratory protection that does not obscure the face is required to reduce patient anxiety and aid communication between HCWs and patients (e.g. in paediatric settings).

Conflict of interest statement

J.S. Nguyen-Van-Tam wishes to declare the following potential conflicts. In December 2008, he was paid for attending a GlaxoSmithKline Plc (GSK) Advisory Board to give scientific advice on the development and commercialization of an antiviral respirator. His unit currently receives research funding from GSK in areas unrelated to facial and respiratory protection.

Funding source

This work was supported by the Healthcare Infection Society.