Health is defined as the state of complete well being of a person. it does not only mean the absence of diseases or illness but also a clear state of optimum physical and mental well being. Occupational health which is a branch of human medicine deals with protection and promotion of the health of all persons at work including employees and employers. And its aims at

* Promoting and maintaining the well being (health) of the workers and employers.

* Preventing occupational (work-related) diseases and injuries at the work place

* Protecting every individual at the work place against hazards.

* Planning and maintaining the work place

* Adapting the work to man and man to work. This shows that the workers health and the working environment are closely related.

The identification and assessment of risk and hazards is only possible if one knows what hazards are and how to identify them correctly in the workplace. Hazards are objects or conditions and situations that have the potentials cause harm to the health of a person (worker and employer). Hazards are inherent in every job or work and they can be categorized into five groups thus;

1. Physical Hazards - Some of these hazards are easily felt before damage is done to the worker and they include- noise, vibrations, heat, cold, ionizing radiation, pressure and ultraviolet light.

2. Chemical Hazards - These are mostly in the form of fumes, gases, vapor, mist, dust, liquids and solids. They have three portals of entry into the body through either inhalation, ingestion, and through the skin.

3. Biological Hazards - These are in form of vectors and pathogenic biological agents. An infection known as Nasocomial infections are common features of hospital and health workers. These vectors are mostly insects and the pathogenic agents are viruses, bacterial, fungi and parasites e.t.c

4. Ergonomically Hazards - These hazards arise as a result of man-machine interactions. The predisposing factors here are poor equipment design, manual handling and inexperience at handling such equipment.

5. Psychosocial Hazards - These occur as a result of lack of job security and satisfaction; work overload and stress.

 The effects of hazards on a worker among other things are a function of the following:

* Magnitude or intensity of the dose of the hazardous agent or toxin in the worker

* The duration of exposure to the hazard or toxin and

* The frequency of exposure to the toxic substance or agent.

Having known what hazards are in the workplace and how to identify them and assess their harmful effects, we can now grade their effects in a hazard rating profile thus:

   . Slight injury and illness

   . Minor injury and illness

   . Major injury and illness

   . Permanent total disability (small exposed population)

   . Multiple disabilities (large exposed population).

 In doing this we base our judgments on the severity of the possible ill-health effect from over exposure to the agent and the chance of over exposure to the isolated agent to give an exposure rating:

A. Very Low - Exposure are negligible

B. Low - Exposures are controlled and may likely remain so in accordance with screening and performance criteria.

C. Medium - Exposures controlled to meet screening and performance criteria but cannot be assured or guaranteed.

D. High - Exposures are not adequately controlled to meet screening and performance criteria and as a result they continually exceed occupational exposure limits

E. Very High - Exposures are excessive and will almost certainly result in health damage to the worker so exposed to.

Control of hazards which is the third phase in health risk assessment or management scheme deals with the institution of measures aimed at preventing, eliminating or reducing hazards and risks or their consequences. Controls are best affected at the source of production of the hazards. it could also be directed along the transmission path and at the workers. In whatever ways control measures are put in place, their aim basically is to ensure that an exposure to a hazard is reduced to a level as low as reasonably practicable all control measures are systematized in a hierarchical order or profile for effective management. The hierarchy of controls deals with:

1. Elimination of hazard.

2. Substitution (proffering alternatives) e.g. replacing with a less hazardous substance, use a wet method instead of a dry one, introduces a non-dusting powder for  one that is friable.

3. Engineering (plant and equipment)- designing or redesigning of equipment in order to reduce their hazard producing tendencies

4. Procedural - to ensure good supervision, work methods, house-keeping, personal hygiene and to provide up-to-date information, health education, instruction and training services to better the lot of workers.

5. Personal Protective Equipment - These protective safety devices are put in place and ensure that they are used when this control measures enumerated above are not practicable.

Generally, when risks are unacceptable those control measures that could be instituted or implemented immediately should be addressed first, for example, eliminate by stopping the activity or introduce appropriate personal equipment while substitute’s alternatives measures or engineering solutions are investigated and planned and subsequently put in place when necessary. Additional control measures include routine exposure monitoring, health surveillance and good record keeping. Health surveillance becomes pertinent when risk to health in workplace cannot be excluded; it ensures that workers health is regularly monitored in order to check their fitness at any given time. Keeping records on individual's exposure to hazards and regular medical check-ups are vital to ensuring good health surveillance.

Control measures will only remain effective if they are properly and regularly maintain through regular inspections, examinations, tests and appraisals to ascertain their effectiveness.