Selection of Respiratory Protective Equipment (RPE)
Respiratory protective equipment selected must provides adequate protection against
the hazard, is comfortable to the wearer and does not interfere with the work. However, there is often a
trade-off between protection and comfort.
The following are examples of each type of respiratory protection. They also give typical Assigned Protection Factors (APF), and common applications. Only types and models approved by local authority (e.g. NIOSH in the USA, In Europe have CE markings and appropriate EN certifications) should be used.
Respirators
can be non-powered (relying on the wearer’s breathing to draw the air through
the filter) or powered (using a small pump or fan to draw the air through the filter).
Powered respirators put less load on the lungs, and have the additional advantage
(along with breathing apparatus) of maintaining a positive pressure inside the
facemask, so any leakage will be outwards rather than inwards.
Some
facepiece respirators have an exhalation valve built in. This allows inhaled
air to pass through the filtering fabric or cartridge of the respirator, but
exhaled air passes through the valve. This helps to keep the facemask tight
against the face.
Understanding How to Select the Correct APF Value
All
respiratory protective equipment is assigned an Assigned Protection Factor (APF)
that allows a specialist to select the correct type of RPE and Filter/ Cartridge
to protect the user from the hazards associated with the job based on the
Workplace Exposure Limit (WEL) of the hazardous substance the user is working
with.
For
instance if a worker was working with softwood (particulates) where the concentration
in the workplace from the task is 55 mg/m3, and this product has a WEL of 5
mg/m3 over an 8hr Time-Weighted Average (TWA). The calculation to work out the
required APF Level of respiratory protection is completed as follows:
55
mg/m3
5 mg/m3
= 11 x WEL (5 mg/m3)
This means you would need a facemask with an APF
of at least 11, which would mean using a particulate filter FFP3 facemask as it
has an APF of 20 rather than a FFP2,
which has an APF of 10.
Types of Respiratory Protective Equipment (RPE)
Disposable Facemask Respirators
Disposable
facemask respirators are simple devices which cover the mouth and nose. The breathing
air passes through the material on the mask, which is capable of removing the contaminant
from the breathing air by filtering or absorbing it.
These usually have a bridge which can be pinched to get a better fit over the
nose, and may have a valve to allow exhaled are to escape more efficiently. Each
model and type of respirator is designed to protect from one hazard so, for
example, a nuisance dust mask should not be used for organic vapours.
Their most common use is for protecting against solid particles such as
nuisance dusts, for example when needle-gunning or emptying sacks into a
hopper. They have an APF of 4-20 (FFP1=4,
FFP2=10, FFP3=20). This means that for an APF of 4 the facemask will provide
the user protection up to four times the WEL
Figure 1 – Examples of Disposable Facemask Respirators
Cartridge/ Filter Half Mask Respirators
Cartridge half mask respirators consist of a rubber or
polymer housing with one or two cartridges fitted into the housing. The
breathing air passes through the cartridges, which remove the contaminant from
the breathing air by filtering or absorbing it.
The
housing is more flexible than for disposable respirators, so a better fit and
face seal can be obtained, however they are heavier. They are used for
protecting against solid or liquid particles such as nuisance dusts and oil
fumes, and for gases and vapours such as paint solvents or ammonia.
They have an Assigned Protection Factor of
4-20 (P1=4, P2=10, P3=20) for particulates, and 10 for gases and vapours
Figure 2 – Examples of
cartridge/filter Half Mask Respirators
Cartridge Full Face Mask Respirators
Full face mask respirators work in the
same way as half mask respirators, with a rubber or polymer housing fitted with
one or two cartridges, which remove the contaminant from the breathing air.
However, they also incorporate an eye screen in the housing.
As well as protecting the eyes, this
gives a better face seal, but it does make them heavier, and restricts vision.
They also need more maintenance
Figure 3– Examples of Cartridge Full Face Mask Respirators
Self -Contained Breathing Apparatus (SCBA)
Self-contained breathing apparatus feeds breathing quality air from a cylinder carried on the back via a demand valve to the facemask. This allows better access into vessels and awkward spaces than airline breathing apparatus. Their main uses are for protecting against solid or liquid particles, gases and vapours. They are used in oxygen depleted atmospheres, such as vessel entry. They have an Assigned Protection Factor of 2,000 with a full face mask.
Figure 5 – Example of a Self-Contained Breathing Apparatus
