89 room, or in a separate building, thereby minimising the number of workers at
risk.
9.1.4 Engineering Controls - Ventilation
Processes capable of producing exposures to hazardous substances only, are commonly controlled by the provision of mechanical air handling methods, of
either one of the two types below or a combination of both.
Local Exhaust Ventilation LEV
Local Exhaust Ventilation LEV - application of mechanical air handling techniques whereby potential airborne contaminants are captured near to the
source of emission, extracted, and discharged to either a safe location or subjected to some form of „air cleaning‟ technique. It is particularly valuable for
situations that involve a point source release of toxic contaminants.
General Dilution Ventilation
Dilution Ventilation - this is widely used throughout industry for the ventilation of control rooms, photographic laboratories, office spaces, mess-rooms and
printing rooms. It is not normally suitable for the control of dust, mist of fume or for substances of moderate to high toxicity, or in situations where the rate
of generation of contamination is non-uniform or high. Heating, Ventilation and Air Conditioning HVAC can also be used in a variety
of ways to control hazards associated with the thermal environment.
9.1.5 Administrative Controls
Administrative controls relate to how the interaction between personnel and the processoperation are organised. Great care is needed to ensure that
procedures, once adopted, are observed; particularly in the longer term, as shortcuts and non-
observance can become „custom and practice‟ over time, and once established can be difficult to overcome.
90 Sometimes the hazardous operation can be conducted during the evening or
night shift when fewer workers are around to be exposed. Job rotation is another method
of „protecting‟ personnel, through controlling work patterns. The worker can often influence the extent to which they are exposed to
airborne contaminants, e.g. for welding, via stance andor working upwind of the weld.
Housekeeping
Good housekeeping is particularly important in processes and laboratories where hazardous materials may be handled. Clear labelling, with relevant
health and safety advice, careful and appropriate storage and good work techniques all need to be addressed.
Handling of powders is a potentially hazardous operation and good housekeeping can help to minimise airborne contamination from spilled
materials, waste off-cuts etc. A cluttered or untidy workplace may also impede or prevent access to
essential system controls, such as LEV onoff switches, which could discourage their proper use. It can also make it difficult for workers to position
themselves correctly in relation to the task, thereby potentially risking greater exposures, and maybe even leading to problems associated with poor
ergonomics. Proper preventative maintenance schedules and regular inspectionleak
detection of process plant; plus frequent maintenance, examination and testing of engineering controls, such as LEV facilities, coupled with rapid
corrective actions where necessary, are essential if effective control is to be achieved and kept.
Personal factors are essential parts of all control strategies and are associated with the „management‟ aspects from both the perspective of how
the employer manages his employees, and how the employees „manage‟
themselves.
91
9.1.6 Information, Instruction and Training