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Protection of workers against occupational hazards can be achieved by the following order of
priority :

1.   Elimination
2.   Engineering Control
3.   Administrative Control
4.   Personal Protective Equipment (PPE)


The presence of hazards that can cause physical and health effect to workers can be eliminated by
 Substituting hazardous tool
 Machinery
 Chemical substances and the process that are less hazardous


If elimination is not possible the hazard should be guarded or isolated from the worker. This
involves imposing a barrier (physical barrier or distance) between the hazard and the worker. Local
and General Ventilation is used to dilute or divert toxic contaminants from the workers.

Safe operating procedures (SOP), Shift work and training of workers can reduce the risk to the
workers handling chemicals.


If it is not possible to reduce chemical hazards to an acceptable level, by either elimination or
guarding/isolation, the worker should be given certain protective equipment to prevent contact of
the hazards with the body. This equipment forms a barrier between the toxic and the route of entry.
Failure of equipment means immediate exposure to the hazard. Thus, personal protective
equipment should not be regarded as a primary means to control hazards but rather as a
supplement to other types of control measure.

Injury will occur if hazards come into contact with our body, the degree of injury are depends on the
magnititute of hazards and susceptibility of person.

                                   Respirator - designed to absorb the contaminant that come
The principle of using of PPE       into contact by inhalation
is to prevent contact between      Protective clothing, gloves, apron, goggles and shoes –
the hazard and the internal or      design to prevent absorption of chemical splash to the skin
external part of our body .        Safety helmet-to prevent from the sharp object falling on the
The effectiveness and efficiency of protection depends on proper use, maintenance and
replacement of the PPE. If the PPE not used properly it can be more dangerous than not using as
the worker would think that he is protected but in actual practice he is not protected.

Factor to consider in the selection of PPE

PPE should be carefully selected. The following criteria should be met when choosing PPE

 Give adequate protection against the specific hazard i. e right type and model
 Fit , minimum weight cause minimum discomfort and , if with attachment , it should be easily
  fitted and removed.
 Not restrict movement or sensory perception essential to the job
 Be easily worn and the eight to be supported by body
 Be durable and harmonious to the wear1`s culture and religion
 Not introduce additional hazards
 Be made to acceptable standards
 Be maintenance fee if possible, if maintenance is required , should be easily maintained
 Be replaced when necessary


Used of respirators will prevent the entry of chemicals into the body by inhalation It is frequently
used in industry where other forms of control are not practicable
Type of respiratory protection :
Are basically design to give protection against one or more of the following .

 Contaminants in particulate forms
 Contaminants in gaseous forms
 Deficiency of oxygen


               respirator                                                         Air-supply

filter                          cartridges                             Remote source             Portable type
                                                                       (Air line)                (SCBA)

With Full face mask or Half face mask
Powered - air is drawn through by a fan
Non powered – air is drawn through by wearer inhalation

 Air purifying respirators

  particulate filters- which
   filter out mechanically          Particulate filter come in various classes depending on their
   or thermally generated           filtering efficiency.

  cartridges- which absorb         Gas filters are available for specific gases (e.g organic vapours,
   certain gases , fumes,           hydrogen, cyanide)
   mist and vapours

Supplied air respirators (SARS)

  Main type of SARS
   Air Hose Respirator
                                     The air is supplied is not pressurized. It can be supplied by
                                      use of a fan , compressed air source or wearer inhalation. .
   Air line Respirator
                                     The air supplied is pressurized and comes from a
                                      compressor or gas cylinder via an air line . Pressure is
                                      reduced prior to entering the respirator.
     Self contained breathing
      apparatus(SCBA)                The air is supplied from cylinders strapped to the wearer`s

Suppliers air respirators can have a negative pressure inside the face piece or a positive pressure.
The positive types give a significantly higher level of protection . Continuous flow types are also
available for use with hoods.

