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system provides respiratory protection in toxic, corrosive, dusty and oxygen-deficient
atmospheres.

There are three main types of self-contained breathing apparatus, classified mainly on the
basis of duration and use:
• Escape sets that have a limited supply of compressed AIR lasting about 10 minutes.
• General breathing apparatus with a larger cylinder of compressed air lasting up to 45-
60 minutes at normal working rates.
• Oxygen sets used for medical purposes (and perhaps in certain specialised applications).

Selection, Use and Maintenance

• The selection of appropriate respiratory protection is based on three main criteria:

• Type of hazard: whether the hazard is dust, corrosive or toxic substances, or oxygen
deficiency, etc.
• Contaminant concentration: the extent to which filters can reduce the concentration to a
safe level, or complete protection is required.
• Wearer acceptability: the extent to which users are able to use the system in comfort whilst
undertaking the work. To give full protection, respiratory protection systems must be worn
during all of the time the hazard is encountered. Poor wearer acceptability may result from
misting visors, unbalanced strain upon the head and neck muscles, a feeling of head
discomfort (possible headaches) from headbands, difficulty with breathing and
conversation, overheating of the area around and covered by the face-piece, excessive
sweating and possible dermatitic response, to name but a few. There is a high probability
that the equipment will be removed during use by a wearer to gain some relief from such
discomfort.

All PPE must be maintained in efficient working order by defined maintenance at a specified
frequency or, where appropriate, by a programme of regular replacement. It must also be
stored safely when not in use.
Other Personal Protective Equipment (PPE) for Chemicals

While PPE should only be relied upon as a last line of defence, its use is often essential when
working with chemicals and required to supplement higher level control measures.

PPE when working with chemicals includes but may not be limited to overalls, aprons, footwear,
gloves, chemical resistant glasses, face shields and respirators.

Appropriate PPE must be selected and used specifically for the hazardous chemical(s) in question,
be a suitable size and fit, maintained appropriately and worn and used correctly by workers.

ENSIGN| Unit IG2 – Element 7 – Chemical and Biological 41
Agents