Selecting the types of respiratory protection equipment to be used
Adequate against the hazard
Adequate
against the hazard means two things:
- That it is the correct equipment for removing or reducing the exposure to the hazard which is being targeted, and
- That it reduces exposure to the hazard to a level which will not harm the wearer’s health or safety.
The
selection of respiratory protective equipment should be carried out by a
competent person with knowledge of the level of each contaminant in the
external air and the safe level for breathing (usually given on the Safety Data
Sheet). The information is used to calculate the APF required. The APF then
dictates the type and model of respiratory protection to be used.
The
HRA may have required the industrial hygienist to measure or estimate the
concentrations of hazardous substances in the air. The hygienist can then look
up the WEL for these substances. By dividing the actual concentration by the
WEL for each, the hygienist can calculate the APF required and thus select the
type of respiratory protection which does the job.
Respiratory
protection suppliers publish the APF figures for each of their models. In
general, disposable facemask respirators and cartridge half masks have an APF
of around 20, cartridge full face masks around 40, airline breathing apparatus
around 200, and self-contained breathing apparatus around 2000.
In
the U.S., the Occupational Safety and Health Administration has published
default APFs for the major types of respirators which can be referred to via
the OSHA Standard 29 CFR 1910.134 for Assigned Protection Factors.
The
physical nature of the contaminant in the air must also be considered. Dusts,
aerosols, vapours and gases required different types of filter to be removed.
Filtering
respirators must not be used where oxygen deficiency is a problem. Only
breathing apparatus can deliver air with the correct oxygen level. Where RPE is
required in a confined space during hot work activities or activities that
could potentially effect the oxygen levels in the confined space (such as when
disturbing gases in sludges at the bottom of tanks, welding, needle-gunning,
accessing chain lockers on Vessels/FPSOs, etc.), either fresh air hoses or
constant-flow breathing apparatus are to be used to protect users from airborne
particles, fumes and potential increases in carbon dioxide levels due to the
work task.
It is important that the air being delivered meet the relevant quality standards. This may require a qualified expert, such as an industrial hygienist, to test the air or review air quality certifications before use
Suited against the task
The task being carried out under respiratory protection may have elements which affect the selection. For example, airline or self-contained breathing apparatus may not allow the wearer to go into tight spaces.
If other types of PPE, such as head, hearing or eye protection, need to be worn, they may interfere with certain types of
respiratory protection, and this will
also affect the selection decision. Most manufacturers offer combination (or
integrated) PPE, which combines head, hearing, eye and respiratory protection.
Full
face masks generally limit visibility, both because they give a limited view at
the edges, and because the plastic screen loses some transparency. So, if the
task requires visual accuracy, this should be considered.
Suitability factors
Suited to the Work Environment
If the work
environment is challenging, for example if it is hot, wet, slippery or
chemically contaminated, this should be considered. If the work is at height or
depth, access issues may limit the decision, particularly if ladders have to be
negotiated.
Where RPE is required in a confined space during hot work activities, such as welding, the use of either Fresh Air Hose or Constant Flow breathing apparatus should be used to provide adequate protection to the user from air borne particles, fumes and potential increasing carbon dioxide levels due to the hot work task
Suited to the Wearer
Working with respiratory protection puts an extra load on the wearer in terms of ease of breathing, and also weight, heat and access problems. Fitness to Work testing for breathing apparatus users will determine
whether the user has the fitness required to handle the extra load. Facemasks require a good seal between the face and the edge of the mask in order to stop leakage round the mask. This can be difficult to achieve, and several types of mask may need to be tried to find the one which fits best. The material of the mask, particularly those with a rubber seal, can make a big difference. Facial hair, particularly beards and sideburns, can also interfere with the seal. If the user has facial hair and is prepared to shave it off, that is the best solution. If not, a head-enclosing (loose-fitting) mask may be necessary
