Respiratory protective devices and surgical masks for situations involving infection risks
The difference between respiratory protective devices (RPD) and surgical masks
A RPD serves to protect the wearer from inhaling anything harmful, e.g. smoke, aerosols, fibres, bacteria or virus. Rules and standards for design are governed by the Council Directive of 21 December 1989 on the approximation of the laws of the Member States relating to personal protective equipment (89/686/EEC).
Face (surgical) masks are meant to prevent the spread of droplets from the wearer. Rules and standards for design are governed by the EU Council Directive on the approximation of the laws of the Member States relating to Medical Devices (93/42/EEC).
Respiratory protective devices
There are various types of RPD. These are described at greater length in the book Din personliga skyddsutrustning, published by the Work Environment Authority (available only in Swedish). European standards useful for this area are EN 133 Respiratory protective devices – Classification and EN 134 Respiratory protective devices – Nomenclature of components.
Filtering devices: The ambient air passes through a filter. A filtering device can take the form of a full face mask or a half mask with replaceable filters or masks of filter material (filtering half mask). The last mentioned are sometimes also known as filtering facepieces (FF). Masks of filter material are sometimes fitted with an exhalation valve.
A visor or hood can be power assisted and serve as filtering device with ambient air passing through a filter.
Breathing apparatus: The wearer is supplied with air or oxygen from an independent source, through a hose or from a portable pressure vessel.
Filter
Swedish and European standard (SS-EN) requires the filter in a respirator to meet filter performance requirements for both solid particles (NaCl) and liquid particles (paraffin oil). The filters are classified according to their efficiency in separating such particles ranging in size from 0.1 to 1.0 μm. (Gas filters are not dealt with here.)
P indicates that the filter separates particles. A figure indicates the separating efficiency, which is highest in class 3 filters. P3 separates 99.95% and P2 94.0% of both solid particles and oil mist.
(An American standard with the designation N indicates that they have not been tested for liquid particles. N95 is presumed to separate 95% of solid particles.)
Fit
The separating efficiency of the filter is only a part of the face mask’s protection factor. The tightness of fit against the face is a very important factor. The RPD is individually fitted and tested for leakage (holding a hand over the filter and breathing in if it is a mask or facepiece, or breathing out vigorously if it is a filtering mask with no valve). If the mask is not a perfect fit, owing to beard growth or for some other reason, a power assisted device will have to be used instead.
Handling, practice
It is important to don the RPD in such a way that it fits closely. When removing it, remember that both mask and gloves (if any) may be contaminated. Hand hygiene matters! Careful instructions are needed concerning the handling of RPD, and the donning and removal of them needs to be practised. The filters to full face masks and half masks are replaceable and are discarded after use. These masks can be reused after cleaning and disinfection. Contaminated masks of filter material are discarded in their entirety. The risk assessment, that has to be done by the empolyer in all cases, will prove whether used filters and masks of filter material have to be treated as infectious waste.
Choice of protection level
A RPD is needed to protect the wearer from airborne infection. They can afford different degrees of protection, and care must therefore be taken to choose the right RPD for the right occasion. A RPD with a P3 filter, e.g. mask of filter material FFP3, can be used for protection against airborne viral or tubercular infection. FFP2 is used where requirements are less exacting.
The eyes often need to be protected as well, in which case a full face mask or a power assisted hood or visor affords good protection. A half mask or mask of filter material needs to be supplemented with safety goggles or a visor.
A surgical mask is not sufficient to protect the wearer from airborne infection but can to some extent reduce exposure to droplet infection. It is mainly intended to trap particles which can spread from the user’s nose and mouth and is, for example, worn by medical personnel to avoid infecting patients with surgical incisions or burns. It can also be used to protect others against droplet infection from a patient sneezing or coughing, e.g. a patient suffering from SARS. In cases of this kind a RPD is less suitable, especially a mask with an exhalation valve, because in that case the exhaled air will not be filtered.
Provisions from the Swedish Work Environment Authority on RPD
There are several Provisions containing stipulations on personal protective equipment including respiratory protective devise, e.g. AFS 2005:1 Microbiological Work Environment Risks – Infection, Toxigenic Effect, Hypersensitivity. Special Provisions on Use of Personal Protective Equipment are contained in AFS 2001:3. See also the book Din personliga skyddsutrustning.
Suppliers
Suppliers of respiratory protective devices are obliged to furnish them with special CE marking and with Swedish instructions for use. Suppliers often have further valuable information to offer concerning these products.