Protection factors

This is a measure of the level of protection given by a respirator is defined as the ratio between
the concentration of contaminant outside the respirator and the concentration inside the
respirator(i. e the air breathed)
Protection factor = ambient air concentration
                    Concentration inhaled inside respirator

For air purifying respirator it depends on the type of face mask and the efficiency of the filter. A full
mask provide a higher level of protection than a half mask.

For supplied air respirator it depends on pressure inside the mask(as well as the type of mask) .

The protection factor is a major consideration when selecting a respirator.

Selection of respirators; depends on:-

 The contaminant
 Task
 Operator

The contaminant

i.      The nature ,toxicity, physical form and concentration the contaminant, whether :
        or combination of both

ii.     whether failure of the device can result in a situation which is immediately dangerous to life
        and health.
iii.    The need to wear other personal protective equipment eg. Eye or skin protection to protect
        against irritants.
iv.     The adequacy of warning given by the contaminant
v.      The possibility of the contaminated atmosphere being flammable.


i.      whether the device is for regular use for emergency or rescue purposes.
ii.     The probable length of time during which the wearer will be in the contaminated
iii.    The expected level of activity and mobility required of the wearer.
iv.     The access to and nature of the working environment and its location with respect to a
        source of air suitable for breathing.
v.      Vision and communication requirements.
vi.     Maintenance requirement.

Operator factor

 Basic physiology
 Facial fit
 User acceptance

Fit testing is an important part of the selection process, particularly when the respirator design
relies on a good seal. A range of respirators may need to be tried to fit individuals with different
facial characteristics. Facial air can also reduce the effectiveness of seal significantly.

Recognised test methods are available for initial fit testing. These are to design to detect or
measure the amount of leakage around the seal of the respirator. Fit testing must be carried out
when first issuing a respirator to a worker.

Crude test (such as covering the openings and taking a vigorous breath) can be used in the field to
check fit.

Maintenance and storage

All respirator (other than disposable types) need cleaning , maintenance and storage.

Inhalation and exhalation valves need checking and replacement as do straps. Seals need to be
disinfected , cleaned and check for damage. Respirators and filters need to be stored in a clean,
air tight container.

Employees required to wear respirator must receive training on :-
 The hazard to which they are exposed
 The function of respiratory protection
 The correct use of the respirator include fit testing
 Storage and maintenance of the respirator

This include safety glasses face shields and goggles to protect against physical injury by particles
or injury from corrosive liquids , vapours and gasses. Goggles provide a seal against the face and
give better protection against vapours and gasses than safety glasses. Full face masks used with
some respirators also protects the eyes and face.
Tinted lense can be used to shield against ultraviolet and infrared radiation.


This can be includes ear plugs, ear muffs and helmets.

Gloves, boots, coverall, plastic aprons are among the range of protecting clothing available to
protect employees against exposure to chemicals. Care must be taken to select the correct
clothing for the job. Information in the manufactures MSDS should be used to make the selection.
Number of factors need to be considered when selecting protective clothing
i.    the design of the article needs to be appropriate for the task. Wrist length gloves, for
      instance, will not protect a worker if they must immerse their arms beyond the wrist.
      Similarly ordinary safety glasses offer poor protection against gasses or vapours. Sealed
      goggles or a full face masks are required.

ii.     The clothing must be made of appropriate material. Cotton coverall are not appropriate
        where impervious clothing is required.

        The solvents are another god example. They attack many of the polymers from which
        gloves are made. Gloves need to be specifically selected to the solvent that being used.

iii.    workload and working conditions must be considered. Clothing such as impervious or
        chemical resistant coveralls may provide good protection but may cause heat stress in hot
        humid conditions.

iv.     Maintenance and cleaning is important . if this is difficult or dangerous,disposable clothing
        can be considered.

Manufacture provide a selection of clothing made out of polymers such as PVC, rubber neoprene,
PVA and viton. Leather, cotton and synthetic fibres are also used for certain type of clothing.
Protective clothing for use with acids, alkali, solvents, pesticides, oils as well as radiation, heat and
cold are available .

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